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Mechanical properties of luffa sponge
Abstract
The paper presents the first scientific study of the stiffness, strength and energy absorption characteristics of the luffa sponge with a view to using it as an alternative sustainable engineering material for various practical applications. A series of compression tests on luffa sponge columns have been carried out. The stress-strain curves show a near constant plateau stress over a long strain range, which is ideal for energy absorption applications. It is found that the luffa sponge material exhibits remarkable stiffness, strength and energy absorption capacities that are comparable to those of some metallic cellular materials in a similar density range. Empirical formulae have been developed for stiffness, strength, densification strain and specific energy absorption at the macroscopic level. A comparative study shows that the luffa sponge material outperforms a variety of traditional engineering materials.
... Fischer et al. [13] worked with the casting process to develop metallic foams, and Schӓfer et al. [1] analyzed the feature through numerical modelling of foam samples (kelvin cell). The first scientific study on luffa [14], a lightweight open-cell cellular structure, reveals that it has a constant plateau over a long strain range, which is one of the prerequisites for being an ideal energy absorber. The densification strain and energy absorption efficiency are 0.57 and 0.45 (approx.), ...
... respectively. The study by Shen et al. [14], also demonstrated that under uniaxial compression, its energy absorption per unit mass is identical to that of other aluminum foams and most polymer foams. Finally, they proposed this for alternative packaging materials due to their extremely lightweight nature, environment-friendly behavior, and sustainability. ...
... The energy absorption efficiency (25.61%) and the densification strain (0.56) are both lower for the solid structure than the biomimetic structure, i.e., 38.47% and 0.8, respectively. These two data are comparable with the literature (luffa [14] and durian [18]). Finally, it is noteworthy that the mass and volume of the solid structure (0.81 g and 300 mm 3 ) and is considerably higher than that of the hollow (0.08 g and 31.09 ...
Different biological systems and objects have existed in nature in a best-fitted way for millions of years under various environmental conditions. These objects, with their extraordinary features, can be the design inspiration for engineers and scientists. Energy absorption characteristic is an important parameter for structures that safeguard human life and precious goods from accidental loading conditions. Moreover, sandwich panels, known for their excellent weight-to-stiffness ratio, are widely used for tailoring this purpose. In this study, a bio-inspired sandwich panel has been developed, drawing inspiration from the spiky structure of the outer shell of the tropical Jackfruit. The energy absorption characteristics and some other parameters are investigated using a computational approach and compared with two other types of structures (i.e., solid and hollow structures). The computational approach primarily entails a nonlinear static analysis that emulates a quasi-static compression test. Compared to the solid structure, the proposed biomimetic structure exhibits a mass and volume reduction of approximately 82% and 83%, respectively. The densification strain is also higher than the solid one, which ultimately increases the effective crushing distance for the proposed structure. In addition, the energy absorption (EA) and specific energy absorption (SEA) of the proposed biomimetic structure are approximately 4 and 2.5 times higher than those of the hollow structure. However, further investigations are required to justify its feasibility as an efficient energy absorber.
... Based on the cases where it is cultivated, it will be more compact and thinner from 0 to 300 m above sea level and lower compact above 300 m. The mechanical examinations of loofah samples have been examined in many methods for illustrative purposes using theoretical concepts of natural cellular components with empirical functions that modify experimental compression outcomes [29,30]. The outcomes exhibit ranges of quantities in different characteristics of low or high-density loofah columns [31]. ...
... The outcomes exhibit ranges of quantities in different characteristics of low or high-density loofah columns [31]. Other outcomes include examining compression over small-block-shaped specimens, explaining good energy absorption outcomes on various schemes, or testing single fibers to collect their strain, tensile strength, modulus, mean diameter, yield strength, and some pores [29][30][31][32]. The various directions that loofah fibers exhibit in their fruit shape pursue three circumferential, longitudinal, and radial orientations, plus one continuous and central long division [29][30][31]33]. ...
... Other outcomes include examining compression over small-block-shaped specimens, explaining good energy absorption outcomes on various schemes, or testing single fibers to collect their strain, tensile strength, modulus, mean diameter, yield strength, and some pores [29][30][31][32]. The various directions that loofah fibers exhibit in their fruit shape pursue three circumferential, longitudinal, and radial orientations, plus one continuous and central long division [29][30][31]33]. These fibers are exhibited in the core, inner, outer, and internal parts in that they arrange their scheme, interconnecting to produce chains as micro-tissues [28]. ...
The physical, mechanical, and thermal characteristics of loofa fiber-alumina (Al2O3) and loofa fiber-aluminum silicon carbide (Al-SiC) reinforced with epoxy, vinyl-ester, and polyester hybrid composites were experimentally studied. The polymer hybrid laminates were fabricated using an ultrasonication probe-assisted wet-layup technique. The outcomes show that flexural, impact, and tensile characteristics were higher for loofa fiber-Al-SiC reinforcement than other samples due to minimal voids and uniform dispersion of fillers within the matrices as observed from scanning electron microscope (SEM) images. Minimum water absorption and thickness swelling characteristics were examined for the composite specimen reinforced with loofa fiber-Al-SiC fillers. Thermo-gravimetric analysis (TGA) was performed, and the laminate was observed to be thermally stable up to 436 °C. Also, forecasting models were simulated using an artificial neural network (ANN) to perceive schemes in data by varying certain factors. The outcomes collected signified that loofa fiber-Al-SiC-based laminate could substitute traditionally applied materials and provide real-world directions. A one-way ANOVA (Analysis of Variance) technique was performed to check the significance between the physical, mechanical, and thermal characteristics of developed polymer hybrid composites and found significant under a 95 % confidence level. Based on the results, the loofa fiber-Al-SiC reinforced polymer hybrid laminate exhibited improved tensile, impact, and flexural characteristics along with remarkable thermal stability, recommends multi-faceted applications in industries demanding lightweight yet strong materials like automotive and aerospace field, where structural integrity and decrement in weight are dominant.
... The mechanical properties of poriferan skeletons [45] and sponge-like materials of non-poriferan origin [46] are rarely studied comparatively, and only a handful of studies exist [47][48][49]. These can be contrasted by the type of organic matrix exhibited, such as proteinaceous spongin-based skeletons of commercial bath sponges [48], collagen sponges [50], wood sponges [51], as well as cellulose-based Luffa fruit (i.e., Luffa aegyptiaca) sponges [49]. ...
... The mechanical properties of poriferan skeletons [45] and sponge-like materials of non-poriferan origin [46] are rarely studied comparatively, and only a handful of studies exist [47][48][49]. These can be contrasted by the type of organic matrix exhibited, such as proteinaceous spongin-based skeletons of commercial bath sponges [48], collagen sponges [50], wood sponges [51], as well as cellulose-based Luffa fruit (i.e., Luffa aegyptiaca) sponges [49]. A direct comparison between the mechanical properties of the sponges (Porifera) investigated in this study is not possible due to significant differences; however, as an example, Rhopaloeides odorabile marine sponges with spongin skeletons studied by Louden and coworkers [48] showed an elastic modulus of less than one megapascal (838.7 ± 53.5 kPa). ...
... This further confirms the unique nature and superior mechanical properties of the chitinous Verongiida demosponges under study. For example, the elastic modulus (nanoindentation) of the A. aerophoba demosponge skeleton, still containing bromotyrosines, is approximately 2.6 GPa ( Figure 5), which is half of the bush crickets' Mecopoda elongata acoustic tracheae (5.2 GPa) [29] and scorpion (Scorpio palmatus) tarsus exoskeleton (5.4 GPa) [49]. However, this value falls within the range of, for example, chitin films [28,52,53] but below, for example, crustacean nanofibres isolated from the American lobster (Homarus americanus) (Young's modulus: 7.3 GPa) [54]. ...
