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Abstract

Natural fiber composites (NFCs) are an evolving area in polymer sciences. Fibers extracted from natural sources hold a wide set of advantages such as negligible cost, significant mechanical characteristics, low density, high strength-to-weight ratio, environmental friendliness, recyclability, etc. Luffa cylindrica, also termed luffa gourd or luffa sponge, is a natural fiber that has a solid potential to replace synthetic fibers in composite materials in diverse applications like vibration isolation, sound absorption, packaging, etc. Recently, many researches have involved luffa fibers as a reinforcement in the development of NFC, aiming to investigate their performance in selected matrices as well as the behavior of the end NFC. This paper presents a review on recent developments in luffa natural fiber composites. Physical, morphological, mechanical, thermal, electrical, and acoustic properties of luffa NFCs are investigated, categorized, and compared, taking into consideration selected matrices as well as the size, volume fraction, and treatments of fibers. Although luffa natural fiber composites have revealed promising properties, the addition of these natural fibers increases water absorption. Moreover, chemical treatments with different agents such as sodium hydroxide (NaOH) and benzoyl can remarkably enhance the surface area of luffa fibers, remove undesirable impurities, and reduce water uptake, thereby improving their overall characteristics. Hybridization of luffa NFC with other natural or synthetic fibers, e.g., glass, carbon, ceramic, flax, jute, etc., can enhance the properties of the end composite material. However, luffa fibers have exhibited a profuse compatibility with epoxy matrix.

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... Indeed, NLF-reinforced polymer composites are well known for their weak interface due to the general hydrophobic characteristic of the polymer matrix and the hydrophilic characteristic of the fibers. This is the case for the luffa/Polyurethane composites, where the weak interfaces between the phases were reported together with the mechanical behavior effect of the fiber surface treatment [43][44][45]. ...
... However, the better result for the composite can be associated with the luffa mat configuration. As already discussed in this work, in accordance with the literature [43][44][45], this interlink between the luffa fibers acts as a good anchor for the resin. This behavior is most likely responsible for the composites enhanced behavior compared to the plain COPU resin. ...
... This causes rupture, as part of the energy will be spent in the ramifications of the luffa fibers and in the processes of detaching them from the matrix. The luffa's spongy nature and vascular system also contribute to greater energy absorption [43,44]. ...
Article
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The main objective of this work was to produce and characterize a novel ecofriendly castor oil-based polyurethane (COPU) matrix composite reinforced by Luffa cylindrica mats, luffa for short, to be used as panels, as an alternative to oriented strand board (OSB). To do so, the mechanical behavior was evaluated by tree point flexural, perpendicular o surface tensile, screw pullout, and impact tests that were carried on the novel composite along with the neat matrix. Furthermore, the physical characteristics, the thermomechanical behavior, and the functional groups of the materials were observed by water absorption and thickness swelling tests along with dilatometry and Fourier transform infrared spectroscopy (FTIR). A comparison with commercialized OSB was also performed for control. The luffa/COPU composite was prepared by hand lay-up with 48 vol% of luffa mats incorporated as the maximum allowed by the mold under the available resources for manufacturing. The luffa fibers acted as a good reinforcement for the COPU matrix, where the flexural strength and modulus of elasticity were increased by more than 23 and 10 times, respectively, and the other mechanical properties more than doubled for the composites compared to the neat COPU resin. In general, the composite presented a lower performance compared to the commercial OSB, with the impact results being the exception. The water absorption and thickness swallowing results showed an already-expected behavior for the studied materials, where the better performance was found for the hydrophobic neat resin. The FTIR revealed that there was little interaction between luffa and COPU resin, which can be translated to a weak interface between these materials. However, the mechanical behavior, together with the other results presented by the luffa/COPU composite, confirm it is more than enough to be used as civil construction panels such as OSB.
... However, there is a distinction between the hoop wall and the core which is the loose connection of fibres in the core region as well as the presence of a single fibre running along central point of the entire LFC (Figure 3d) [27]. The major composition of LCF are hemicellulose, lignin and cellulose while other inorganic chemicals such as glycosides, proteins, polypeptides and amino-acids may be found in them as well [28]. Different values have been allotted to these constituents from different sources as seen in Table 1. ...
... Some physical properties include mean density of $270mm, microfribillar angle of [28]. It must be stated that the density of LCF is much lower than that of other popular vegetable fibres which include coir at 1.25 g/cm 3 , hemp at 1.48 g/ cm 3 , cotton at 1.5 to 1.6 g/cm 3 , ramie at 1.5 g/cm 3 and sisal at 1.26 to 1.45 g/cm 3 [29]. ...
... Micrograph of (a) untreated, (b) alkali treated, (c) combined treatment, (d) acetylated treated luffa cylindrical fibres (Source: Ref.[28]). ...
Article
Luffa cylindrica fibre (also known as sponge gourd) is widely available in major parts of Asia and Africa because it is a good source of cellulose fibre. The fibre is cheap, available free in nature, possesses excellent composition and will provide a sustainable fibre reinforced cementitious composite for various applications. Studies and published articles on its use are found in other non-cement based areas but little or no review has been performed on its relevance to cement composites. This is because it is an emerging field of study with limited information on what the fibre is all about. This review gives a compendium of the limited available concluded studies on the use of luffa cylindrical fibre as reinforcement in different cement based matrices. Therefore, the major highlights reviewed included its source, physical, chemical and mechanical compositions, pre-treatment methods, drying shrinkage, compressive and flexural strengths and microstructural analysis of the cement composites. This review was able to establish the important role it played in improving some of these earlier listed properties of the cementitious materials considered. However, further studies in the future are needed to be able to establish some parameters which will aid its adoption in cement based medium such as appropriate treatment methods, optimum content, effective reinforcement form or type (dispersed type or fabric/lay up mat form) and durability studies. It is desired that through this review, interest in the use of luffa cylindrical fibre as an important cellulose fibre for reinforcement in cement based materials will be kindled.
... However, there is a distinction between the hoop wall and the core which is the loose connection of fibres in the core region as well as the presence of a single fibre running along central point of the entire LFC (Figure 3d) [27]. The major composition of LCF are hemicellulose, lignin and cellulose while other inorganic chemicals such as glycosides, proteins, polypeptides and amino-acids may be found in them as well [28]. Different values have been allotted to these constituents from different sources as seen in Table 1. ...
... Some physical properties include mean density of $270mm, microfribillar angle of [28]. It must be stated that the density of LCF is much lower than that of other popular vegetable fibres which include coir at 1.25 g/cm 3 , hemp at 1.48 g/ cm 3 , cotton at 1.5 to 1.6 g/cm 3 , ramie at 1.5 g/cm 3 and sisal at 1.26 to 1.45 g/cm 3 [29]. ...
... Micrograph of (a) untreated, (b) alkali treated, (c) combined treatment, (d) acetylated treated luffa cylindrical fibres (Source: Ref.[28]). ...
Article
Luffa cylindrica fibre (also known as sponge gourd) is widely available in major parts of Asia and Africa because it is a good source of cellulose fibre. The fibre is cheap, available free in nature, possesses excellent composition and will provide a sustainable fibre reinforced cementitious composite for various applications. Studies and published articles on its use are found in other non-cement based areas but little or no review has been performed on its relevance to cement composites. This is because it is an emerging field of study with limited information on what the fibre is all about. This review gives a compendium of the limited available concluded studies on the use of luffa cylindrical fibre as reinforcement in different cement based matrices. Therefore, the major highlights reviewed included its source, physical, chemical and mechanical compositions, pre-treatment methods, drying shrinkage, compressive and flexural strengths and microstructural analysis of the cement composites. This review was able to establish the important role it played in improving some of these earlier listed properties of the cementitious materials considered. However, further studies in the future are needed to be able to establish some parameters which will aid its adoption in cement based medium such as appropriate treatment methods, optimum content, effective reinforcement form or type (dispersed type or fabric/lay up mat form) and durability studies. It is desired that through this review, interest in the use of luffa cylindrical fibre as an important cellulose fibre for reinforcement in cement based materials will be kindled.
... The major composition of LCF are hemicellulose, lignin and cellulose while other inorganic chemicals such as glycosides, proteins, polypeptides and amino-acids may be found in them as well [28]. Different values have been allotted to these constituents from different sources as seen in Table 1. ...
... Some physical properties include mean density of $270mm, microfribillar angle of [28]. It must be stated that the density of LCF is much lower than that of other popular vegetable fibres which include coir at 1.25 g/cm 3 , hemp at 1.48 g/ cm 3 , cotton at 1.5 to 1.6 g/cm 3 , ramie at 1.5 g/cm 3 and sisal at 1.26 to 1.45 g/cm 3 [29]. ...
... Micrograph of (a) untreated, (b) alkali treated, (c) combined treatment, (d) acetylated treated luffa cylindrical fibres (Source: Ref.[28]). ...
Article
Luffa cylindrica fibre (also known as sponge gourd) is widely available in major parts of Asia and Africa because it is a good source of cellulose fibre. The fibre is cheap, available free in nature, possesses excellent composition and will provide a sustainable fibre reinforced cementitious composite for various applications. Studies and published articles on its use are found in other non-cement based areas but little or no review has been performed on its relevance to cement composites. This is because it is an emerging field of study with limited information on what the fibre is all about. This review gives a compendium of the limited available concluded studies on the use of luffa cylindrical fibre as reinforcement in different cement based matrices. Therefore, the major highlights reviewed included its source, physical, chemical and mechanical compositions, pre-treatment methods, drying shrinkage, compressive and flexural strengths and microstructural analysis of the cement composites. This review was able to establish the important role it played in improving some of these earlier listed properties of the cementitious materials considered. However, further studies in the future are needed to be able to establish some parameters which will aid its adoption in cement based medium such as appropriate treatment methods, optimum content, effective reinforcement form or type (dispersed type or fabric/lay up mat form) and durability studies. It is desired that through this review, interest in the use of luffa cylindrical fibre as an important cellulose fibre for reinforcement in cement based materials will be kindled.
... Cellulose is a linear stiff chain homopolymer composed of monosaccharides of D-glucopyranose units associated via a 1,4-glucosidic linkage [8]. LC fibers form a net-like fibrous vascular system that has incredible properties such as high porosity, excellent physical properties, non-toxicity, light-weight, high mechanical strength, slow degradation and low-cost availability [5,6,9]. Based on these factors over the past few decades the researchers have been more interested to choose LC as a reinforcement material for fabrication of composite scaffolds that could provide an excellent supporting framework and suitability for a variety of applications, including therapeutic, pharmaceutical engineering, drug delivery system, environmental engineering, tissue engineering, automobile industries, biotechnology and medical interventions [10]. ...
... The liquid retaining potential of the composite scaffolds was assessed by submerging scaffolds with a height of 5 mm and a diameter of 10 mm at room temperature in a phosphate-buffered saline (PBS) solution (pH 7.4 at 37 C) for 72 h. The weight gain of PBS immersed scaffolds was taken at regular intervals of time i.e.1,2,3,4,5,6,7,8,9,10,12,24,48 and 72 h. At regular intervals, samples of PBS solution were taken and weighed using a high-precision weighing scale after being ...
Article
Bone tissue engineering is an emerging technology that has been developed in recent years to address bone abnormalities by repairing, regenerating and replacing damaged/injured tissues. In present work, we report the fabrication and characterization of porous luffa-based composite scaffolds composed of Luffa cylindrica (sponge gourd) powder (LC)/hydroxyapatite (HA), psyllium husk (PH) and gelatin (G) in various combinations (w/v) i.e. 3% LC, 5% LC and control (C) (without luffa powder) by using freeze-drying method. The structural stability of the scaffolds was obtained after chemically crosslinking them with glutaraldehyde (GTA), which was identified via scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The hydrophilic behavior of the samples was quantified by water contact angle measurements. The average pore size of the scaffolds was observed in a range of 20-240 µm. As per the obtained data, the apparent and effective porosities were estimated as ∼57.08 ± 4.38%, ∼50.58 ± 4.09%, ∼59.45 ± 1.60% and 51.37 ± 3.36%, 47.94 ± 4.57% and 53.09 ± 5.45% for 3% LC, 5% LC and control (C) scaffolds respectively. The scaffolds were found to be noticeably stable for 50 days at 37 °C in a lysozyme solution. The liquid retention capacity of the scaffolds revealed that the luffa-based scaffolds gained lower retention capacity compared to the control (C) scaffold; indicating an increase in scaffold stiffness due to the addition of luffa. Compressive strength study demonstrated that the mechanical stability of the fabricated luffa-based scaffolds got increased significantly from ∼1.5 to ∼9.5 MPa, which is comparable to that of trabecular bone. In addition, proliferation and viability analysis of MG-63 osteoblast-like cells revealed a significant level of cellular compatibility i.e., approaching ∼64% proliferation by 6th day in vitro compared to control. Thus, the obtained results demonstrate that the fabricated novel luffa-based scaffolds exhibit good cytocompatibility, remarkable porosity and excellent mechanical strength comparable to native human bone. Therefore, we anticipate that the developed luffa-based scaffolds could be a promising potential for bone tissue engineering applications.
... The FT-IR spectra of untreated LC fiber and its treated species LCC indicated the broad absorption peaks of -OH stretching vibration at around 3350 cm − 1 , peaks of -CH asymmetric and symmetric aliphatic bending vibration at around 2915 cm − 1 and peaks of C-O-C pyranose ring skeletal vibration at around 1010 cm − 1 . One can see that both significantly decreased characteristic peak of lignocellulose material at around 1430 cm − 1 and lowered intensity of >C=O stretching vibration at around 1715 cm − 1 related to the by-product of lignin degradation, indicating the success of combined process conducted to remove the lignin or other impurities [54][55][56]. In the case of neat PCL, the stretching vibrations seen at around 2915, 1720 and 1165 cm − 1 were related to -CH, >C=O and C-O-C groups. ...
... The lightweight natural pristine LC fiber used in this study has a WCA value of 39 • ± 1. After the application of chemical treatment procedure on LC, the WCA value of LCC was determined as 13 • ± 1 most likely owing to the absence of hemicellulose and lignin ingredients or elimination of non-cellulose substances leading to the emergence of free hydrophilic hydroxyl groups, increase in amorphous cellulose content and enhancement in the surface roughness [56,63,64]. Furthermore, the incorporation of hydrophobic PCL segments with a WCA of 85 • ± 1onto the LCC main chain improved again the WCA value to 48 • ± 1, denoting the lower wettability than that of both LC and LCC, as anticipated [65]. ...
Article
In this research, a bio-based graft copolymer (LCC-g-PCL) based on the cellulose of Luffa cylindrica (LCC) main chain possessing poly(ɛ-caprolactone) (PCL) pendant groups is synthesized through a grafting from approach via ring-opening polymerization (ROP). For this purpose, LCC, extracted from luffa sponges by combined method, is utilized for ROP of ɛ-caprolactone (ɛ-CL) as a macro-initiator in the presence of stannous octoate as a catalyst. Fourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopies are utilized to structurally indicate the success of ROP, while the achieved graft copolymer is analyzed in detail by comparing with LCC and neat PCL in terms of wettability, thermal and degradation behaviors by conducting water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) and in vitro both hydrolytic and enzymatic biodegradation tests, respectively. The results of conducted tests show that the incorporation of PCL groups on LCC provide the increasing hydrophobicity. In addition, the degradation behavior of the LCC-g-PCL copolymer is found to be more pronounced under enzymatic medium rather than hydrolytic conditions. It is anticipated from the results that LCC-g-PCL can be a potential eco-friendly material particularly in bioplastic industry.
... Mota [12] studied a polymeric composite reinforced with LC fibers treated with boiled water and reported that although matrix-fibers adhesion was low, fibers reduced cracks propagation. Finally, an interesting review of developments on natural luffa fibers composites can be seen in [16]. ...
... The R-Squared values with the best fit and the iteractions performed were 0.993, 0.986 and 0.985 and 45, 34 and 52 for the LN, LW and LS samples, respectively.InFig. 4, it is possible to see all of the most significant peaks corresponding to the amorphous and crystalline phases of the samples at 2q around16 and 22 , respectively. Besides, it presents the deconvolution, Fig. 4a, with the baseline subtracted, which identifies the overlapping peaks of the amorphous and crystalline regions at 2q around 14, 16, 20, 22 and 34 , and the disappearing crystalline phases in LW and LS samples when compared to the LN one. ...
Article
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The development of new materials or the improvement of their mechanical properties is a constant challenge in science. Numerous researchers have increasingly concentrated efforts to obtain new and more environmentally friendly materials using natural fibers, which, to be used in engineering applications, usually have to undergo thermochemical treatments. This work aims to evaluate and compare the effects of two low-cost and low-impact thermochemical treatments on Luffa cylindrica (LC) fibers to verify why different mechanical strengths are reached when applying these variations in the production of compressed earth blocks. Samples of LC fibers in three conditions were studied, LC fibers without treatment or natural LC fibers (LN), fibers treated with boiled water (LW) and fibers treated with sodium hydroxide (LS). Samples were analyzed by SEM/EDS to verify surface changes and chemical composition. The lignin, hemicellulose, amorphous and crystalline cellulose structures were determined by FTIR. XRD technique was used to determine the amorphous and crystalline phases, as well as the crystallinity index and the crystallite size. Both treatments decreased the crystallinity index, but the sodium hydroxide treatment has given a crystallinity higher than that of the water treatment. However, the water treatment cannot be ignored. Perhaps more convenient results can be achieved by varying the water treatment time.
... Alhijazi et al. [12] reviewed on recent developments in luffa natural fiber composites. In this study, it is observed that tensile strength (TS) of LNFCs increased by increasing fiber content up to 30 wt.%, but it started to decrease at 50 wt.%. ...
Article
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The current work focuses on the mechanical, fatigue, and water absorption behavior of Cissus quadrangular natural fiber (CQF) with leftover Limonia acidissima shell powder (LPA) in an epoxy matrix. Creating a sustainable biocomposite for use in high-tech engineering that uses recycled reinforcements generated from agricultural waste was the main objective of this research. An amino silane was applied to the natural fibers and particles to improve the connection between the matrix and those components. The composites were made using the hand lay method, and they were characterized using ASTM criteria. The results show that boosting the CQF volume lengthens the fatigue lifetime by as many as 36,471 life counts. The tensile strength was improved by 59% with the addition of 30 vol.% CQF. Similar morphological studies were carried out with scanning electron microscopy on the broken surfaces of composites (SEM). It demonstrates how the addition of Limonia acidissima microparticles to epoxy composites can improve the surface modification of the fiber and matrix. However, the water-absorbing behavior was only slightly enhanced by the addition of cellulosic fiber and LAP particles. The findings of this characterization study support the usage of surface-modified Cissus quadrangularis fibers and Limonia acidissima powder to create lightweight epoxy composites in a variety of industrial contexts.
... Usually, the models used for the study of the infusion process are based on Darcy's law [4,10,11], in which the characteristic parameter of the impregnation capacity of the reinforcement is represented by the permeability. In fact, the study of the resin flow inside the reinforcement allows the prediction of any defects (such as voids, dry spots, or excessive porosity) that can be generated inside the manufactured part, leading to lower mechanical performance [5,[12][13][14]. ...
Article
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In this work, a dual objective is carried out on composite materials in flax fiber and bio-based epoxy resin: to determine the process parameters and to develop a numerical model for highlighting the potential of and the limits in the production of “green” laminates through a RIFT process (Resin Infusion under Flexible Tool). For these reasons, compressibility tests were performed in order to evaluate the behavior of commercial flax woven under the vacuum bag. Subsequently, permeability tests were performed in order to evaluate the permeability curves necessary for the numerical study of the infusion process. For the numerical analyses, the commercial software PAM-RTM was adopted and validated. In this work, vaseline oil was used as the injected resin for the validation, and a bio-based epoxy commercial system was used for the study of the infusion process in a simple case study. The results were compared with a petroleum-based epoxy system typically used for infusion processes, showing the potentiality and the critical use of bio-based resins for infusion processes.
... Engineers prefer fiber reinforced polymer composites for low temperature applications due to their low cost of production [8]. However, natural fiber composites are having disadvantages due to hydrophilic nature of fibers, but coupling agents, and treatment of fibers can reduce the undesirable effects [9]. ...
Article
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Optimization of the print setting is important to achieve the desired product characteristics, which, in turn, reduce the effort of the manufacturer and the cost of production. Natural fiber reinforced PETG composites can be a potential 3D printing raw material for additive manufacturing of medical products like scaffolds, implants, prostheses, and orthoses. But the process parameters of this unique composite material need to be optimized for the fabrication of complex structures. Here, PETG-silk fibroin (PETG-SF) composites were printed by optimizing the process parameters based on single and multi-objective optimization techniques for responses such as minimum porosity, maximum dimensional accuracy, and maximum yield load. For accurate measurement of porosity and dimensional accuracy, micro-CT analysis was employed. Single objective optimization results indicate layer height and printing temperature as the highest contributing factor for maximum dimensional accuracy, maximum yield load, and for minimum porosity. Multi objective optimization result shows high temperature, low layer height, and low speed are the best settings for minimum porosity, maximum yield load, and maximum dimensional accuracy. Finally, the optimized parameters were used to print an organic shaped object to validate the results for the production of patient specific anatomically conformed prosthesis and implants. Altogether, our results show that the process parameters have a significant influence on the 3D printing of natural fiber reinforced composites and a complex structure can be effectively fabricated with the optimized parameter settings.
... The areas of application are numerous; in addition to its use as a household or cosmetic sponge, it is also used as a packaging additive [14]. In addition, the Luffa fibers are used in reinforced composites, as described [15,16]. Since the Luffa fibers, as determined in this study, have good interlocking properties in their chopped form and have a low material density of 870 kg/m 3 compared to other natural fibers (hemp: 1480 kg/m 3 ; cotton: 1550 kg/m 3 ), they can be very well suited for use as the core material of a sandwich panel [17,18]. ...
Article
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In the development of new materials, the focus nowadays is increasingly on their relevance with regard to lightweight construction or environmental compatibility. The idea of a lightweight sandwich panel was inspired by an increasing number of cosmetic accessories that use the fibers of the loofah plant, a rapidly renewable, light, fibrous raw material. The aim of the study was to develop a fiber composite panel based on the fibers of the loofah plant (Luffa cylindrica) as core material and wooden veneer as the skin layer to be used in areas of lead construction. Three different panel variations were produced for the tests, with a fiber–adhesive ratio between 1:1.05, 1:0.8, and 1:0.5. The mechanical strength (flexural strength and internal bond) and the physical properties (density and thickness swelling) were determined as a function of the fiber–adhesive composition. The results show that the flexural strength increased by approx. 400% and the thickness swelling was reduced by 10% with increasing adhesive quantity.
... 15 Furthermore, Luffa fibers are interesting alternatives to be employed as reinforcement in composite materials, since they are light and have a polyporous structure whose surface morphology can afford good adherence to polymeric matrices. 16 The structure of Luffa fibers permits penetration of synthetic resin, favoring the formation of lightweight composites with acceptable rigidity, advantageous in the production of slenderer composite materials. 17 However, there is a strong need to parameterize the effect of Luffa fibers when employed as reinforcement in composites produced with different polymeric matrices. ...