Skeletal constructs of diverse marine sponges remain to be a sustainable source of biocompatible porous biopolymer-based 3D scaffolds for tissue engineering and technology, especially structures isolated from cultivated demosponges, which belong to the Verongiida order, due to the renewability of their chitinous, fibre-containing architecture focused attention. These chitinous scaffolds have already shown excellent and promising results in biomimetics and tissue engineering with respect to their broad diversity of cells. However, the mechanical features of these constructs have been poorly studied before. For the first time, the elastic moduli characterising the chitinous samples have been determined. Moreover, nanoindentation of the selected bromotyrosine-containing as well as pigment-free chitinous scaffolds isolated from selected verongiids was used in the study for comparative purposes. It was shown that the removal of bromotyrosines from chitin scaffolds results in a reduced elastic modulus; however, their hardness was relatively unaffected.
... The growing demand for sustainable materials across various industries has spurred research on plant-based fibers as viable alternatives to synthetic materials, positioning sponge gourds (Luffa cylindrica) as a promising option for industrial applications. This natural fiber is characterized by its spongy structure, durability, biodegradability, and qualities that make it suitable for use in sectors such as construction, automotive, and cosmetics [1]. Additionally, its resilience and natural origin highlight it as an eco-friendly alternative that contributes to sustainability, driving studies focused on optimizing its cultivation in diverse environments [2,3]. ...
... Studies by Li et al. [7], Chen et al. [22], and Katre et al. [23] emphasize the importance of organic amendments in enhancing agricultural productivity, which is consistent with the findings of this study. In E-1, where SOM was applied, fruit damage caused by pests and environmental stress was reduced by 45%, aligning with the findings of Shen et al. [1] and Silva et al. [12], who associate organic matter-rich substrates with improved plant resistance. Furthermore, the environmental variability observed across the three cultivation sites (E-1, E-2, and E-3), particularly in soil type and altitude, highlights the need for agronomic practices tailored to local conditions. ...
This study evaluated the successful establishment of sponge gourds (Luffa cylindrica) through direct seeding under open-field conditions in a subtropical climate in Mexico. Three experimental sites, E1, E2, and E3, located in different rural communities with distinct altitudes and soil types (Luvisol and Andosol) were evaluated. E1 was enhanced with an organo-mineral substrate (SOM), while E2 and E3 served as controls without SOM application. Seeds from a single fruit were used for planting following standardized cultivation practices. Each experimental plot contained a total of 10 plants arranged in 10 rows with one plant per row. Yield variables, such as fruit count, length, diameter, weight, and seed quantity, were measured. E-1 exhibited superior growth, yielding 5–20 fruits per plant, with lengths of 9–15 cm, diameters up to 6.2 cm, and weights reaching 370 g, significantly surpassing E-2 and E-3. Kruskal-Wallis tests confirmed significant differences among the plots, indicating that seed germination enhanced by SOM in E-1 promoted improved growth characteristics. The production cost per fruit was 12.70 in E-2, and $13.60 MXN in E-3. These results support sponge gourds as a viable crop option for small- and medium-scale farmers in subtropical areas, offering both economic and environmental benefits.
... The aforementioned stiffness, strength and energy absorption attributes cover a rather wide space, which however has not been associated with the density of the corresponding base material. Subsequently, mechanical attributes and density values are associated in Ashby-type comparisons with the performance of a diverse array of natural, metallic, polymeric and biological materials [68,69,70]. ...
... The strength of the helically-braided load carrying materials under investigation (light blue region) is situated at the intersection of natural cellular and biological materials. The reported strength values for sponge or natural shell type structures, such as the Durian shell of Luffa sponge [71,70] are substantially lower than those of the weakest structural designs probed (PL and GF structures), with strength values in the order of 10 MPa that is comparable to the values reported for skin (Fig. 8b). Coconut and manila-fiber based structures yield strength values that are substantially higher. ...
... The energy absorption of the loofah sponge specimen was calculated using the integral function of the mathematical module in Origin 2021 software, with the compression stroke set to 24 mm (i.e., 60% of the height), as shown in Table 3. The results show that the specific energy absorption of loofah sponge is comparable to that of aluminum foam and most polymer foams, demonstrating excellent energy absorption performance, and the energy absorption of the loofah sponge's overall structure tends to decrease as the density decreases; however, it is not solely determined by the density [28,29]. Other factors also influence energy absorption, which may be attributed to variations in the structural sizes of the fibers across different regions of the sponge. ...
... The energy absorption of the loofah sponge specimen was calculated using the integral function of the mathematical module in Origin 2021 software, with the compression stroke set to 24 mm (i.e., 60% of the height), as shown in Table 3. The results show that the specific energy absorption of loofah sponge is comparable to that of aluminum foam and most polymer foams, demonstrating excellent energy absorption performance, and the energy absorption of the loofah sponge's overall structure tends to decrease as the density decreases; however, it is not solely determined by the density [28][29]. Other factors also influence energy absorption, which may be attributed to variations in the structural sizes of the fibers across different regions of the sponge. ...
The loofah sponge has a complex, three-dimensional, porous mesh fiber structure characterized by markedly low density and excellent vibration isolation properties. In this study, loofah sponges made from dried Luffa cylindrica were divided into two components: the core unit and the shell unit, which were further subdivided into five regions. Static compression performance tests and vibration isolation analysis were conducted on the loofah sponge and its individual parts. Scanning models of the loofah sponge were generated using the RX Solutions nano-CT system in France, and finite element analysis was performed using the ANSYS Workbench. This study focused on the vibration isolation performance of the loofah sponge, examining energy absorption and isolation, as well as the vibrational strength of its isolation performance. The goal was to explore the functions and vibration isolation mechanisms of its different components. The results demonstrated that the loofah sponge structure exhibits rigid–flexible coupling, with the coordinated action of multiple parts producing highly effective energy absorption and isolation of the vibration intensity effect. Specifically, the core unit of the loofah sponge provides the best isolation effect of axial vibration intensity, with an acceleration vibration transfer of −60 dB at 300 Hz. Furthermore, both the core and shell unit structures combine to provide multidirectional low-frequency vibration isolation. This study of the loofah sponge’s vibration isolation mechanism provides a theoretical foundation and new insights for the design of bionic low-frequency vibration isolation devices.
... working environment is encountered in the ceramics industry, particularly on roof tile production lines, where key machine elements regularly come into direct contact with the processed material, whose main components are clay, quartz sand, and ground crushed brick [6]. The most intensive abrasion occurs in the process of band extrusion, where the production mass is mixed, homogenized, vented, and formed [7]. This process is currently realized in horizontal band plungers, which are made up of a two-shaft mixer and a pug mill [8,9]. ...
... Luffa cylindrica fiber (LCF), like other natural fibers, comprises cellulose (57.51%), hemicellulose (29.47%), lignin (20.45%), and extracts (8.83%) [4]. Numerous researchers have been studying LCF-reinforced polymer composites with the objective of characterizing their properties [5][6][7][8][9]. The effects of alkali treatment on the mechanical properties of an LCF-reinforced epoxy composite were studied by Sathish Kumar et al. [10]. ...
This paper highlights the results of an experimental study on the preparation and characterization of Luffa cylindrica fiber (LCF) and groundnut shell particle (GSP) reinforced phenol-formaldehyde (PF) hybrid composites. The amount of LCFs was fixed at 25 wt%, while the amount of groundnut shell particles ranged from 0 to 25 wt%. Observations were made regarding the water absorption and thickness swelling behaviour of prepared hybrid composites. In addition, the mechanical behaviours of hybrid composites have been studied under both dry and wet conditions. In comparison to dry conditions, the mechanical properties of the hybrid composites were lower when they were wet. Hybrid composites comprising 25% Luffa cylindica fibre and 15% groundnut shell particle (25LCF/15GSP) exhibit the highest level of mechanical properties under both conditions. The percentages of water absorption and thickness swelling increase as groundnut shell particles increase. The composite 25LCF/25GSP exhibited the highest percentage of water absorption and thickness swelling. Compared to date palm leaf (DPL)-reinforced composites, 25LCF/15GSP showed more significant mechanical and physical properties. We concluded that the inclusion of groundnut shell particles in LCF/PF composites substantially improved the mechanical properties of the hybrid composite. The range of increment, however, was narrower under moist conditions compared to dry conditions.