Article
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Concerns about global warming, environmental preservation, overexploitation of raw materials, and the development of new technologies are increasing. This has been attracting increasing interest in composites reinforced with natural fibers, mainly to replace synthetic materials. In this context, the present research work aimed to demonstrate the technical feasibility of the production of polyester-polymeric-matrix composites reinforced with fibers of Luffa cylindrica and a hybrid with fiberglass. The composites' physical properties (density, moisture content, water absorption, and thickness swelling) and mechanical properties (tensile, bending strength, and Rockwell hardness (RH)) were assessed. The composites were produced through cold pressing in a closed mold. The experiment was performed according to an entirely randomized design with two replicates per treatment and the means were compared by the Tukey test at 95% probability. The results demonstrated that the reinforcement with the Luffa fibers promoted a decrease in the density of the composites, with a minimum value of 1.01 g cm À3. In the assays of tensile strength, the reinforced composite presented a value of 10.20 MPa for this property, while for the bending strength, the value was 18.04 MPa. When the Luffa fibers were employed in the hybrid composite, the bending strength reached 105.12 MPa. In general, the composites reinforced with the plant fibers and the hybrid had physical and mechanical properties permitting their employment for several end-uses, according to the characteristics of each one. The new composites are partially biodegradable, sustainable, and light.
... Such new cash crop does have the capacity to enhance the economic situation in emerging countries like India [12,13]. is luffa contains more than 80 percent cellulosic agents along with lignin of around 15 percent. It has a density of 0.820 g/cm 3 and a radius ranging from 13 to 30 m [14]. e natural fibre composite material was manufactured by Mohanta and Acharya [15] using the luffa fibre mats in different layers with the epoxy as the matrix material. ...
Article
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In the current work, the experimentations have been accomplished to assess the impact of diffusing nanosilica particles in epoxy matrix on the mechanical and thermal performance of the luffa fibre reinforced epoxy composite material. The matrix and fibre composition are fixed as 80 : 20 throughout the study, and the nanosilica is disbanded in diversified volume fractions of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, respectively, while preparing luffa/epoxy/nanosilica (LES) composite samples. The mechanical characteristics, such as tensile, flexural, and impact behaviour of the composite, and the thermal properties, namely, thermal stability and thermal conductivity, are examined for the LES samples. The experiments are accomplished as per the ASTM standards. The results revealed that the assimilation of nanosilica particles in epoxy has improved the mechanical and thermal characteristics of the composite significantly. The tensile, flexural, and impact strength of the composite have been amended by 157.58%, 66.9%, and 16.5% with 1.5% addition of nanosilica in epoxy. Similarly, thermal conductivity of the composite is improved by 47.53% with the dispersion of 2.5% nanosilica in epoxy matrix. In addition, the thermal stability of the LES composite samples is substantially improved while disbanding nanosilica in epoxy matrix. However, the better results are reported for the LES composites containing 1.5% nanosilica content, compared to the next higher volume fractions of nanosilica content in epoxy matrix.
... The sponge gourd is naturally composed of interconnected fibers forming a cylindrical structure measuring ~50 mm in diameter and ~200 mm in length, as shown in Figure 1. Its chemical composition varies in the range of 57-74% cellulose, 14-30% hemicellulose, 10-20% lignin, and up to 12% other constituents such as ash and extractives [16,17]. Both due to its interconnected structure ( Figure 1) and chemical composition, sponge gourd has been investigated as a possible reinforcement for polymer composites. ...
Article
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Natural lignocellulosic fibers (NLFs) have been extensively investigated and applied as reinforcements for polymers composites owing to improved properties associated with their cost-effectiveness and their sustainable characteristics as compared to synthetic fibers. However, an intrinsic difficulty of the hydrophilic NFL adhesion to a hydrophobic polymer matrix is still a major limitation, which might be overcome via fiber surface treatments. Among the less-known NLFs, sponge gourd (Lufta cylindrica) is a promising reinforcement for polymer composites owing to its natural network of intertwined fibers. The present work investigated for the first time the influence of a chemical treatment using silane as a coupling agent for 30 wt.% sponge gourd incorporated into a polyester matrix composite. The novel composite performance was compared with that of an untreated fiber composite via X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Charpy impact tests, and thermogravimetric analyses (TGA). The XRD results revealed that the silanization increased the crystallinity index by 37%, which attests to the effective fiber–matrix interaction stretching of the C-H bond, as observed in its FTIR band. The silanization also increased the mean impact resistance by 10%. Although the temperatures associated with the beginning of the thermal degradation by the TGA were not affected, both the silane-treated fibers and composite displayed less thermal degradation compared with the untreated fibers. The scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS) results disclosed an improved sponge gourd fiber morphology after the silanization, which caused greater adherence to the polyester matrix. These results revealed a promising novel composite compared with other NLF polymer composites in engineering applications.
... Hybridization in fiber reinforcement implies the inclusion of two or more distinct (in physical attributes or type) fibers in a matrix for the development of a single composite material such as the development of a natural fiber and glass fiber hybrid reinforced epoxy composite (Ramasamy et al., 2021;Gangil et al., 2020;Shahzad et al., 2017;Ali-Eldin et al., 2021;Genc et al., 2020). Beyond distinct fibers, hybridization may involve the reinforcement of a matrix material with a single kind of fiber but with different features like diameter, length, etc. Ahmad et al., 2021;Potluri, 2019;Alhijazi et al., 2020). Different factors like fiber length, fiber percentage content, fiber orientation, fiber source, fiber treatment, fiber, etc., have shown to be of significant effect on the mechanical properties of the composite material (Yashas et al., 2018;Ansari et al., 2018;Tang et al., 2020;Todkar et al., 2019;Sun et al., 2018). ...
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The manufacturing process of a material is a strong determinant of its performance in service. Different applications like ships, wind turbine blades, oil rigs, etc. demand materials with low water absorption due to their operational environment. Previous studies have reported the water absorption behavior of cellulosic fiber-reinforced composites but the optimization of the water absorption properties of pineapple leaf/glass fiber hybrid reinforced epoxy composites by optimizing its manufacturing parameters have not been studied even with its possible wide range of application. This paper uses the Taguchi robust optimization technique and statistical analysis to optimize the water absorption properties of a pineapple leaf/glass fiber hybrid reinforced epoxy composite material PxGyE z (with x, y, and z representing the volume fraction of pineapple leaf fiber (PALF) (P), the volume fraction of glass fiber (G), and fiber length in an epoxy matrix, respectively). P15G15E 20 was the optimum having the lowest water absorption of 0.2667%. A notable observation was that fiber length had a significant contribution to the water absorption properties of the material. The interaction effect percentage contribution of fiber length with the cellulosic fiber and the glass fiber on the percentage water absorption at mean values was found to be 49.37% and 14.24% respectively. SEM and FTIR analysis showed microstructural and chemical formations that explained the water absorption behavior of the optimized hybrid composite. The percentage water absorption of the material was modeled mathematically and the equations proved to be 95.6% accurate in predicting the water absorption of the material at different combinations.
... While its mature fruit is widely used as a shower sponge and further household utilizations. The three-dimensional network structure of luffa leads to its high strength, toughness and stiffness [20,21]. Taban et al. [19] proposed replacing synthetic fibers by palm fibers in acoustic isolation applications. ...
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The present work presents an analysis of the tensile properties of Palm as well as Luffa natural fiber composites (NFC) in high density polyethylene (HDPE), polypropylene (PP), Epoxy, and Ecopoxy (BioPoxy 36) matrixes, taking into consideration the effect of fibers volume fraction variation. Finite element analysis i.e. representative volume element (RVE) model with chopped random fiber orientation was utilized for predicting the elastic properties. Tensile test following ASTM D3039 standard was conducted. Artificial neural network, multiple linear regression, adaptive neuro-fuzzy inference system, and support vector machine were implemented for defining the design space upon the considered parameters and evaluating the reliability of these machine learning approaches in predicting the tensile strength of natural fibers composites. Furthermore, BioPoxy 36 with 0.3 luffa fibers exhibited the highest tensile strength. Finite element analysis (FEA) findings profusely agreed with the experimental results. ANFIS Machine Learning (ML) tool showed least prediction error in predicting tensile strength of natural fibers composites.
... Further, in recent years, small-scaled structures have been applied extensively in engineering systems and numerous fields of studies due to their exclusive properties and mechanical characteristics [72][73][74][75][76][77][78][79][80][81]. Consequently, several studies have been reported that study the vibrational [82][83][84][85][86][87][88][89], bending [90][91][92][93][94], buckling [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109], postbuckling [110][111][112], stability [113,114], instability [115][116][117][118][119][120][121], and other mechanical characteristics of these small-scaled structures [122][123][124][125][126][127][128][129][130][131][132][133][134][135][136][137][138]. ...
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In recent years, mechanical characteristics including vibration, bending, buckling and postbuckling, stability and instability, etc. of small-scaled structures (such as micro/nanowires, micro and nano plates, micro and nano tubes, micro and nano beams, carbon micro/nano-tubes, micro and nano shells, micro and nano probes, etc.) have been broadly investigated, because of recent advances in nanotechnologies and due to their astonishing characteristics. Also, these small-scaled structures are extensively applied in several areas. However, comprehending the mechanical characteristics of these small-scaled structures is of great prominence and yet a daunting task. To understand the mechanical behaviors and capture the effects (including small-scale effect) of these different advanced small-scaled structures (at micro and nano levels), it is very essential to implement them into classical/nonclassical continuum elasticity based on a suitable classical/nonclassical elasticity formulation or theory. Thus, this work searches the literature and hereby presents an ample literature review study with a special focus primarily on the novel progress of vibration analyses of microplates and nanoplates using nonlocal/nonclassical continuum theories of elasticity. Scopus and web of science databases were used as the primary scholarly-databases to acquire the documents reviewed in the current research. Furthermore, several perspectives of classifications are considered while reviewing and grouping these acquired documents. The main purpose was to illustrate existing research trends in the vibrational analysis of small-scaled plate-based structures utilizing nonlocal plate-based theories and nonclassical continuum elasticity theories, and to provide a foundation and guidance for future research on the mechanics of small-scaled plate-based structures.
... Alhijazi and co-workers evidenced that the untreated-luffa fiber reinforced epoxy composites showed about water absorption capacity 14% higher when compared to the treated-luffa fiber-reinforced composites (Alhijazi et al., 2020b). According Ngaowthong et al. as the fiber content increases the cellulosic content and the interfacial area between the fiber and polymer also increases and hence more water diffuses into the composites with natural fiber (Ngaowthong et al., 2019). ...
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This study assesses the potential revaluation of solid waste from palm residues for use as reinforcement in acrylonitrile butadiene styrene (ABS) matrix to develop a composite filament that is more environmentally friendly. Filaments were processed using a thermokinetic mixer and then processed by a mini extruder using different fiber loadings (5, 10, 15, and 20% wt.). The effect of the fiber contents on the morphological, chemical, and thermal properties was evaluated, and environmental analysis was performed using the life cycle assessment. For a concept-proof, the materials were printed using a 3D printing pen. Pristine ABS presented no porosity, while filament composites showed a porous structure due to fiber presence and higher fiber loading induced pores with a diameter smaller than 50 μm. ABS and filament composites presented similar FTIR spectra; however, the hydrogen-bonding coefficient indicated a better fiber-matrix interaction for the ABS/15%Palm composition, increasing 42% compared to ABS. Filament's composites presented a slight decrease in thermal stability, which does not compromise its processing temperature, while the Tg presented similar values to pristine ABS. The life cycle assessment demonstrated beneficial environmental gains with fiber inclusion, especially for agricultural land occupation and ozone depletion impact categories. The filaments were successfully printed using a 3D printing pen showing the viability of using the developed filaments, and new applications may be promoted. Thus, the revalorization of palm fibers in the ABS matrix presents a low-cost alternative for filaments production and may expand 3D printing applications with more sustainable materials that could enable new applications in the additive manufacturing area.
... Awasthi 1 Department of Mechanical Engineering, Tezpur University, Napaam, Sonitpur, Tezpur, Assam 784 028, India biomedical implants for bio compatibility and its process for designing and manufacturing [4]. Alhijari et al. examined the characteristics of luffa fibre while increasing the surface area of the fibre by alkaline treatment and by lowering the moisture absorption of the fibre [5]. Koruk et al. investigated the acoustics, sound absorption, transmission losses, and damping characteristics of a luffa fibre reinforced composite [6]. ...
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Natural fibres with strong mechanical characteristics that are utilized as the reinforcing phase in natural fibre-based composites can withstand a wide range of vibrations while in service. The modal and harmonic analysis of natural fibre reinforced epoxy composites were performed to study the structural behaviour of composites with the onset of loading which can aid in identifying realistic potential applications in the field of vibration isolation, impact energy absorption and in fabrication of super-light composite panels. The effect of varying the fibre volume fraction on vibrational properties has also been investigated. The elastic characteristics were obtained analytically, whereas the frequency investigations were carried out using finite element modeling. Further-more, frequency response function (FRF) bode plots for different fibres were observed and examined in relation to various parameters. It was found that volume percentage and plate aspect ratio had a substantial impact on frequency. Lower frequencies might result in more fatigue damage to the composites.
... Because of their excellent electrical, thermal, and mechanical properties, CFRPs are commonly applied in the fabrication of polymer-matrix composites [11,[17][18][19][20]. Therefore, extensive research has been performed on the application of conventional pitchbased CFRP in improving and optimizing the characteristics of a wide variety of structures [21][22][23][24]. CFRP industry is developing by the constant growth of demand from defense and aerospace as well as small markets such as construction materials and sporting goods [24][25][26][27]. In terms of manufacturing composite/metal structures, stack-up construction is an effective joining method. ...
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In this review article, the joining of carbon fiber-reinforced polymer composite with metallic materials by using friction welding techniques was discussed and the effects of process parameters on the weld properties were evaluated. Major parameters involved in this process were plunge depth (PD), dwell time, joining time, and tool rotational speed. A successful friction joint of carbon fiber-reinforced poly composite laminate (CF-PPS)-metal was formed with an interlayer film of additional polyphenylene sulfide. In addition, a detailed overview of the friction techniques was discussed, such as friction stir spot welding (FSSW), friction stir welding (FSW), and refill friction stir spot welding (RFSSW). In this current work, we had focused on the parameters, process, and their development during friction welding of similar and dissimilar metals with CFRP joint. Regarding the FSSW review, the best tensile shear load was 7.1 kN obtained from AA5182 and CFRP at a rotational speed of 3,000 rpm and 5 s welding time. The thickness for AA5182 and CFRP are 1.2 and 3 mm, respectively. The most efficient parameters are rotational speed, PD, dwell time, and shoulder penetration depth. In addition , the heat generated during the process parameters, its influence on mechanical and microstructure properties along with the possible defects and internal cracks of the similar and dissimilar welded joints will be reviewed and discussed.
... The traditional sound absorbing materials currently applied are mainly porous or resonant sound absorbing materials [5][6][7][8][9][10][11]. And there are many reviews on the classification and theoretical model of porous sound absorbing materials as well as the factors influencing sound absorption [12][13][14][15][16]. Fiber materials can be categorized as inorganic and metal fibers, synthetic fibers, natural fibers, and nanofibers [17]. ...
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Sound absorption mechanism, material modification and structural design of various synthetic fiber materials for industrial noise reduction are reviewed in this paper for the problems of low sound absorption coefficient (SAC) and narrow frequency band of porous materials. Delany-Bazley model and Johnson-Champoux-Allard (JCA) model are widely used to predict the SAC, but they are slightly different. The air viscous effect plays an important role in Delany-Bazley model and its modified forms, while JCA model and its modified forms consider the effect of thermal conduction in addition to air viscosity. In addition, synthetic fiber materials such as polymers, metal fibers and inorganic fibers are widely used in noise reduction fields of various industries due to their unique acoustic and mechanical performance. Acoustic properties of polymers are usually improved by adding fillers, using perforated structures, gradient porous structures, and multilayer composite structures. And improving preparation method, increasing thickness of back cavity, combining different pore sizes, developing new composite materials, and adopting perforation technology can greatly promote the engineering application of metal fibers in extreme environments. Common methods to improve the sound absorption performance of inorganic fibers are to modify preparation method, increase thickness of materials and research composite materials.
... Owing to low density and outstanding mechanical properties, fiber-reinforced composites are becoming increasingly popular in various industrial sectors [1]. The manufacturing of synthetic fibers has severe environmental impact due to high power consumption, toxic nature and their contribution to ozone layer depletion have reduced the interest of scientists and engineers towards synthetic fibers [2]. The emerging trend of sustainability in the manufacturing sector has raised the demand for natural fibers in composites due to their fair specific strength, lightweight, low cost, nontoxicity, biodegradability [3] and superior damping characteristics [4]. ...
Article
Fiber metal laminates (FMLs) provide lucrative solutions for lightweight commercial aircrafts. They are a class of hybrid composites made from interlaced layers of thin metals and fiber-reinforced adhesives. The present investigation deals with the effects of hybridization and stacking sequence of aluminum sheets (A), jute (J) and Kevlar (K) fibers on the flexural, impact, hardness and tensile properties. Three distinct configurations A/K/A/K/A/K/A (I), A/J/A/K/A/J/A (II) and A/K/J/A/J/K/A (III) of FMLs have been chosen and designed for evaluation of their mechanical attributes. Comparative analysis shows that configuration A/K/J/A/J/K/A (III) offers superior results for flexural, impact, shore D hardness and tensile properties due to hybridization and appropriate stacking sequence with their maximum values as 495 N, 10.4 J, 85.4 and 325.6 MPa, respectively. Outer Kevlar layers supported by the subsequent jute fiber layers enable the configuration A/K/J/A/J/K/A (III) to resist better when subjected to high mechanical load. Moreover, the microstructural analysis revealed that the jute fibers make a stronger bond with aluminum and Kevlar fibers which prevents FMLs from delamination and early failure.
... Many studies have been carried out on different renewable sources of fibers used for the reinforcement of such composites [24][25][26][27]. Natural cellulosic fibers like sisal leaf fiber, pineapple leaf fiber, palm fiber, banana fibers have increasingly been gaining traction due to their sustainability, environmental friendliness, and low cost [28][29][30][31]. Engineers and scientists are still working on developing materials from renewable sources with a high strength-to-weight ratio so that the material's flexural performance is good when compared to its weight [32][33][34][35][36][37]. ...
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Due to their low density, natural fibers have increasingly found application in the development of systems such as wind turbine blades, airplane wing spar where flexural strength is a strong criterion for material selection. Although different researchers have studied the mechanical properties of such natural fiber composites, none has focused on the optimization of the flexural strength of pineapple leaf fiber (PALF)/glass fiber (GF) reinforced epoxy hybrid composite. This study applied the Taguchi and general regression analysis method in the optimization and modeling of the flexural strength of the PxGyEz composite. Flexural strength of 144.5 MPa at an optimum development parameter of PALF at 20% volume content, GF at 20% volume content, and fiber length of 25 mm. Analysis of variance and regression analysis was also employed to describe and model the flexural behavior of the developed composite. The PALF fiber showed to have a higher contribution to the flexural strength of the material. The equation developed to model the flexural behavior of the material showed a good correlation between the simulated value and the experimental values of the flexural strength at different combinations of manufacturing parameters.
... Many studies have been carried out on different renewable sources of fibers used for the reinforcement of such composites (Madhu et al., 2020;Rangappa et al., 2020;Reis et al., 2020;Hassan et al., 2020). Natural cellulosic fibers like sisal leaf fiber, pineapple leaf fiber, palm fiber, banana fibers, etc. have increasingly been gaining traction due to their sustainability, environmental friendliness, and low cost Alhijazi et al., 2020;Li et al., 2020;Periyasamy et al., 2020). ...
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With the continuous need for sustainable, environmentally friendly, and low-cost systems, processes, and materials, natural fibers have been a major topic of discussion in the materials science community as it has increasingly found acceptance in material development as an alternative to synthetic fibers due to environmental concerns. Although many studies have been carried out in this regard, the optimal flexural performance of pineapple leaf fiber/synthetic fiber hybrid reinforced composite has not been studied even with its promising application in aviation, health, and fitness, marine, etc. In this study, a Pineapple Leaf fiber (PALF)/Glass fiber Epoxy hybrid composite P x G y E z (with x, y, and z representing the volume fraction of pineapple leaf fiber, the volume fraction of glass fiber, and fiber length respectively) was developed and its flexural properties optimized and modeled with regards to the variable manufacturing parameters of x, y, and z respectively. For the quality characteristics (flexural strength) investigated, the Minitab®19 software was used to analyze the Taguchi robust experiment design technique on a higher the better basis. The optimum combination of the control factors was found at x = 20%, y = 20%, and z = 25mm. The optimized composite P 20 G 20 E ²⁵ possessed a flexural strength of 144.4994MPa which was only a 7.17% deviation from the predicted optimum flexural strength. Analysis of variance showed that the PALF had the highest contribution of 23.97% to the flexural strength of the P x G y E z , glass fiber 7.13%, and fiber length 12.79%. SEM Images of the PALF, glass fiber, and the fractured surface of the optimized material P 20 G 20 E ²⁵ revealed the surface structure which explained their different contribution to the flexural strength of the materials. An equation for the prediction of the flexural properties of P x G y E z was derived from the regression model and it had an approximately 77.57% agreement with experimentation.
... Luffa fibers (LFs) have a ligneous fibrous netting system, in which the fibrous cords are disposed in a multidirectional array, forming a natural mat. Besides traditional uses, the LFs are also an interesting object in polymeric studies (Mohamad et al. 2020). As a representative example, LF polymeric material is an effective biosorbent for the removal of Congo red from water (Vinod et al. 2014). ...
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Luffa cylindrica is primarily used as a vegetable, but its dry fiber can be also used as a sponge. L. cylindrica has a ligneous fibrous netting system, in which the fibrous cords are disposed in a multidirectional array, forming a natural mat. In this work, we aim to synthesize a potential material for oil spill cleanup by the graft polymerization of butyl acrylate (BA) onto Luffa fiber (LF) using 2,2 0-azobisisobutyronitrile (AIBN) as initiator. The grafting process has been controlled by monomer and AIBN concentrations, reaction time and temperature, in which the optimal condition for the highest graft yield of 40.60% is [AIBN] = 0.035 mol/L, [BA] = 1.50 mol/L, 180 min at 75°C. The graft copolymer LF-g-BA is structurally characterized by the Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. In the presence of crosslinking agent divinyl benzene, the oil sorption capacity of the synthetic LF-g-BA reaches 20.60 g oil/g sorbent for 48-h treatment. The LF-g-BA material can be seen as a potential sorbent due to its swelling property in non/ weak polar mediums and reusable feature.
... Luffa fibers (LFs) have a ligneous fibrous netting system, in which the fibrous cords are disposed in a multidirectional array, forming a natural mat. Besides traditional uses, the LFs are also an interesting object in polymeric studies (Mohamad et al. 2020). As a representative example, LF polymeric material is an effective biosorbent for the removal of Congo red from water (Vinod et al. 2014). ...
Article
Full-text available
Luffa cylindrica is primarily used as a vegetable, but its dry fiber can be also used as a sponge. L. cylindrica has a ligneous fibrous netting system, in which the fibrous cords are disposed in a multidirectional array, forming a natural mat. In this work, we aim to synthesize a potential material for oil spill cleanup by the graft polymerization of butyl acrylate (BA) onto Luffa fiber (LF) using 2,2 0-azobisisobutyronitrile (AIBN) as initiator. The grafting process has been controlled by monomer and AIBN concentrations, reaction time and temperature, in which the optimal condition for the highest graft yield of 40.60% is [AIBN] = 0.035 mol/L, [BA] = 1.50 mol/L, 180 min at 75°C. The graft copolymer LF-g-BA is structurally characterized by the Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. In the presence of crosslinking agent divinyl benzene, the oil sorption capacity of the synthetic LF-g-BA reaches 20.60 g oil/g sorbent for 48-h treatment. The LF-g-BA material can be seen as a potential sorbent due to its swelling property in non/ weak polar mediums and reusable feature.