... The characterization of luffa fiber carried out by different methods and the impact of water absorption on the mechanical properties in a maritime environment were established [8]. The first scientific investigation of the luffa sponge's strength, stiffness, and energy absorption properties revealed it to be a viable substitute for sustainable engineering materials in various real-world uses [9]. The relationship between the mechanical and structural properties of luffa cylindrica fiber was established at different levels, from single fiber to a segment. ...
... The percentage error between experimental and regression models is 0-15%, except for LNR 5,8,9,10,12,and LNR26 [41]. This deviation is due to the negative impact of soaking temperature, time, and post-processing parameters in Equation (1). ...
... Nature has the ability to create porous structures to obtain superior acoustic and mechanical properties, such as a high stiffness-to-weight ratio, strong sound absorption/dissipation effect, and high energyabsorbing capability [1]. Common natural porous structures and materials include honeycombs, fibers, and sponges [2][3][4] (Fig. 1 a, c, e). Inspired by these porous structures in nature, a variety of novelty designs have been developed in recent years, including lattice porous structures and foams [5][6][7] (Fig. 1 b, d, f). ...
... Instead, the topology optimization method combined with the mixed u/ p formulation can continuously transform the material properties between the structural and acoustic media [31,32,49] so that there is no need to track their explicit interfaces. Furthermore, topology [2], (b) gyroid cores porous structure [5], (c) multilayer lattice structures in owl wings [1] (d) porous airfoils [3], (e) porous sponges in luffa [4], (f) foam aluminum [7]. optimization of porous structures by simultaneously considering their acoustic and mechanical characteristics is rarely investigated. ...
Porous structures are widely found in nature and have been extensively studied due to their high stiffness-to- weight ratio, excellent sound absorption, and robustness regarding loading variation. This paper proposes a new topology optimization approach for the design of porous acoustic-mechanical structures based on the three- field floating projection topology optimization (FPTO) method. In order to capture the change of ambiguous structural boundary during topology optimization, the mixed displacement/pressure (u/p) finite element formulation with the linear material interpolation scheme is adopted. The artificial porous features of the structures are generated by imposing the local volume constraint defined by a constant or adaptive filter radius. The 0/1 constraints of the design variables are simulated by the floating projection constraint so that the final design has a clear topology. To verify the effectiveness of the proposed method, some interesting 2D and 3D numerical examples considering their mechanical and acoustic characteristics simultaneously are presented to achieve porous structures by minimizing dynamic compliance, possibly with an additional acoustic constraint. The results also show that the resulting porous features are useful in improving the acoustic performance of the optimized designs
... Further they are further classified into periodic and stochastic structures according to the randomness of internal pores [6]. For instance, glass and luffa sponges possess visible open pore structures, while internal microfibers have different structure forms [23,24]. Pomelo peel and cuttlebone have typical multiscale closedcellular foam structures and honeycomb structures, respectively [25,26]. ...
... The structural hierarchy of the luffa sponge includes columns (50 mm), fibers (1 mm), and cellular walls (0.01 mm). Shen et al. [24] investigated the strength and energy absorption properties of luffa sponges. The compressive strength of luffa sponges was about 0.27 MPa, and the corresponding stress-strain curve showed nearly constant plateau stress in the long strain range. ...
The rational design of desirable lightweight structural materials usually needs to meet the strict requirements of mechanical properties. Seeking optimal integration strategies for lightweight structures and high mechanical performance is always of great research significance in the rapidly developing composites field, which also draws significant attention from materials scientists and engineers. However, the intrinsic incompatibility of low mass and high strength is still an open challenge for achieving satisfied engineering composites. Fortunately, creatures in nature tend to possess excellent lightweight properties and mechanical performance to improve their survival ability. Thus, by ingenious structure configuration, lightweight structural biomaterials with simple components can achieve high mechanical performance. This review comprehensively summarizes recent advances in three typical structures in natural biomaterials: cellular structures, fibrous structures, and sandwich structures. For each structure, typical organisms are selected for comparison, and their compositions, structures, and properties are discussed in detail, respectively. In addition, bioinspired design approaches of each structure are briefly introduced. At last, the outlook on the design and fabrication of bioinspired composites is also presented to guide the development of advanced composites in future practical engineering applications.
... The chemical composition of the sponge depends on several factors. These include, among others, the origin of the plant, type of soil, weather conditions for growth, pretreatment, etc. [5]. Luffa cylindrica fibers consist on average of about 65% cellulose, 17% hemicellulose, and 15% lignin [6]. ...
... Life Sci. Forum 2022, 18, 39 2 of 6 more durable, lighter, and partially biodegradable [5,8]. Loofah sponge is a raw material for the production of biofibers and biocomposites, used in the production of packaging, water-absorbing materials, or filters [3,9]. ...
Luffa cylindrica (called loofah sponge) is a plant from the cucurbitaceae family, popular in Asian countries. The fruit of this plant has a specific fibrous structure and after drying it adopts a three-dimensional mesh structure. The aim of this study was to determine the potential ability of the loofah sponge to bind microorganisms on its surface. Research conducted with the participation of Yarrowia lipolytica yeast has shown that loofah sponge has good sorption capacity and can be an excellent biomaterial for binding whole cells of microorganisms. One gram of Luffa cylindrica is able to adsorb about 0.64 g of Yarrowia lipolytica yeast cells, calculated on the basis of dry weight. Binding on the surface of the biopolymer is most effective when the sponge is introduced into the microbial media with the inoculum.
... Luffa presents significant potential for various environmental applications due to its sustainable and biodegradable properties. The increasing interest in luffa for environmental technologies underscores its value as a cost-effective and sustainable solution for pollution mitigation and resource conservation [19,20]. A study showed that when the moisture percentage was minimized to 12.40% in luffa peels, the composition resulted in 38.94% carbohydrate, 14.26% protein, 6.10% fat, 20.60% fiber, and 7.7% ash [21]. ...
The use of low-cost biowaste adsorbents for the removal of toxic metal ions from aqueous solutions offers significant environmental benefits. This research evaluated the adsorption and recovery of Cd2+ and Pb2+ ions in batch and column modes with luffa peels and chamomile flowers. The biosorbents were treated with 0.4 M nitric acid or with 0.4 M NaOH base. An FTIR analysis of the sorbents indicated that surface OH, C=O, CO and COO groups played a role in the adsorption process. L-type isotherms were obtained for Pb2+, fitting both the Langmuir and Freundlich models, with maximum adsorption capacities of 34.0 mg/g for luffa peels and 49.5 mg/g for chamomile flowers. Adsorption isotherms for Cd2+ ion fit better with the Freundlich model with smaller adsorption capacity than Pb2+. Base-treated sorbents have higher adsorption capacity. The adsorption kinetic for both ions are fast and followed a pseudo-second order chemosorption model. Fixed-bed column dynamic adsorption with luffa peels obtained a Thomas dynamic adsorption capacity of 32.9 mg/g for Pb2+ and 25.8 mg/g for Cd2+. The recovery efficiency was 87 to 90% over three adsorption–regeneration cycles.
... Therefore, the nodal bamboo culm has competitive energy absorption performance, which is mainly attributed to the improved anti-split strength and the axial crushing displacement owing to the existence of bamboo nodes. Compared to conventional engineering materials/structures presented in Figure 3(c) [30,[37][38][39], the SEA values of 1-year-old bamboo culms have exceeded most other energy-absorbing materials and structures, especially for nodal bamboo culm with a SEA of 11.8 J/g. Apart from the contribution of bamboo nodes, the gradient distribution of vascular bundles also plays a crucial role in the energy absorption of bamboo structures. ...
The axial collapse mechanical behavior and energy absorption characteristics of circular foam-filled tubes mimicking the bamboo characteristics under quasi-static and low-velocity impact loads were investigated via experiments and numerical simulations in this study. The crushing deformation process, load-displacement responses, the strain field and temperature field distribution characteristics of foam-filled tubes were explored. The energy absorption mechanism and crashworthiness performance of specimens were evaluated and compared with conventional empty tubes. Effects of ambient temperature on axial collapse behavior and crashworthiness indices were also clarified. The results revealed that the superior energy absorption capacity of foam-filled tubes was attributed to the strengthening effect of bionic joints and the filling effect of aluminium foam. The energy absorption ( EA ), specific energy absorption ( SEA ), and other crashworthiness indices of foam-filled tubes under axial impact load were greatly improved than that of quasi-static load. Compared to conventional empty tubes, the foam-filled tube had a larger energy-absorbing effectiveness factor under both quasi-static and dynamic loads. The increased temperature weakens the crashworthiness performance and energy absorption ability of the foam-filled tube. The SEA values ranged from 28.2 J/g to 22.1 J/g for the quasi-static load and 31.9 J/g to 26.3 J/g for the dynamic load when the temperature elevated from −50 ℃ to 100 ℃.
... [14,15]. Loofah materials offer strong adsorption, breathability, antibacterial qualities, sweat resistance, and tensile strength [16]. ...
This study is based on environmental sustainability and aims to explore the preparation and evaluation of biodegradable bio-fibre materials using discarded bougainvillaea, loofah, and aloe. After sorting and analyzing the existing literature, it is found that research on bougainvillaea, loofah, and aloe primarily focuses on environmental science, horticulture, biology, light industry, and pharmacy, while research on bio-fabric combining bougainvillaea, loofah, and aloe in two or three combinations remains unexamined. This study adopts both observational and experimental methods to identify candidate varieties suitable for natural dyeing by observing the characteristics of bougainvillaea and by preparing and testing bio-fibre materials through experimentation. Notably, the beet pigment found in bougainvillaea serves as a natural dye, the α-cellulose and hemicellulose in loofah sponge provide strong hydrophilicity, and the caffeic acid and rhamnolipids in aloe exhibit antioxidant and antibacterial properties, thereby improving the fabric’s safety. Experimental results and final bio fibre performance tests indicate that fibres made from these three plants have a stable internal structure, abrasion resistance of over 30,000 cycles, colour fastness concentrated at level 4, and a contact angle of less than 90°, thereby showing good stability, abrasion resistance, colour fastness, and hydrophilicity. Consequently, this study finds that bio-fibres prepared from bougainvillaea, loofah, and aloe demonstrate promising performance and are expected to contribute to the development of sustainable fibres in the future.
... The strongest fiber is in the central region and arranged in the radial direction. In the middle layer the fibers grow in three directions (Shen et al. 2012). ...
Water contamination over the years due to hazardous organic and inorganic pollutants poses an immediate threat to both the environment and human health. Extensive research has been conducted on the application of the adsorption technique to treat these effluents. With a focus on adhering to the principles of Green Chemistry and the circular economy, researchers are directing their efforts toward discovering economical, biodegradable, and readily available adsorbents. In this context, the present review article offers insights into recent studies regarding the utilization of the natural biosorbent Luffa cylindrica. This porous, environmentally friendly, and non-toxic material shows promise in the realm of wastewater treatment. Emphasis was also given to several fiber modifications aimed at enhancing the adsorption capacity of this biosorbent. Additionally, comprehensive physicochemical characterizations were conducted, including SEM, TEM, FTIR, XRD, N2 adsorption and desorption and contact angle analyses. The impact of adsorption parameters was discussed in detail. The review delves into kinetic, equilibrium, and thermodynamic data, which have been presented and analyzed. Mechanistic insights into the adsorption interactions between the adsorbent and adsorbate are depicted through illustrative diagrams. Ultimately, the findings underscore the potential of both Luffa and Luffa-based materials as promising candidates for effective wastewater treatment applications.
... The chemical composition of loofah primarily comprises lignin and hemicellulose/cellulose, along with various inorganic elements such as glycosides, polypeptides, amino acids, proteins, and more [27][28][29]. The hemicellulose content varies from 8% to 22%, while the lignin content ranges from 10% to 23%. ...
Using Egyptian (EAGLE) unsaturated polyester resin and methyl ethyl ketone peroxide catalyst, natural Egyptian sponge loofah (NELS) fibers were created as composite materials for this investigation. Handmade moulds were created for research trials. Separate additions of the fillers were made in various ratios (5, 10, 20, 30, 40, and 50% vol.). The results indicate that adding (NESL) fiber increases the material's hardness and compressive strength. At 50% vol. and 40% vol. (NESL) fiber, (71.84 Hv, 62.60 MPa) respectively, the maximum hardness and compressive strength were reached. Furthermore, it was discovered that increasing the amount of (NESL) fiber from 5% vol. to 50% vol. resulted in a very slight drop in density for the final (NESL) composite under investigation. The present study highlights the feasibility of using Natural Egyptian Sponge Loofah fiber composites as a reinforcing agent in Egyptian unsaturated (EAGLE) polyester. This approach provides a balance between increased mechanical strength and improved mechanical stability, hence expanding the applicability of these composites in engineering domains.
... As shown in Fig. 8(a), to verify the accuracy of the VSF design of variable stiffness structures, energy efficiency curves were calculated according to the stress-strain curves of the three specimens. Energy efficiency is a key index that determines the initial dense strain, peak stress and specific energy absorption of porous materials [56,57]. The formula for calculating energy efficiency is defined as: ...
... Fibers derived from renewable sources possess remarkable characteristics, such as low cost, low density, and biodegradability, which make them candidates for improving composite materials' mechanical features and sustainability. Among the natural fibers explored, Luffa cylindrica, commonly known as sponge gourd or luffa, has emerged as a compelling option due to its properties, including high aspect ratio, good tensile strength, and abundant availability (Bal, 2004;Shen, 2012;Joshi, 2004) Optimizing Flexural Strength in Polyester/Luffa Fiber Composites via Gamma Radiation Treatment Optimización de la fuerza en flexión en compuestos de resina poliéster /fibras de luffa, mediante tratamiento de radiación gamma ...
This investigation aims to assess the flexural properties of polyester resin/luffa fibers composites. Three different kinds of specimens were tested; the first one consisted of polyester resin exposed to gamma rays at doses ranging from 0 to 500 kGy. The second were composites produced with polyester resin and 1-5 wt% luffa fibers, and the last one consisted of polyester resin and 5% luffa fibers composites exposed to gamma rays (100, 200, 400 and 500 kGy doses). The results show a maximum increase of 27% in flexural modulus when polyester resin was irradiated at a 500 kGy dose. However, there was a decrease of 72% in deformation when 5% of luffa fibers were added. This indicates an increase in rigidity in all three types of specimens but an adverse effect on the strain at rupture. Therefore, the combination of adding luffa fibers and exposing the composites to gamma rays appears to be a suitable method for improving rigidity, albeit with some limitations in deformation.
... It is frequently disposed of as agricultural waste in that area. Its fruit contains a vascular system that looks like a net and is made up of 55-90% cellulose, 8-22% hemicellulose, 10-23% lignin, and 3-6% extractive ash (Shen et al. 2012). LC fibers have excellent mechanical properties such as specific strength and elasticity module, in addition to remarkable stiffness and the capacity to absorb energy (Mazali and Alves 2005;Shen et al. 2013). ...
The growing prevalence of polymer-based plastics in the environment is an imminent risk to the natural world. As an immediate consequence of this, extensive research has been launched over the course of the past few decades in an effort to reduce the damage that manmade plastics cause to the natural environment. The current study attempts to explore the biodegradability of polylactic acid (PLA), a bio-compatible plastic, by incorporating small amount of electron beam irradiated natural fibers (2 to 10%) derived from luffa cylindrica (LC) at varying irradiation doses (0.5 Gy, 1 Gy, and 2 Gy). Natural fiber surface treatment using electron beam irradiation is effective and environmentally friendly. The biodegradation of composites was studied for 90 days in sand, soil, compost, brackish water, fresh water, salt water, and bacterial and fungal conditions. Maximum decomposition was observed in the composite sample (PLA/10% wt of LC fiber at 2.0 Gy) at 15.42% and 4.73% in bacterial and soil environments. X-ray diffraction (XRD) and Raman spectroscopy validated the fiber and PLAs crystallinity and molecular interaction. The derivative thermo-gravimetric curve (DTGA) showed that electron beam irradiation removed moisture, hemicelluloses, and lignin from hydrophilic fibers. The incorporation of LC fibers into the bio-composites resulted in an increase in the glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc). Additionally, after LC fiber reinforcement, the composites’ dielectric properties were enhanced.