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Sandwich composites were fabricated successfully with the balsa wood as core material and regenerated cellulose fabric bio-based polypropylene (PP) composite skins. The regenerated cellulose fabric PP composites were produced using two different methods: the conventional stacking lay-up and directly using PP pellets. Sandwich composites were made using the hot press equipment with the customized mold. The sandwich composite system and bio-composite laminate were designed to achieve very close weight to compare the key mechanical properties that each design can bear. It was evidenced from the experimental results that 416% increase in the bending load bearing property of the part can be obtained when sandwich structure was used. These experimental results were in close agreement with one of the analytical modelling utilised. The drop weight impact test results demonstrated that the sandwich specimen is capable of withstanding more than 6 kN load and absorbing the impact energy of 28.37 J.
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Pineapple crown is generally discarded as waste but constitutes an important source of lignocellulosic fibres. In this work, the effect of alkaline treatment on the chemical composition, pyrolysis kinetics, and thermodynamic characteristics of pineapple crown fibres (PCF) were investigated by chemical composition, Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), X-rays diffraction (XRD), and thermogravimetry. Chemical composition analysis indicated cellulose content increased from 18.93 to 57.00% after NaOH treatment. PCF fibre diameter was reduced from 6.1 to 4.3 μm after mercerization. The FTIR results confirmed the removal of non-cellulosic compounds. XRD analysis indicated fibre´s crystallinity index rose from 53 to 62% in reason of NaOH treatment. Thermogravimetric results confirm that alkaline-treated PCF (ATPCF) presented higher thermal stability than non-treated PCF (NTPCF). The solid-state thermal degradation mechanism for NTPCF and ATPCF occurred by the diffusion process and random nucleation, respectively. The thermodynamic parameters of NTPCF indicated that a small amount of energy is required to obtain the reaction products and thus bioenergy production from NTPCF pyrolysis will be easier, while ATPCF required more energy to initiate a degradation reaction and could be used as filler in polymeric composites.
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The water purification industry promotes biopolymers for health, safety, and ecological consideration. Biopolymers selected for environmental sustainability require lower production rates, encouraging some products to progress using new sustainable polymers and fibers. This chapter is concerns biopolymers, biofibers, and composites for water purification, tissue engineering, and other environmental uses.
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The present work is an investigation on the elastic properties of Luffa as well as Palm natural fiber composites (NFC) in high density polyethylene (HDPE) and polypropylene (PP) matrixes, taking into consideration the effect of the variation of the volume fractions (Vf) of fibers. Moreover, representative volume element (RVE) models with unidirectional and chopped random fiber orientations were utilized for predicting longitudinal, transverse, and shear moduli as well as Poisson’s ratio. Furthermore, rule of mixture (ROM), Halpin-Tsai, Chamis, and Nielsen analytical approaches were used for comparing and validating the finite element analysis (FEA) results. RVE Chopped showed highest accuracy in predicting the elastic properties of luffa and palm-reinforced thermoplastics. RVE unidirectional model findings revealed a significant agreement with analytical results.
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In order to produce bio‐nanocomposites for potential food packaging applications, nanocellulose (NC) was extracted from carrot pulp and different weight fractions of NC (5, 7, and 10 wt%) were incorporated into corn starch, either with or without thyme extract, using the solvent casting process. The particle size of the extracted NC (200–300 nm) was determined using the dynamic light scattering test, and field emission scanning electron microscopy confirmed the spherical morphology of the NC, which was successfully extracted from carrot. Fourier transform infrared spectroscopy analysis demonstrated excellent chemical interactions between the starch and NC. According to SEM images of starch‐NC nanocomposites, uniform dispersion of NC into starch was observed for all formulations. Besides, increasing the proportion of NC up to 10 wt% enhanced the tensile strength of starch nanocomposites by 280%. Since the incorporation of NC into starch increased the crystallinity index of the samples, the water absorption capacity and oxygen transmittance rate tests showed that the presence of NC reduced water and oxygen gas diffusion into the starch matrix. Furthermore, thyme‐loaded nanocomposite had remarkable antimicrobial activity, particularly in the case of gram‐positive bacteria (Staphylococcus aureus), as it expanded the bacteria's inhibitory zone by about 10 mm compared with those without an antibacterial agent. Finally, the fabricated bio‐nanocomposites exhibited balanced mechanical characteristics, perfect gas and water barrier properties, as well as promising antibacterial activity for use in the food packaging industry.
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Pineapple leaves are natural fibres with good mechanical properties which are used as the reinforcing phase in natural fibre-based composites. Composites in general sustain a variety of vibrations during their service. This investigation puts forward the modal analysis of pineapple fibre reinforced epoxy composites. The variation of fibre volume fraction has also been studied to see the effect on the mechanical properties. The elastic properties have been determined analytically, while the frequency studies have been made with the aid of finite element modelling. It was observed that volume fraction and aspect played significant effect on the frequency. Lower frequency can cause more fatigue damage to the composite.KeywordsModal analysisPineapple fibre reinforced epoxy compositeFinite element modelling
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A kind of porous sound absorber was studied to control the thermoacoustic oscillation of liquid mist flame, which combined natural fibrous materials and perforated plate. It could optimize the sound absorption characteristics of fibrous materials by adding perforated plate and air cavity. The influences of the interlayer and back cavity depth of two kinds of fibrous materials with the mass of 20, 30, 40 g were investigated experimentally in an impedance tube and applied to control the oscillating ethanol flame. The results showed that the best depth of interlayer and back cavity were 20 cm and 30 cm, respectively. The addition of two kinds of fiber sandwich structures could reduce the amplitude of the sound pressure oscillation in the combustion chamber by 89.2 % and 92.6 %, as well as 88.0 % and 91.2 % in the plenum chamber, meanwhile, restrained the flame heat release fluctuation by 73 %. It was proved that the porous sound absorber could act as a damp in the acoustic transmission path and suppress the sound source.
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The study explored the thermal insulation potential of composite material made from clay and Luffa cylindrica. Clay/ Luff cylindrica composite (denoted as Clay/L-C) was developed from natural resources. In the research, Luffa cylindrica particles of different grain sizes and different proportions were mixed with clay, and thermal evaluations were done with respect to thermal conductivity, thermal diffusivity, specific heat capacity, mass depletion with temperature, and microstructure. Two different mixture ratios, namely 4:1and 3:2 corresponding to 20 wt % and 40 wt % Luffa cylindrica particle, respectively, were used for Clay/ Luffa cylindrica combination. While Luffa cylindrica particle sizes varied from 600µm to 300µm and 150µm, the effects of Luffa cylindrica content and particle size on thermal properties were then examined. These novel composite materials developed in this study demonstrate motivating potential for enhanced thermal insulation when compared to unmodified clay. Improved thermal insulation performance indicated by thermal properties was observed for all the modified samples. This is on the account of reduced thermal conductivity of the modified samples. The best sample possessed thermal conductivity, thermal resistivity, thermal diffusivity, specific heat capacity, and porosity values of 0.216 W/mK, 462.90°C.cm/W, 0.123 mm/s ² 1.493 MJ/m ³ K, and 89.3%, respectively. Results show that Luffa cylindrica fiber can be applied as an additive for effective thermal insulation. Development in this area of study is very necessary especially as the raw materials are readily available and cost-effective.
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This study investigates the performance of thermal insulation panels composed of the natural Luffa fibres with urea-formaldehyde resin for buildings in the hot arid region. The study has been done experimentally. The work has included the collecting of Luffa fibres from local gardens in Iraq, manufacturing the specimens and measuring the thermal conductivity for different thicknesses, densities and temperatures. The results show that the thermal conductivity of Luffa/urea-formaldehyde composite ranges between 0.22 and 0.25 W/m K. Furthermore, the k-value of the panel may differ by 5–15% depending on the thickness under testing, and by 10–20% depending on the density. However, the main advantage of Luffa composites is that the k-value of the panel is not affected too much at high temperatures, where it has been increased up to 0.26 W/m K (or by 15%) as maximum by the increase of source temperature up to 80°C. This feature has encouraged the use of these panels as external insulation layers in the hot climate region. The results taken from a simulation programme have revealed that the energy saving in the cooling load due to the use of 30-mm insulated panels made of these composites and covered by reflective foils can reach up to 30%.
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In this research, a new class of partially biodegradable epoxy-based sustainable bio-composite is developed in house by using blend of luffa cylindrica (LC) and short human hair (SHH) as fiber and diverse weight proportions (0, 5, 10,15 and 20 wt.%) of incense stick ash (ISA) as filler through the conventional hand lay-up method. The presently developed hybrid natural fiber composites are characterized for their density and porosity and subsequently, investigated for their machinability through abrasive jet machining (AJM) process. Two grits of silicone carbide (SiC, 300 µm and 600 µm) and combination of aluminum oxide (Al2O3) and glass powder (90 µm) are used as the abrasives. The material removal rate (MRR) and surface roughness (Ra) of the machined surface are acquired according to Taguchi design of experiment. The significance of the control factors (type of composite, gas pressure, standoff distance and type of abrasive) is identified through ANOVA and ideal factor setting for optimum individual responses are established. Moreover, simultaneous optimization of multi performance characteristics is also attempted through Grey Relational Analysis (GRA) method. The outcomes from the confirmation runs showed an improvement in the predicted optimal machining parameters for individual as well as the multiple performance characteristic in AJM of the newly developed ISA filled LC-SHH fiber polymer composite.
Chapter
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In recent years, considerable attention has been paid to the development and use of natural fibres since they are eco-friendly, renewable and reasonably economical. Natural fibres can be suitably used as a substitute for synthetic mate�rials since they are lesser in weight and can conserve energy. They are available in abundance and incur low costs during harvesting. They happen to be budding materials, and when reinforced with a suitable matrix, they can substitute metal-based materials/composites that are presently used in aerospace and automotive industries. On the other hand, synthetic fibers are known to generate toxic byproducts and pose issues in recycling. However, natural fibers are prone to degradation when they are exposed to the external environment. The fibers pose a challenge while mixing with the polymer matrix. Surface modification of fibers is effectively carried out to overcome the weak interfacing bonding between the polymer and fibers. With the ever-growing environmental concern and excessive usage of petroleum-based reserves, the world is looking to develop composites that are compatible with the environment. In order to have a healthier impact on the environment, industries are often craving to use eco-friendly materials. The present paper focuses on the research work carried out by various investigators for synthesizing bio fiber-based composites aimed at using them in a variety of engineering fields
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This research investigates the microstructural, mechanical, and physical properties of polyvinyl chloride (PVC) matrix reinforced with coconut fiber (CF) and corn cob ash (CCA) as potential composite materials for shoe sole production. The reinforcement materials were treated and characterized before incorporation into the matrix phase (PVC). The composite samples had varying CF and CCA proportions within the range of 2-20 wt%. The results of the examinations carried out revealed that the presence of CF enhances the properties of the developed composites. Sample from 20 wt% coconut fiber-reinforced PVC had the optimum properties with ultimate tensile strength of 47.00 MPa, tensile modulus of 3.52 GPa, hardness of 81.00 HS, and wear index of 0.06 mg among all the samples produced while composites with 15 wt% CF-5 wt% CCA showed the best flexural strength of 48.60 MPa, flexural modulus of 3.77 GPa, and impact strength of 94.30 J/m 2. Hence, high proportion of CF in both composites supports the use of coconut fiber as reinforcement in PVC for shoe sole application where high flexibility and good impact resistance are essential. 摘要
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High persistence of different types of noises in the environment is a challenging problem nowadays. Many natural fiber composite works have been introduced in this line to execute the efficiency with their own compositional properties to some extent. Luffa cylindrical fiber reinforced epoxy composite has significantly enriched this noise reduction property due to its unique and complex networking structure between each of its single fiber. When a number of multilayered luffa cylindrical fibers are reinforced with a high sensitive polymer matrix like epoxy, their structural configuration modifies to that extent where the composite can function as an effective shielding material for propagation of sound through them. Although the treatment of raw fiber with alcohol blended tartaric acid and alkalization enhances the mechanical strength, alkalization treatment decreases the sound absorption coefficient, which is found to be increased significantly with that of alcohol blended chemicals. The scanning electron microscopy and Fourier transform infrared spectroscopy characterizations of both untreated and treated luffa fibers confirm the surface modification, which enables the composites to be a good acoustic material. Furthermore, thermal and electrical insulation properties are well confirmed and support the attenuation of sound propagation through the material, which decreases the thermal and electrical conductivity of the composites.
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Although there are many studies in the literature on the static mechanical properties of biomaterials such as tensile strength, the dynamic mechanical properties of biomaterials such as modal loss factors have not been investigated in detail. In this study, the Young’s moduli and damping (or loss factors) of some jute and luffa fiber-reinforced biocomposites are investigated. The effects of fiber/resin ratio and thickness on the mechanical properties of the jute and luffa composites are identified via an experimental approach. For this purpose, acoustic and structural frequency response functions of some homogeneous and hybrid jute and luffa composite plates with different fiber/resin ratios and thicknesses are measured. By analyzing the measured frequency response functions using the circle-fit method, the modal frequencies and loss factors of the homogeneous and hybrid composite plates are determined. By assuming that the homogeneous plates are isotropic, the same plates are modeled using the finite element method, and by comparing the experimental and theoretical natural frequencies, the elastic properties of the homogeneous plates are determined. In addition, the same homogeneous plates are modeled by considering an anisotropic material model, and the associated material properties are determined. By using the identified material properties, the finite element models of the hybrid composite plates are developed, and by comparing their experimental and theoretical natural frequencies, the identified elastic material properties are evaluated and validated.
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In this study, the acoustic and mechanical properties of many biofibers and their composites are presented. First, the sound absorption coefficients and transmission losses of commonly used natural fibers and their composites are presented, by clearly reporting the thickness of the samples, for three different frequency ranges (<500 Hz: low, 500–2000 Hz: medium, and >2000 Hz: high). In addition, the sound absorption coefficients (for low- and medium-frequency ranges) and noise reduction coefficients of some 40-cm-thick samples are overlaid in order to directly compare their performances. Second, the physical properties, such as the density, diameter, and length of biofibers, and mechanical properties, such as the damping (or loss factor) and Young’s modulus of biofibers and their composites, are presented in detail. For comparison purposes, the acoustic and mechanical properties of some conventional materials, such as carbon and glass fibers, are included in the tables and figures. Finally, the effects of some parameters, such as pretreatment, fiber diameter, fiber/matrix ratio, moisture content, manufacturing and machining parameters/techniques, and measurement conditions/methods, on the acoustic and mechanical properties of natural materials are presented. Furthermore, current applications and potential usage areas of natural fibers are briefly discussed.
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The lifecycle of a material and the environmental trace is becoming a dominant parameter on material's selection process. The present study focuses on the fabrication and thermomechanical characterization of fully recycled composite materials based on high-density polyethylene (HDPE) reinforced with bio-natural inclusions of carbonized Luffa cylindrica (c-LC). Materials fabrication was realized by applying the twin roll mill process, which enabled the production of a series of polymer composites with variable c-LC content. The morphological and thermomechanical characteristics were investigated by means of scanning electron microscopy and dynamic mechanical analysis, respectively. Morphological results indicate a reinforcing geometry of the inclusions, while the thermomechanical characterization verifies the reinforcement of HDPE thermoplastic with the biochar inclusions thus paving the way to the use of such fully-recycled biochar thermoplastic composite materials on structural and semi-structural applications.
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A new bioadsorbent from Luffa cylindrica and cross-linked chitosan was proposed in the present study. Luffa was used as a natural support medium for chitosan crosslinked with glutaraldehyde (LCsG) and epichlorohydrin (LCsE). Biosponges were applied to remove Allura red from aqueous solutions. LCsG and LCsE were produced using different concentrations of chitosan (1%, 3% and 5% (m v⁻¹)) and crosslinking agents (0.5%, 1.0% and 1.5% (v v⁻¹)). Based on the FT-IR spectra, functional groups characteristic of chitosan crosslinked with glutaraldehyde and epichlorohydrin confirmed the crosslinking. In addition, the biosorbent revealed highly efficient functional groups and morphology with irregularities favorable for adsorption. It was found that the increase in the percentage of glutaraldehyde and epichlorohydrin increased the sample's swelling degree, and the degree of cross-linking was greater than 80% for all LCsG. The results regarding the degree of swelling and degree of crosslinking corroborated with the evaluation of the biosponge's adsorptive potential. The Sips model predicted the equilibrium isotherms, with a maximum adsorption capacity of 89.05 mg g⁻¹ for LCsG and 60.91 mg g⁻¹ for LCsE. The new procedure was successful. Luffa was excellent support for chitosan, resulting in an attractive, low-cost bioadsorbent, preventing renewable sources.
Article
Natural fiber (NF)‐reinforced thermosetting composites exhibit excellent properties but, due to the usually hygroscopic nature of the fibers, these composites may suffer from the effects of moisture absorption. Luffa cylindrica is a NF, potentially useful in the manufacture of composite materials, but it is highly hygroscopic. A technology is developed for the fabrication of moisture‐resistant L. cylindrica‐reinforced epoxy composites and the various parameters that affect the process are investigated using long‐term moisture absorption experiments and dynamic mechanical analysis of dry and moist specimens. The technology concludes to a L. cylindrica‐reinforced bilayer matrix made of a first linseed oil‐modified precured epoxy and a final unmodified epoxy layer. This composite offers a reduced water absorbance by 33% and an almost identical Tg compared to the non‐modified epoxy reinforced with L. cylindrica. The same technology is used to manufacture water‐resistant L. cylindrica‐reinforced composites from both, environmentally friendly, matrix and reinforcement. A technology is developed for the fabrication of moisture‐resistant Luffa cylindrica‐reinforced epoxy composites and the various parameters that affect the process are investigated using long‐term moisture absorption experiments and dynamic mechanical analysis of dry and moist specimens. The technology concludes to a L. cylindrica‐reinforced bilayer matrix, made of a first linseed oil‐modified precured epoxy and a final unmodified epoxy layer, offering a reduced water absorbance by 33% without practically altering the Tg of the composite.
Article
Taking a twelve-layer RCF-SW structure as an example, the three-dimensional calculation model program of uncontrolled and MRD controlled RCF-SW structure was developed by MATLAB software. The simulation results of the model program are compared with those of the finite element model established by ANSYS software. The results show that the three-dimensional calculation model program of uncontrolled and MRD controlled RCF-SW structure can simulate the dynamic response and damping effect of the structure well. The displacement response of the RCF-SW structure controlled by MRD is smaller than those of the uncontrolled structure at the corresponding time, except for individual time periods.
Chapter
The ongoing degradation of the environment along with the necessity to fabricate the reasonable finished goods, the intellectuals are switching their interest towards the prevarication of polymeric composites, generated by using vegetable fibers as their raw materials, which are entirely biodegradable in nature. Howbeit, these vegetable fibers interact with water molecules with the aid of hydroxyl (–OH) groups present over their superficial area and thus possess hydrophilic nature. This trait of fiber leads to poor bonding between the water repelling matrix, and therefore disturbing the consonance of the polymeric composites. As a consequence, it is an attire need for the treatment of plant fiber for better adhesion between the fiber and the matrix. Several researches had been carried out on the varied approaches for the modification of vegetable fiber and the reinforced polymer composites, to ameliorate their physiochemical properties. Multifarious surface treatment methodologies like Physical, Chemical and Biological are surveyed for the effectiveness of the finished product. Chemical Treatment like Alkylation, Silane, and Acetylation etc. are compiled and presented in this chapter. But with need for less harmful and eco-sustainable process, the demand for using the chemical treatment is diminishing day-by-day and scientist are shifting towards biological and physical treatments, which are also discussed briefly. Accentuation is laid upon the future scope for employing the sustainable and green treatment for the surface modification.
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There is a remarkable increase in natural fiber-reinforced composites research over the last three decades due to their abundance, less density, biodegradability, renewable sources, and low cost. The fabrication of natural fiber composites require less energy when compared with synthetic fiber composites. Various natural fibers are available globally and have been used as reinforcements in polymer composites. These fibers provide comparable properties and can be considered as a substitute for synthetic fiber composites. The objective of this review is to analyze the various types of natural fibers used in composite fabrication along with their physical, chemical, mechanical, thermal, and tribological properties. Other important aspects such as fiber extraction, chemical treatments, manufacturing methods, hybridization, interfacial adhesion, and applications for different natural fiber composites are also discussed. The review also establishes the scope of natural fiber composites for future needs in various applications by understanding their merits and demerits.
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Natural fiber composites (NFCs) also termed as biocomposites offer an alternative to the existing synthetic fiber composites, due to their advantages such as abundance in nature, relatively low cost, lightweight, high strength-to-weight ratio, and most importantly their environmental aspects such as biodegradability, renewability, recyclability, and sustainability. Researchers are investigating in depth the properties of NFC to identify their reliability and accessibility for being involved in aircrafts, automotive, marine, sports' equipment, and other engineering fields. Modeling and simulation (M&S) of NFCs is a valuable method that contributes in enhancing the design and performance of natural fibers composite. Recently many researchers have applied finite element analysis to analyze NFCs' characteristics. This article aims to present a comprehensive review on recent developments in M&S of NFCs through classifying the research according to the analysis type, NFC type, model type, simulation platform and parameters, and research outcomes, shedding the light on the main applicable theories and methods in this area, aiming to let more experts know the current research status and also provide some guidance for relevant researches.
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There is a growing interest in the development of natural fiber composites (NFC), alternate to the existing artificial fiber composites. In recent years, the application of natural fibers as reinforcement in composite structures has received increasing attention due to their advantages of low cost, environmental friendliness and favorable biocompatibility over synthetic fiber composite materials. Every year, palm harvesting generates tons of biomass wastes around the globe, whereas these fibers have the potential to be recycled and involved in the development of palm natural fibers composites (PNFC). This paper presents a review on the recent developments in palm natural fibers composites. Various palm types and their extracts such as sugar palm, oil palm, date palm, and peach palm are included in the review. Furthermore, their physical, mechanical, morphological, electrical, and thermal properties are reviewed. It is observed that palm fibers can be applied with a variety of resins like epoxy, polyester, polypropylene, and high-density polyethylene since these PNFCs reveal a set of remarkable characteristics.
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Novel luffa fiber reinforced epoxy composites are prepared and their mechanical properties are investigated before and after chemical treatment. The unique natural knitting structure of luffa provides an excellent reinforcement to the epoxy matrix. Knowing that the fiber-matrix bond gets stronger and imparts more strength to the composite when chemical treatment is done on fibers, composites are manufactured by untreated and treated luffa fiber using epoxy as a matrix. Luffa fiber is treated using benzoyl chloride and NaOH. Tensile and flexural tests are conducted on composites to investigate the effect of chemical treatment. Test results have shown that the chemical treatment on fibers improved the tensile strength, tensile modulus, flexural strength and flexural modulus by 27.21%, 49.37%, 41.84% and 6.44% respectively. Tensile modulus of luffa fiber composite is found to be higher compared with commonly used natural fiber composites. The experimental investigation suggests that, chemically treated luffa fiber reinforced epoxy composites could be a potential lightweight material in various applications.