Graphical Abstract
... Luffa is a natural woven fibre with a net-like fibrous vascular system. When they are treated and dried, the fibrous network structure becomes readily open like cell foam material (Shen et al., 2012). This makes the stress-strain relationship to be linear in the elastic region as observed in Figure 2. The maximum load for treatments 1, 2, 3 and 4, in the elastic regime, are 80. ...
Treatment of natural fibers is an important way of improving their properties for specific applications. Luffa cylindrica is an excellent low-cost fiber for reinforced composite applications. The aim of this study was to investigate the influence of mercerisation, acetylation and oxidation pre-treatment on the tensile properties of Luffa fibres. It was observed that the stress-strain relationship for Luffa fiber is linear in the elastic region, with the untreated fiber withstanding the highest value of force in this phase. This proportional relationship was also consistently observed at the elastic region for all treatment types employed. The tensile strength of the untreated fibers was 7.083 MPa. There was an improvement in the tensile strength with acetylation (7.541 MPa) and a reduction due to oxidation (5.11 MPa) and mercerisation (5.517 MPa). We observed that the stress and strain within and outside the elastic region differed across treatment types and elastic regimes. Therefore, the study highlights the importance of considering the specific application when selecting the appropriate Luffa fibre treatment method.
... And, the bioinspired structure shows a 29% reduction in the peak load and a 69% increase in energy absorption [23]. Furthermore, other types of structures in nature have also been used by many scholars for the development and application of lattice structures, such as pemelo peel [24], horse hoof [25], luffa-sponge-like hierarchical cellular structures [26][27][28], and bio-inspired Kagome truss [29]. As a result of the mechanical characteristics, biological structures always present inspiration for the development of high-performance mechanical structures [30]. ...
This paper aims to explore the influence of surface curvature distribution on the mechanical properties of lattice structures. In this study, a series of typical structure types were designed to obtain lattice structures with different surface Gaussian curvatures, including BCC (body center cubic) configuration, cross-cube configuration, and diamond lattice structure. Then, the above-mentioned porous structural sample was formed by SLM (selective laser melting), and the relevant mechanical properties were obtained by simulation and experiment. In addition, a characteristic method to describe the surface curvature of discrete triangular plaques is proposed and used to calculate the curvature distribution of the designed lattice structure. The results show that the lattice structure with concentrated Gaussian curvature distribution on the surface has good mechanical properties. Especially, for the cross-cube structure, the elastic modulus of the traditional configuration lattice structure increases by 79%, and the elastic modulus of the stretched structure increases by 70% when the volume fraction increased from 10 to 15%. Meanwhile, the elastic modulus for the traditional structure and the stretched structure increases by 41% and 14%, respectively, when the volume fraction of the structure increases from 15 to 20%. It is noted that the influence of surface curvature distribution on mechanical properties is slightly inferior to the volume fraction, which provides a new idea for the quantitative evaluation and design of porous structural properties. In addition, the BCC structure with concentrated curvature distribution provides a new scheme for the protection device after the stress climb stage after the elastic stage. Furthermore, the influence of surface curvature on the mechanical properties of lattice structures described in this paper will provide new inspiration for lattice structures in the fields of biocompatibility and heat exchange.
... Luffa chemical constitution mostly involves of lignin and cellulose/hemicellulose, in addition to includes a few inorganic elements similar proteins amino acids, and glycosides so on [20][21][22]. Sodium hydroxide (NaOH)/alkaline treatment has proven its potential to enhance the microstructure of luffa fibers by changing their chemical composition and expelling all contaminants [23][24][25][26]. Morinda tinctoria is also one more plant material utilized for this research; it also is locally identified as "Togaru" and is also well known in Asia as Indian mulberry, aal, together with nunaa. ...
As the name implies, natural fiber composites (NFC) are made of natural resources and thus have environmentally beneficial properties such as biodegradability. NFC has gained popularity in recent years due to its natural characteristics in a variety of applications such as automotive, goods, structural, and infrastructure. The objective of this study is to enhance the static, dynamic mechanical and thermal stability of new fibers/biodegradable hybrid composites. This paper focuses for the first time on three new and distinct types of fiber and fillers such as luffa, Morinda tinctoria wood powder, and myrobalan seed powder. In this work, due to good attributes of luffa fiber, it was maintained constant weight percentage (wt%). Morinda tinctoria wood powder and myrobalan seed powder were used on various wt%. compositions. The alkali-treated fiber-reinforced epoxy composite samples were fabricated through the hand lay-up method. Tensile and flexural characteristics of luffa/epoxy (LMM5) composite was attained as 287.14 MPa and 378 MPa, respectively. Addition of more than 45% of myrobalan seed powder reveals negative effect on both ductile and flexural characteristics. Furthermore, in dynamic mechanical analysis, the incorporation of 45 wt% myrobalan seed powder changed the glass-transition temperature and rubbery stage. These composite materials have such a wide range of applications, including vibration sound absorption, isolation, packaging, structural, and so on.
... The fiber derived from mature and dry fruits has various uses and predominantly used as bathroom and kitchen sponges, washing and cleaning materials and sound proofing materials [59]. Whereas loofah fiber's mechanical properties, and information related its composites can be found in [60] and [61,62], respectively. ...
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... The fiber derived from mature and dry fruits has various uses and predominantly used as bathroom and kitchen sponges, washing and cleaning materials and sound proofing materials [59]. Whereas loofah fiber's mechanical properties, and information related its composites can be found in [60] and [61,62], respectively. ...
... In this work, a novel explicit multiscale topology optimisation method based on the discrete geometric component-based approach is proposed to design bio-mimicking structures. The closed-form foamy feature, which is commonly existed in biological materials such as turtle shell (carapace) (Achrai and Wagner 2017), pomelo peel (Thielen et al. 2013), porcupine quill (Yang and McKittrick 2013) and luffa sponge (Shen et al. 2012) to maintain strong without losing high stiffness, is regarded as the target of bio-mimicking. A novel path to the design of advanced customised products with more freedom and ability of bio-mimicking can be built up. ...
This paper presents a novel multiscale explicit topology optimisation approach for concurrently optimizing the structure at the macro level and the bio-mimicking porous infillings at the micro level. Solid bar components with cross-section control at the macro level and sphere components at the micro level are constructed as the minimal control units to replace the manipulation of material distribution at each grid. The overlapping, moving and morphing of bar components provide the ability to generate flexible structural shapes at the macro level. Using the inspiration of the turtle shell (carapace), the sphere components are designed to move, overlap, and resize inside the bar to sufficiently mimic both the regular and irregular porous features. Classical beam designs, lattice structure designs and unit cell designs are illustrated as numerical examples to demonstrate the functionalities and correctness of the proposed method. As a result, the stochastic pores distribution and porosity control can be validated. The abilities of optimising lattice structure at truss-level and single unit cell level are demonstrated. Moreover, the samples are fabricated by selective laser melting (SLM) technology and then scanned with the X-ray micro-computed tomography (micro-CT) technique to further examine the manufacturability.
... Additionally, luffa sponges can be found for a reasonable price in China, Japan, and other nations in Asia and South America. Due to its excellent mechanical qualities, renewable structure, high water sorption capacity, stable structure, and degradability, this sponge has many uses in daily life [35][36][37][38] see Fig. 1. Hydrophobic bio-waxes, like Carnauba wax (CW) and rice bran wax, can become entirely non-toxic right away after being dissolved in polar solvents. ...
Water pollution by hydrocarbon derivatives is one of the significant problems and challenges globally and is one of the leading causes of disease and environmental catastrophes. Increasing oil effluents have become a primary global concern due to damage to living ecosystems and marine life. This oil should be removed from the water or the surface to protect the water and the environment. One of the most important remedies for oil spills is using sorbent materials. Conventional synthetic sorbents for oily water treatment are the most broadly applied materials, although they are not the optimal selection from environmental and economic points of view. However, the utilization of biobased sorbents derived from natural materials with environmentally friendly, low-cost, reusability, abundant, and biodegradability properties can be an ideal alternative for convectional synthetic sorbent, with a positive effect on sustainability and circular economy. These types of sorbents are used with various sizing from micro to nanoscale in different forms (membrane, aerogel, foam, and sponge). The objective of this paper is to review a report on the use of porous biobased sorbents in both natural and modified forms which are available in nature or our lives. Modification strategies for improving hydrophobicity of biobased sorbent were also broadly highlighted. Finally, the challenges and future research directions of this promising research field are briefly discussed.
This paper develops low-cost, high-performance impact-resistant materials using natural luffa sponge as reinforcement for cementitious composites. It is the first to investigate the effect of temperature on the impact performance of luffa sponge-reinforced cementitious composites (LSRCC) across a wide range from − 196°C to 200°C. Addressing the brittleness of traditional materials at low temperatures, this study pioneers a sustainable, ultra-low-temperature impact-resistant material. Experimental results indicate a strong synergy between the luffa sponge and cement matrix, with the sponge’s networked fibers significantly enhancing structural integrity. Remarkably, LSRCC maintains cohesion under repeated impacts with minimal disintegration. It also exhibits low temperature sensitivity and excellent impact resistance in extreme environments. Interface properties between the luffa sponge and cement matrix were characterized using Focused Ion Beam (FIB) and Transmission Electron Microscopy (TEM), supported by Density Functional Theory (DFT) simulations. Results confirm a gradual Interfacial Transition Zone (ITZ) rather than a simple mechanical bond. Simulations reveal that hydrogen bonding within the cellulose matrix drives a gradual variation in the water-to-cement ratio across the interface, resulting in a progressive transition in interfacial strength. This transitional region enhances the load-bearing capacity of LSRCC, highlighting its superior synergistic behavior.
Compared to single-decker ball bearings, double-decker ball bearings offer advantages such as higher speed limits, greater load capacity, and better impact performance. However, the inclusion of an additional bearing and adapter ring structure increases its overall mass, limiting its applications. This study addresses the challenges of achieving lightweight design and impact resistance in double-decker ball bearings. Using bionic principles, this study analyzes the internal spatial structure and fiber distribution of loofah to guide the bionic design of the adapter ring in the double-decker ball bearing. A new bearing structure inspired by loofah characteristics is proposed, and a finite element model for its mechanical analysis is developed. The structural response of both the new and traditional double-decker ball bearings is analyzed under varying speeds and impact excitation conditions. The results indicate that the mass of the new adapter ring is reduced by 25.26%, with smaller stress variation and more uniform stress distribution in the bionic design. The overall performance of the new double-decker ball bearing outperforms the traditional design in terms of deformation, equivalent stress, equivalent strain, and contact stress. The proposed bionic loofah-inspired double-decker ball bearing meets both lightweight and impact resistance requirements. The findings provide a theoretical foundation for applying double-decker ball bearings in high-impact and lightweight applications.
As an important class of auxetic metamaterial, the re-entrant honeycomb has received much attention due to its
excellent energy absorption. However, re-entrant honeycombs are prone to instability under compression and its
lateral stiffness is considerably low. In order to tackle these issues, novel auxetic hybrid structures are proposed
by combining re-entrant cells and face-centered cubic (FCC) cells. The mechanical properties of re-entrant
honeycombs with FCC cells under lateral and axial loads are analyzed numerically and experimentally. Due to
the high stiffness of FCC cells, the cells can be used as the reinforcement inside the hybrid structure to stabilize
the deformation. The results show that re-entrant honeycomb with FCC cells shaped X (RHFX) and FCC cells
shaped diamond (RHFD) exhibit more stable deformation modes and better energy absorption characteristics
compared with traditional honeycombs under axial and lateral loads. The effects of geometric dimensions on the
energy absorption performance of the two structures was investigated by numerical method. Due to their
excellent mechanical properties, the RHFX and RHFD have great potential to protect the vehicles and
infrastructures.
Domestic laundry wastewater is a major contributor to microfiber emissions in the aquatic environment. Among several mitigation measures, the use of external filters to capture microfibers from wastewater is one of the most efficient and commercially viable methods. This study attempted to develop an eco-friendly filtration medium to filter microfibers in laundry wastewater using luffa cylindrica fibers. Sourced luffa fibers were made into tight rolls and stacked in a filtration column to filter the effluent. The analysis showed that the alkali-treated luffa fiber rolls were more effective in filtering the microfibers than untreated luffa fibers. Hence, the alkali treatment process was optimized for better performance; an alkali concentration of 5.8%, treatment time of 5 h, and 37 °C temperature provide better performance. The characterization of alkali-treated luffa fibers showed significant changes in the morphology and removal of lignin and hemicellulose components, enhancing the physical adsorption of microfibers on the surface. The experimental filtration results showed that the developed filter can effectively remove up to 93% of microfibers from laundry effluent, and the efficiency remained superior for up to 15 filtrations. Furthermore, an increase in filtration leads to the accumulation of detergents in the luffa net-like vascular structure and reduced effectiveness. The use of the developed product in a real-time washing machine outlet was found to be effective with an efficiency of 98%. The developed product is a versatile and cost-effective solution, suitable for use in domestic washing machines. Its simplicity and ease of integration make it an effective and eco-friendly alternative for filtering microfibers from laundry effluent. The future direction of the study also suggests a sustainable disposal method for luffa fibers using it as a matrix material in red soil-based thermal or sound insulation panels and restricting the reach of microfibers into the environment.
Wheels have been commonly used for locomotion in mobile robots and transportation systems because of their simple structure and energy efficiency. However, the performance of wheels in overcoming obstacles is limited compared with their advantages in driving on normal flat ground. Here, we present a variable-stiffness wheel inspired by the surface tension of a liquid droplet. In a liquid droplet, as the cohesive force of the outermost liquid molecules increases, the net force pulling the liquid molecules inward also increases. This leads to high surface tension, resulting in the liquid droplet reverting to a circular shape from its distorted shape induced by gravitational forces. Similarly, the shape and stiffness of a wheel were controlled by changing the traction force at the outermost smart chain block. As the tension of the wire spokes connected to each chain block increased, the wheel characteristics reflected those of a general circular-rigid wheel, which has an advantage in high-speed locomotion on normal flat ground. Conversely, the modulus of the wheel decreased as the tension of the wire spoke decreased, and the wheel was easily deformed according to the shape of obstacles. This makes the wheel suitable for overcoming obstacles without requiring complex control or sensing systems. On the basis of this mechanism, a wheel was applied to a two-wheeled wheelchair system weighing 120 kilograms, and the state transition between a circular high-modulus state and a deformable low-modulus state was realized in real time when the wheelchair was driven in an outdoor environment.
Background
This study explored the utilization of luffa sponge (LS) in enhancing acetification processes. LS is known for having high porosity and specific surface area, and can provide a novel means of supporting the growth of acetic acid bacteria (AAB) to improve biomass yield and acetification rate, and thereby promote more efficient and sustainable vinegar production. Moreover, the promising potential of LS and luffa sponge coated with κ-carrageenan (LSK) means they may represent effective alternatives for the co-production of industrially valuable bioproducts, for example bacterial cellulose (BC) and acetic acid.
Methods
LS and LSK were employed as adsorbents for Acetobacter pasteurianus UMCC 2951 in a submerged semi-continuous acetification process. Experiments were conducted under reciprocal shaking at 1 Hz and a temperature of 32 °C. The performance of the two systems (LS-AAB and LSK-AAB respectively) was evaluated based on cell dry weight (CDW), acetification rate, and BC biofilm formation.
Results
The use of LS significantly increased the biomass yield during acetification, achieving a CDW of 3.34 mg/L versus the 0.91 mg/L obtained with planktonic cells. Coating LS with κ-carrageenan further enhanced yield, with a CDW of 4.45 mg/L. Acetification rates were also higher in the LSK-AAB system, reaching 3.33 ± 0.05 g/L d as opposed to 2.45 ± 0.05 g/L d for LS-AAB and 1.13 ± 0.05 g/L d for planktonic cells. Additionally, BC biofilm formation during the second operational cycle was more pronounced in the LSK-AAB system (37.0 ± 3.0 mg/L, as opposed to 25.0 ± 2.0 mg/L in LS-AAB).