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This study investigates the mechanical performance and highlights the failure mechanisms of luffa/car-bon fiber hybrid polymer composites. The luffa and carbon fibers are added in the weight percentage of 40/0, 20/20, 25/15, and 15/25 with an epoxy matrix. The fabricated samples are machined as per ASTM standards. The Mechanical tests were done using the UTM machine. The tested samples have shown improvement in mechanical properties with more volume of carbon fiber with luffa fiber. The morphological images of the fractured surface are evaluated on the tensile tested specimens using a scanning electron microscope and various failure mechanisms are highlighted. This hybrid composite could find potential structural applications.
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This paper presents an investigation of impact strength of sponge gourd, coir, and jute fibers reinforced epoxy resin-based composites. Impact strength of specimens, made of composites with various proportions of wt% ratio of resin and hardener, wt% of resin and hardener, wt% ratio of sponge gourd and jute, wt% ratio of sponge gourd and coir, was measured. Design of experiment was done by Taguchi method using four control factors with three levels. Effect of the above control factors on impact strength was examined and the best combinations of control factors are advised. Confirmation test was performed by using this combination and the percentage of contribution of the above factors on impact strength was investigated by Analysis of Variance (ANOVA). Contour and interaction plots provide helpfully examines to explore the combined influences of different control factors on output characteristics. The regression equation represents a mathematical model that relates control factors with impact strength.
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Luffa fiber, glass wool (yellow) and glass fiber (white) were used into polyurethane (PU) to prepare sandwich composites. Effects of reinforcement in the composites were evaluated in terms of sound absorbance, water absorption and mechanical properties. In addition, the elastic and plastic nature along with the ignition property of the composites due to the reinforcement of the fibers was also revealed. The thermal properties of the composites were determined by differential scanning calorimetry and thermogravimetric analysis, whereas, the surface morphology of the samples before and after the ignition were examined by scanning electron microscopy (SEM). Result analysis revealed that the PU composites reinforced with glass fiber (white) showed the highest sound absorbance (21.3 dB) and tensile strength (0.96 MPa) compare to the others. The thermal stability was enhanced by 10 °C due to the reinforcement of the glass and luffa fiber. The glass transition temperature was increased significantly (58 °C) by the addition of glass fiber. The sound absorption coefficient changed from 0.21 to 0.27 due to the incorporation of the glass fiber. A large number of different-sized pores created in the composites as observed from the SEM analysis.
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The crave for a sustainable green environment and yearning for lightweight structures in the society today have prompted engineers to seek for more alternative materials to reduce the negative sides of concrete structures. Often time, composite materials or fibers are incorporated into the concrete matrix to give better performance. In this regard, the fiber enhances the concrete aggregates against stresses. This study assessed the performance of Luffa aegyptiaca (sponge gourd), a natural fiber as a polymer reinforcement in concrete for better operation. Different layering arrangements were adopted (lamina, mesh, longitudinal and disperse) to get the best fit. The compressive strength test, as well as the flexural strength test among other tests carried out, indicated that laying the fiber longitudinally in the concrete matrix can give better performance in strength. The average compressive and flexural strength of 25.8 MPa and 10.2 MPa respectively are recorded for the longitudinal arrangement which stands as the highest strength. The fiber can work well in improving concrete spalling. An extended study on the mechanical properties of the Luffa aegyptiaca to ascertain its performance is therefore recommended.
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The aim of this work is to study the mechanical behavior of a hybrid composite based on polyester thermoset matrix reinforced by a mixture of Luffa (LF) and Glass (GF) fibers. The whole volume fraction of the fibers was limited to 20 vol% in which the LF fraction was varied from 5 vol% to 20 vol%. Composites plates were prepared using the resin transfer molding (RTM) method. The morphology was studied by scanning electron microscopy (SEM), and the mechanical properties of the composites were characterized using tensile, three points’ flexural tests and hardness. Obtained results have shown that the mechanical properties of the hybrid composites were superior to those of polyester/LF composite. The mechanical properties depend on the GF fraction and on the organization of GF and LF sheets in the composite. The analytical modeling of tensile properties showed that the mechanical behavior of these hybrid composites is better described by the model of Hirsch with an adjustable value between 0.37 and 0.55. In addition, the water absorption behavior of these hybrid composites was also investigated during 200 h.
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The aim of the current work was to illustrate the effect of the fibre area correction factor on the results of modelling natural fibre-reinforced composites. A mesoscopic approach is adopted to represent the stochastic heterogeneity of the composite, i.e. a meso-structural numerical model was prototyped using the finite element method including quasi-unidirectional discrete fibre elements embedded in a matrix. The model was verified by the experimental results from previous work on jute fibres but is extendable to every natural fibre with cross-sectional non-uniformity. A correction factor was suggested to fine-tune both the analytical and numerical models. Moreover, a model updating technique for considering the size-effect of fibres is introduced and its implementation was automated by means of FORTRAN subroutines and Python scripts. It was shown that correcting and updating the fibre strength is critical to obtain accurate macroscopic response of the composite when discrete modelling of fibres is intended. Based on the current study, it is found that consideration of the effect of flaws on the strength of natural fibres and inclusion of the fibre area correction factor are crucial to obtain realistic results.
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Reinforcing polymers with nanofillers is an advanced approach to improve and manage the thermal behaviors of polymeric nanocomposite materials. Among the proposed nanofillers, graphene and carbon nanotube (CNT) with superior thermal conductivity are two advanced nanofillers, which have extensively been utilized to enhance the heat transfer responses of host polymeric materials. In this work, the impacts of randomly oriented graphene and CNT to steady state and transient heat transfer behaviors of functionally graded (FG) nanocomposite cylinders have been investigated using an axisymmetric model. Nanocomposite cylinders have been assumed to be under heat fluxes, heat convections or temperatures as different types of thermal boundary conditions. The thermal properties of the resulted nanocomposite materials are estimated by micromechanical model. Moreover, the governing thermal equations of axisymmetric cylinders have been analyzed using a highly consistent and reliable developed mesh-free method. This numerical method predicts temperature fields via MLS shape functions and imposes essential boundary conditions with transformation approach. The effects of nanofiller content and distribution as well as thermal boundary conditions on the heat transfer responses of nanocomposite cylinders are studied. The results indicated that the use of nanofiller resulted in shorter stationary times and higher temperature gradients in FG nanocomposite cylinders. Moreover, the use of graphene in nanocomposites had stronger impact on thermal response than CNT.
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Application of natural fibre reinforced polymer composites (NFPC) in transportation diligences has become inexorable due to light weight, superior properties, less cost of production and suitability to many products. But the main disadvantages of employing these fibers are their poor dimensional stability and high hydrophilic nature. Interfacial bonding between the fiber and matrix plays a vital role in deciding the mechanical characteristics of composites. Various chemical cures are applied for enhancing the fiber-matrix adhesion which ends up in better mechanical characteristics of the composites. The current aerospace and automotive industries are looking to change the conventional materials which are high density material to composite material for reducing the overall weight of the vehicle to increase its performance. This review paper provides a vast overview on natural fiber reinforced composites, various chemical treatments applied and applications of those composites.
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In this study, composites of poly (hydroxybutyrate-co-valerate) (PHBV) with untreated luffa fibers (ULF) and NaOH-H2O2 treated luffa fibers (TLF) were prepared by hot press forming. The properties of luffa fibers (LFs) and composites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and other analysis methods. Results showed that pre-treatment effectively removed pectin, hemicellulose, and lignin, thus reducing the moisture absorptivity of LFs. The flexural strength of TLF/PHBV was higher than that of ULF/PHBV. With 60% LF content, the flexural strengths of ULF/PHBV and TLF/PHBV reached 75.23 MPa and 90.73 MPa, respectively, 219.7% and 285.6% more than that of pure PHBV. Water absorptivities of composites increased with increase in LF content. Water absorptivity of TLF/PHBV was lower than that of ULF/PHBV. The flexural strengths of composites decreased after immersion in water at room temperature. Meanwhile, flexural strength of TLF/PHBV was lower than that of ULF/PHBV. Pretreatment of LFs effectively improved the bonding between fibers and PHBV, resulting in enhanced and thus improved the moisture resistance of composites.
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Sustainability is one of the significant goals in the evaluation and promotion of building materials in the current society. This paper presents an evaluation of the potential of natural fiber for building acoustics absorber. This was done by comparing all aspects of sustainability including economy, social and environmental needs between the natural and synthetic fibers. Some features of natural fibers such as light weight, bio-degradability, low-cost, carbon-dioxide neutral, low consumption of energy and health aspects has been the major factors that contributed to its use in many construction applications. In addition to that, previous researches showed that sound absorbing materials with natural fibers have good acoustic properties in high frequency range similar with those synthetic fiber. However, high water absorption, prone to termite attack, less fire resistance and low strength are remaining the issues militating against the natural fiber for building acoustic absorber. Despite that, natural fibers have already been proven alternatives to synthetic fiber in building acoustic absorber thereby alleviating some sustainability issues associated with the use of synthetics materials in building acoustics.
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This study examines the effect of addition of Luffa cylindrica fiber (LCF) and Luffa cylindrica particulate (LCP) on the properties of epoxy resin. Luffa cylindrica fiber treated with 8% NaOH and of 2, 4, and 6% weight fraction was used to reinforce epoxy resin via hand lay-up method. Hybridization of the fiber and particulate was also done with the particulate having a constant weight fraction of 10% whereas the fibers were varied as in the mono-reinforced Luffa cylindrica fiber composite. The samples were machined for mechanical and microstructural analysis. Result showed that addition of the reinforcement led to an improvement in mechanical properties. However, the hybrid was seen to showcase better properties compared to the fiber-reinforced composite with the hybrid sample of composition 4 wt% LCF and 10 wt% LCP exhibiting the highest tensile and flexural strength of 13.489 MPa and 20.3 MPa, respectively. Microstructural analysis showed excellent homogeneity with few voids and better adhesion between the reinforcement and matrix. These results show that this composite can find application in the interior and exterior parts of automobiles as well as in household wares like flower pots.
Article
Luffa fibers were silane functionalized using varied concentrations of 3-aminopropyl trimethoxysilane (APTMS) in methanol solution to investigate the relationship between the concentration of silanizing agent and the effective degree of silanization of luffa fibers. The aim of the present work was to identify the optimal silane concentration to adequately functionalize the luffa fibers and to investigate its influence on the properties of luffa-epoxy composites. The degree of silanization was controlled by varying the weight ratios of fiber and APTMS (1:0.5, 1:1, 1:1.5, and 1:2). The optimal degree of silanization was confirmed by testing the mechanical, thermal, and flammable properties of functionalized luffa fiber-filled epoxy matrix composites. The composite with 1:1.5 w/w silane functionalization exhibited a maximum tensile strength of 18.4 ± 0.94 MPa. The interfacial adhesion of the prepared samples is investigated through morphological studies. Thermal studies indicated that thermal stability increased with an increase in silanization. TGA analysis revealed that the silane treatment improved the thermal profile of the composites with initial degradation above 240 °C. The storage modulus of composites decreased with an increase in temperature with a 3-stage pattern of the slope. The storage modulus and Tg increased with an increase in silanization degree and the loss modulus peak shifted towards higher temperature with the increase in silanization. Flame retardant studies show that the optimized composite exhibits V-1 rating suggesting the suitability of the prepared composite for various applications.
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The current investigation deals with the nonlinear oscillation response of conical microshells made of a composite material with functional graded (FG) in-plane heterogeneity is studied in the presence of the size dependency. To accomplish this purpose, various types of homogenization schemes including Voigt model, Reuss model, Mori-Tanaka model, and Hashin-Shtrikman bounds model are employed. The size-dependent characteristics are taken into consideration on the basis of the modified couple stress theory of elasticity within the framework of the higher-order shear deformation shell theory. The couple stress-based differential equations of motion are constructed via the Hamilton's principle. An efficient numerical solution methodology adopting generalized differential quadrature (GDQ) method together with the pseudo-arc technique is put to use to obtain the modified couple stress-based nonlinear frequency of homogenized FG composite conical microshells. It is demonstrated that by increasing the value of the maximum shell deflection, the couple stress type of size effect plays more important role in the nonlinear vibration response of FG composite conical microshells. Additionally, it is indicated by changing the boundary conditions from simply supported one to clamped one, the influence of couple stress size dependency decreases.
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The present work aims to investigate the effect of nanofiller, lead oxide on the mechanical, thermal, and water intake behavior of luffa fiber-reinforced epoxy polymer matrix composites. Filler material PbO of 20 nm was added in different weight proportions along with luffa fiber to the matrix and the compression molding technique was used for the fabrication of the composite laminates. Tensile, flexural, and impact properties were studied on the prepared samples. The influence of lead oxide on glass transient temperature (Tg) and the curing of epoxy were also studied using the Differential scanning calorimeter. The optimum mechanical and thermal properties were observed on the addition of 1.25 wt. % of nanofiller. The morphological images show various defects like interfacial behavior, fiber pulls outs, voids, and internal cracks, and these were examined using a scanning electron microscope. Hence the present investigation showed that the addition of nanofiller could enhance the mechanical strength of the natural fiber composite. Further, it enhanced the moisture resistance and thus could find potential structural and packaging applications.
Article
This paper proposes the use of a porous core between layers of laminated composite plates to examine its effect on the natural frequencies of the resulted porous laminated composite sandwich plate (PLCSP) resting on a two-parameter elastic foundation. Moreover, it has been suggested that the dispersion of porosity has two different functionally graded (FG) patterns which are compared with a uniformly dispersed (UD) profile to find their best vibrational efficiency in the proposed PLCSPs. In FG patterns, two types of dispersions, including symmetric (FG-S) and asymmetric (FG-A) patterns have been considered. To derive the governing Eigen value equation of such structures, the first order shear deformation theory (FSDT) of plates has been employed. Accordingly, a finite element method (FEM) is developed to solve the derived Eigen value equation. Using the mentioned theory and method, the effects of porosity parameters, fiber orientation of laminated composite, geometrical dimensions, boundary conditions and elastic foundation on the natural frequencies of the proposed PLCSPs have been studied. It is observed that embedding porosity in core layer leads to a significant improvement in the natural frequencies of PLCSPs. Moreover, the natural frequencies of PLCSPs with FG porous core are higher than those with UD porous core. (PDF) The effect of embedding a porous core on the free vibration behavior of laminated composite plates.
Article
The present study deals with the size-dependent nonlinear buckling characteristics of conical microshells made of functionally graded (FG) composite materials under uniform hydrostatic pressure based upon the modified couple stress theory of elasticity. Accordingly, a modified couple stress-based shell model within the framework of the higher-order shear deformation shell theory and von Karman geometrical nonlinearity is constructed. Using the virtual work's principle in conjunction with the adjacent equilibrium criterion, the non-classical governing differential equations are established. The material properties of FG composite conical microshells are estimated on the basis of different homogenization schemes. To solve the size-dependent nonlinear problem, the generalized differential quadrature discretization pattern together with the Galerkin technique is employed. It is seen that among various types of homogenization scheme, the Voigt and Reuss models represent, respectively, the overestimated and underestimated critical buckling pressures. Also, it is found that for a FG composite conical microshell with higher semi-vertex angle, the influence of the material property gradient index on the nonlinear critical buckling pressure diminishes. In addition, it is observed that the couple stress size dependency plays more important role in the nonlinear buckling behavior of FG composite conical microshells with lower ratio of R1/h. These patterns are the same for all types of boundary conditions.
Article
The prime objective of the present investigation is to predict the shear buckling characteristics of skew nanoplates made of a functionally graded material (FGM) in the presence of surface stress effect. For this purpose, the Gurtin-Murdoch surface theory of elasticity is applied to the higher-order shear deformation plate theory within the framework of the oblique coordinate system. Different types of the homogenization scheme including Reuss model, Voigt model, Mori-Tanaka model, and Hashin-Shtrikman bounds model are taken into consideration in order to extract the effective mechanical properties of FGM skew nanoplates. The Ritz method using Gram-Schmidt shape functions is utilized to obtain the surface elastic-based shear buckling loads of FGM skew nanoplates. It is indicated that by increasing the value of the index associated with the material property gradient, the significance of the surface stress type of size effect on the shear buckling behavior of a FGM skew nanoplate improves. Moreover, by changing the boundary conditions from simply supported ones to clamped ones, the influence of the skew angle on the surface elastic-based shear buckling load of a FGM skew nanoplate increases. Also, it is illustrated that by increasing the width to thickness ratio of a skew nanoplate, the free surface area increases which results in to enhance the effect of surface residual stress on its shear buckling characteristics.
Article
Design and development of new biomaterials has become a necessity due to adverse effects of chemical materials on people and nature. As the mechanical properties of biomaterials are not as good as those of chemical materials, their different configurations should be developed and tested before considering them for practical applications. Acoustic and mechanical properties of homogenous and hybrid jute and luffa biocomposites are investigated here. Homogenous and hybrid composites using jute and luffa fibers and epoxy are designed and manufactured and methods for identification of the acoustic and mechanical properties are summarized. Acoustic and structural frequency response functions are measured using homogenous and hybrid composite plates to determine their natural frequencies and loss factors. Using the experimental modal parameters of the plates and their theoretical models, elasticity moduli of biomaterials are determined. The acoustic absorption properties and transmission losses of homogeneous and hybrid composites are determined using impedance tube method. Results show that homogenous and hybrid jute and luffa composites can have moderate absorption coefficients (0.1 for a thickness of 4 mm) and superior damping performance of luffa and stiffness property of jute can be used together to produce hybrid composites with high damping (2.2–2.6%) and elasticity modulus (3–5 GPa).
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The vibration frequencies of plant fibre (Luffa cylindrical sponge) reinforced composite structure has been studied in this article Initially, a simulation model of Luffa fibre reinforced polymer composite plate has been developed through the commercial finite element analysis package. Further, the finite element frequency solutions are compared with own experimental frequency data (recorded using the in-house fabricated Luffa fiber composite) for the validation purpose. The current analysis mainly performed on two composite plate fabricated using the different weight of fibre (no fibre and 6.4%). Moreover, the simulation frequencies are computed using the experimental elastic properties of Luffa fibre polymer composite plate. After the necessary verification, the simulation model has been extended to explore the influence of various structural parameters on the free vibration frequency.
Article
Traditional printed circuit board (PCB) laminates such as FR4 types are formed using epoxy resin and glass fiber. The most important problem with waste PCB laminates is that their recycling cycle is too long. Here, we aimed to show whether it is possible or not to use plant-based fibers instead of petroleum-based fibers. In this study, we have fabricated an alternative eco-friendly Luffa fiber reinforced/epoxy PCB (Luffa-PCB) laminates using luffa fiber instead of glass fiber. We examined the properties of Luffa-PCB laminates for potential applications as PCBs in terms of frequency dependence of dielectric permittivity, capacitance, ac conductivity, impedance, and electric modulus by using impedance spectroscopy method in a frequency ranging from 10 Hz to 10 MHz. Furthermore, we investigated the electrical resistivity properties of Luffa-PCB laminates using electrometer/high resistance meter and resistivity test fixture. All results were compared with commonly used FR2 and FR4 type PCB laminates. According to the results obtained, it has been found that the produced Luffa-PCB laminates have adequate properties as an alternative to traditional laminates. Thus, a significant step is taken to solve the recycling problem by using plant-based fibers instead of glass fiber.
Article
Natural fiber reinforced composites have occupied more applications in major engineering fields due to their improved mechanical properties and eco-friendly nature. In this work, the consequences of calcium carbonate (CaCO3) as filler on thermo-gravimetric (TG) and Dynamic Mechanical (DM) properties with various proportions along with coir/luffa cylindrical (C/L/C) hybrid epoxy composites were investigated. Different proportions of the CaCO3 (0, 2 and 4%) – C/L/C hybrid composite samples were fabricated using hand layup technique. TG and DM analysis were carried out on the fabricated composite specimens and the results like thermal stability, storage modulus, loss modulus and loss factor (Tanδ) of the composite specimens were evaluated and compared with filler less composite specimens. It was observed that 2 g of CaCO3-C/L/C hybrid composites have high thermal and dynamic mechanical characteristics as compared to the other composite samples. Moreover, Cole-Cole plot revealed excellent bonding among the fibre, filler and matrix. Based on the obtained results, it can be concluded that the composites with 2 g filler content can be used in major engineering applications due to their improved dynamic mechanical properties.
Article
In this work, the characteristics of a vegetable fibre (luffa cylindrica) polyester composite are studied as a function of fibre surface treatment (with NaOH, Ca(OH)2 and silane) and fibre content (30%, 40% and 50%). Composites were prepared through compression moulding and characterized with thermogravimetric and dynamic-mechanical analyses. Higher storage modulus was obtained with Ca(OH)2 treated composites, reaching nearly 70% increase. Higher loss modulus (E”) was noted in for silane treated fibre (at 50%) and a high peak in damping factor was noted for Ca(OH)2 treated fibre (at 50%). Cole-cole plot showed highest homogeneity for the Ca(OH)2 treated composites. Electron microscopy revealed the fracture modes in static tested composites. The general properties obtained indicate that the composites can only be used for low loading applications.
Article
Natural fiber hybrid composites were prepared by Hand layup technique by reinforcing coir, silk squash, and CaCO3. Both coir and silk squash is maintained constant weight proportion of 10 wt. % and 5.7 wt. %, respectively, whereas as CaCO3 is varied with three different proportions (0, 2 and 4 wt. %). Mechanical and dielectric properties were evaluated on the fabricated composite samples. Influence of filler content on adhesive bonding of the fractured composite samples was studied using Scanning Electron Microscopy (SEM). Higher filler content in the composite attained high mechanical properties, similar with the dielectric properties as well. The potential applications of the present fabricated composite samples are found to be increase in automobile and building industry in near future.
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The thermomechanical and thermo-hydro-mechanical treatments in Luffa cylindrical fibers were evaluated. The treatments comprised the hot pressing of the fibers in the dry condition (thermomechanical) and in the saturated condition (thermo-hydro-mechanical) with the objectives of porosity reduction and increase of modulus of elasticity of the fibrous material. The thermomechanical treatments were performed at 25, 120, 160 and 200°C. Tensile strength, moisture absorption, scanning electron microscopy (SEM), X-ray diffraction and thermogravimetric analysis were carried out to follow the effect of the proposed treatment. After treatment, the fibers presented a higher modulus of elasticity and lower moisture absorption. The best results were achieved for the saturated fibers pressed at 160ºC, as they presented a 95% increase in the modulus of elasticity and a 22% decrease in the moisture absorption in relation to the compressed fiber at room temperature. When exposed to heat and humidity, the densified sample showed a tendency to return to its original shape. The achieved results show that Luffa cylindrical fiber is suitable and possibly to be used in composites for engineering applications and indicate the high potential of thermomechanical and thermo-hydro-mechanical treatments to improve the properties of this natural fiber.
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Present work concentrates on modal parameters of laminated composite plates composed of natural fibers reinforced with unsaturated polyester resin. The selected jute and ramie fibers underwent alkaline treatment to improve mechanical properties. Upon compression molding, the laminated composite plates such as ramie/polyester (R plate), jute/polyester (J plate) and combination of ramie and jute (RJ plate) are fabricated. The physical, mechanical and elastic properties are calculated as per ASTM standards. Using obtained elastic properties, the free undamped vibration analysis of composite plates are computed using finite element software ANSYS 18.1 for trapezoidal plates, with respect to a/b = 1 and 2, c/b = 0.25 to 1 and a/h = 50. The natural frequency and mode shape of the plates are obtained for various boundary conditions such as CFFF, CFCF, CCCC, SFSF and SSSS (C-Clamped, F-Free and S-Simply supported). The dimensionless frequency and mode shapes of R, J and RJ plates are compared with literatures which are in good agreement.