Conclusions
This study demonstrates that LS significantly improves the efficiency of the acetification process, particularly when enhanced with κ-carrageenan. The increased biomass yield, accelerated acetification, and enhanced BC biofilm formation highlight the potential of the LS-AAB system, and especially the LSK-AAB variant, in sustainable and effective vinegar production. These systems offer a promising approach for small-scale, semi-continuous acetification processes that aligns with eco-friendly practices and caters to specialized market needs. Finally, this innovative method facilitates the dual production of acetic acid and bacterial cellulose, with potential applications in biotechnological fields.
To unleash the emotional potential of natural fibre materials in sustainable development and utilisation, this paper presents a material-driven design method with emotional and ecological indicators (E²-MDD). The method offers product-level solutions for the sustainable development of natural materials. The method involves several steps, such as screening the main material quality, capturing the user emotion vision, deconstructing the E² vision pattern, and deducting the product design concept. The method was tested on luffa sponge samples, seen as one kind of traditional fibre resource, which resulted in four differentiated schemes, which were evaluated using the E²-MDD ring radar column score chart. The study identified three key emotional qualities for natural fibre materials: associativity, uniqueness, and biophilicity. The results show that product concepts closer to the natural material’s original form scored higher, while the inclusion of non-natural materials had a negative impact on the evaluations. This study also found that E²-MDD could strengthen the emotional and ecological connection between people and products, further indicating that material and design can establish a link between environmental friendliness and emotional experience. Lastly, the paper suggests future development areas for the E²-MDD method, including focusing on users, ecology, and business.
A detailed acquisition, analysis, and representation of biological systems exhibiting different functions is required to develop unique bio-inspired multifunctional conceptual designs and methods. This paper presents BIKAS: Bio-inspired Knowledge Acquisition and Simulacrum, a knowledge database of biological systems exhibiting various functionalities, developed based on case-based bio-inspired examples from literature. The knowledge database represents the biological features, their characteristics, and the function exhibited by the biological feature as a combination of its integrated structure and structural strategy. Furthermore, this knowledge database is utilized by the Expandable Domain Integrated Design (xDID) model that works on classifying, mapping, and representing biological features into their respective geometric designations called Domains. The combination of features from the Domains results in the generation of multifunctional conceptual designs. In addition, Meta-level design factors are proposed to aid designers in filtering the biological features and their respective functions having a similar structural strategy, thus aiding designers in rapidly selecting and emulating biological functions.
The remediation of heavy crude oil spills is a global challenge because frequent crude oil spills cause long-term damage to local living beings and marine ecosystems. Herein, a solar-driven and Joule-driven self-heated aerogel were developed as an all-weather adsorbent to efficiently absorb crude oil by obviously decreasing the viscosity of crude oil. The cellulose nanofiber (CNF)/MXene/luffa (CML) aerogel was fabricated via a simple freeze-drying method using CNF, MXene, and luffa as raw materials, and then coated with a layer of polydimethylsiloxane (PDMS) to make it hydrophobic and further increase oil-water selectivity. The aerogel can quickly reach 98 °C under 1 sun (1.0 kW/m2), which remains saturated temperature after 5 times photothermal heating/cooling cycles, indicating that the aerogel has great photothermal conversation capability and stability. Meanwhile, the aerogel can also rapidly rise to 110.8 °C with a voltage of 12 V. More importantly, the aerogel achieved the highest temperature of 87.2 °C under outdoor natural sunlight, providing a possibility for promising applications in practical situations. The remarkable heating capability enables the aerogel to decrease the viscosity of crude oil substantially and increase the absorption rate of crude oil by the physical capillary action. The proposed all-weather aerogel design provides a sustainable and promising solution for cleaning up crude oil spills.
Interfacial solar steam generation (ISSG) is considered to be an attractive technique to address the water shortage. However, developing a sustainable thermal management, salt rejection, and excellent mechanical strength ISSG device for long-term stability desalination is still a challenge. Herein, a biomass ISSG device with superb mechanical properties was prepared by introducing a luffa sponge as the skeleton and constructing the MXene/cellulose nanofibers (CNFs) aerogels via freeze-drying. The Janus MXene-decorated CNFs/luffa (JMCL) aerogels integrated the multifunction of fast water transport, good thermal management, and efficient photothermal conversion in a single module, to achieve high-efficiency desalination. 3D Janus structure endowed the JMCL aerogel with opposite wettability, which is feasible to construct the localized photothermal generation and self-floating. The mechanical strength of JMCL aerogels is 437 times that of MXene/CNFs aerogels. The JMCL aerogels delivered a water evaporation rate of 1.40 kg m-2h-1 and an efficiency of 91.20% under 1 sun illumination. The excellent salt resistance during 24 h working and long-term solar vapor generation of up to 28 days were achieved. The multifunctional JMCL aerogels with 3D Janus structure offer new insights for developing good durability and eco-friendly biopolymer-based steam generators.
Lithium-ion sieve (H1.6Mn1.6O4) with porous nanofiber structure imitating loofah skeleton was prepared by electrospinning and high-temperature calcination in this paper. The NFs@LIS-6:6 obtained a controllable porous nanofiber structure and abundant...
The mathematical models for predicting the sound absorption coefficients (SACs) of porous samples are first presented, then they are used to predict the SACs of some porous structures, and their performances are evaluated. First of all, the parameters needed for the calculation of the SACs of a porous sample are briefly introduced. After that, the mathematical models for the prediction of acoustic properties are presented. These models include (i) simple empirical models such as Delany-Bazley and its modified versions, (ii) rigid-frame models such as Johnson-Champoux-Allard and Johnson-Champoux-Allard-Lafarge, and (iii) deformable-frame models such as Biot-Allard. After that, the estimation of the parameters needed in the mathematical models is presented. Then, the aforementioned models are used to predict the SACs of some porous samples including cellulose fiber-based structures, and their performances are evaluated in detail.
Nature is a continuous source of inspiration for scientists and engineers for creating innovative products. In the past decade, many methods, frameworks, and tools have been developed to support the design and development of biologically inspired products. This research provides an overview of the current state-of-the-art bio-inspired design methods and identifies that there is a need for the development of methods to support multifunctionality in design. Although there are several methods that assist in the development of multifunctional designs inspired by biology, there is still a gap identified in the emulation and integration of biological features to achieve multifunctional bio-inspired designs. This paper presents a comparative analysis of the current methods for multifunctional bio-inspired design based on nine specific criteria and, in the end, introduces a new design method called Domain Integrated Design (DID) that will further aid in the generation of multifunctional design concepts inspired from biology.
Tensile and impact properties of compression molded unsaturated polyester/jute composites were investigated as a function of fiber content and orientation. Both unidirectional fiber composites with 0-50% weight fiber content and a randomly distributed short-fiber composite with 30% w/w were manufactured. The unidirectional composites were tested along and transversally to the fiber axis. Higher values for all mechanical properties were obtained when long-fiber oriented composites were tested along the fiber axis, even at low fiber content (10% w/w). The tensile behavior of the unidirectional composites qualitatively followed the theoretical isostrain and isostress behaviors, when the tests were conducted along and perpendicular to the fiber axis, respectively. The tensile properties of the composites tested perpendicular to the fiber were dominated by the strain at the fiber-matrix interface. Properties for randomly distributed short-fiber composites were found to be intermediate between those obtained with long-fiber oriented composites with the same fiber load tested along and across the fiber direction.
The accumulation of toxic industrial waste has become for man and his environment, a topical problem. Organic products come in a large share of this pollution, and their elimination is the subject of much research. It exists in the literature of many studies on plant fibers, but very few are devoted to the study of fibers of the luffa Cvlindrica, hence the idea of directing a study in this direction. Indeed, Luffa cylindrica is an annual herb of the family Cucurbitaceae fruit gives slightly angular cylindrical shape of variable size. In the first step, we studied the kinetics of adsorption system (copper/fiber of Luffa cylindrica) using copper pollution model and method of analysis as UV spectrophotometry, the estimation of specific surface area (0.082 m2/g) revealed a porous biomaterial too, although its maximum adsorption capacity (0.101mg/g) under optimal conditions is low. In the second step two comparative models (Langmuir and Freundlich) were tested for the adsorption isotherms obtained. We completed this work by studying the possibility of regeneration (30.2%) and reuse this material. For that several parameters were optimized: the nature of the desorbent, the pHi 1.5, and the content of Luffa cylindrica desorbing, hence the method and very promising for the treatment of water laden with heavy metals. It allows them to concentrate and recover in a smaller volume, making the process more economical.
Recently, the use of lignocellulosic fibres to reinforcing composite has received an increased attention. However, lack of good interfacial adhesion makes important the treatment of raw materials. Chemical treatment prepared the raw material to be useful by elimination of gummy and waxy substances. In this study, the Luffa fibres were treated by tow methods: alkali treatment and mixed treatment (sodium hydroxide and hydrogen peroxide). The effect of these treatments on the structure of fibres was showed using SEM and XRD (X-Ray Diffraction) analysis. The SEM results revealed that both treatments resulted in a removal of lignin, pectin and hemicellulose substances, and change the characteristics of the surface topography. The XRD analysis shows the increase of crystallinity index by many treatment conditions. We find that the alkali treatment (120 °C; 3 h; 4% NaOH) shows a good cleaning and the higher crystallinity index of treated fibres. It is also interesting to note that mixed treatment can change the Luffa fibres from mat structure to fibrils structure.
Sponge-gourds, the fruit of Luffa cylindrica, are widely used throughout the world. It is an annual climbing crop which produces fruit containing fibrous vascular system. It is a summer season vegetable. At the moment, from the results of studies carried out on this wonder crop, it encourages the commercial cultivation of the crop because of its increasing economic importance. The objective of this review is to show the potentialities of this crop that is virtually found around the globe. Areas such as agriculture, medicine, science, engineering and biotechnology will be discussed. Recent major advances and discoveries will be considered.
Porous materials are commonly found in nature and as industrial materials such as wood, carbon, foams, ceramics and bricks. In order to use them effectively, their mechanical properties must be understood in relation to their micro-structures. This paper studies the mechanical properties of a few common porous materials: carbon rods, ceramics, polymeric foams and bricks. The characterisation of pore structures was performed using a Mercury Porosimeter. Detailed information was obtained on the density, porosity, surface area and pore size distribution. A large number of experiments on either bending or compression were conducted in order to obtain their macro-mechanical properties such as Young''s modulus, hardness and strength. Based on the experimental observations, theoretical models were employed to predict the macro-properties from the micromechanics viewpoint. By studying the deformation of pores the global behaviour was calculated. Two simple formulae for the elastic modulus, E, were proposed: for low values of porosity, , E = E0(1 – 2) (1 + 42) where E0 is the elastic modulus when the porosity is zero; for high value of porosity such as for foams E = E0 (1 – )2. The theoretical results agreed well with the experimental ones. The study has provided insights into the mechanical properties of porous materials over a wide range of porosity values.
The evolution of plastic deformation in a cellular Al alloy upon axial compression is monitored through a digital image correlation procedure. Three stages in the deformation response have been identified. The first involves localized plastic straining at cell nodes. It occurs uniformly and leads to a nominal loading modulus appreciably lower than the stiffness. The second comprises discrete bands of concentrated strain containing cell membranes that experience plastic buckling, elastically constrained by surrounding cells. In this phase, as the loading increases, previously formed bands harden, giving rise to new bands in neighboring regions. The localized bands exhibit a long-range correlation with neighboring bands separated by 3–4 cells along the loading direction. This length scale characterizes the continuum limit. Thirdly, coincident with a stress peak, σo, one of the bands exhibits complete plastic collapse. As the strain increases, this process repeats, subject to small stress oscillations around σo.
The effects of coupling agents on the mechanical, morphological, and water sorption properties of luffa fiber (LF)/polypropylene(PP) composites were studied. In order to enhance the interfacial interactions between the PP matrix and the luffa fiber, three different types of coupling agents, (3-aminopropyl)-triethoxysilane (AS), 3-(trimethoxysilyl)-1-propanethiol (MS), and maleic anhydride grafted polypropylene (MAPP) were used. The PP composites containing 2–15 wt% of LF were prepared in a torque rheometer. The tensile properties of the untreated and treated composites were determined as a function of filler loading. Tensile strength and Young's modulus increased with employment of the coupling agents accompanied by a decrease in water absorption with treatment due to the better adhesion between the fiber and the matrix. The maximum improvement in the mechanical properties was obtained for the MS treated LF composites. The interfacial interactions improved the filler compatibility, mechanical properties, and water resistance of composites. The improvement in the interfacial interaction was also confirmed by the Pukanszky model. Good agreement was obtained between experimental data and the model prediction. Morphological studies demonstrated that better adhesion between the fiber and the matrix was achieved especially for the MS and AS treated LF composites. Atomic force microscope (AFM) studies also showed that the surface roughness of LFs decreased with the employment of silane-coupling agents.
Thin and thick panels of two types of aluminium closed-cell foams of ∼0.20–0.31 g/cm3 (ALPORAS) and ∼0.32–0.57 g/cm3 (ALULIGHT) density were tested in uniaxial compression and the mechanical properties of the panels, plastic collapse strength, plateau stress and absorbed energy, were extracted. Their dependence on the foam density and specimen thickness was also ascertained. Micro-indentation tests were used to estimate the yield stresses of the parent materials. It was found that the higher density panels of ALULIGHT were also more anisotropic than the lower density panels of ALPORAS, and the collapse strength and the absorbed energy of both foams increased with density. More significant scatter the results was observed in the thin and higher density panels.
Biomorphic self-supporting MFI-type zeolite frameworks with hierarchical porosity and complex architecture were prepared using a 2-step (in-situ seeding and secondary crystal growth) hydrothermal synthesis in the presence of a biological template (Luffa sponge), employed as a macroscale sacrificial structure builder. The bio-inspired zeolitic replica inherited the complex spongy morphology and the intricate open-porous architecture of the biotemplate. Moreover, it exhibited reasonable mechanical stability in order to study the applicability of the biomorphic catalyst in a technical catalytic process. A bio-inspired catalytic reactor utilising the self-supporting ZSM-5 scaffold in monolithic configuration was developed in order to test the catalytic performance of the material.
Sponge-gourds, the fruit of Luffa cylindrica, are widely used throughout the world. Despite that, there is lack of scientific data concerning thermal, mechanical, and chemical properties of these fibers. Sponge-gourds biocomposites are a novel use of these fibers, but a better understanding of their surface characteristics is necessary to maximize their potential use. In this work, different chemical treatments were conducted on the fibers with aqueous solutions of NaOH 2%, or methacrylamide (1–3%) at distinct treatment times. L. cylindrica was characterized via chemical analysis and analytic techniques such as FTIR, XPS/ESCA, X-Ray, TGA and SEM. Methacrylamide 3% treatment for all times (60, 120 or 180 min) severely damaged the fibers. NaOH, on the other hand, showed the same beneficial effect regarding enhancement of surface area and thermal stability together with similar levels of lignin and hemicellulose extraction, without causing exaggerated harm to fiber integrity.
The turtle's shell acts as a protective armor for the animal. By analyzing a turtle shell via finite element analysis, one can obtain the strength and stiffness attributes to help design man-made armor. As such, finite element analysis was performed on a Terrapene carolina box turtle shell. Experimental data from compression tests were generated to provide insight into the scute through-thickness behavior of the turtle shell. Three regimes can be classified in terms of constitutive modeling: linear elastic, perfectly inelastic, and densification regions, where hardening occurs. For each regime, we developed a model that comprises elasticity and densification theory for porous materials and obtained all the material parameters by correlating the model with experimental data. The different constitutive responses arise as the deformation proceeded through three distinctive layers of the turtle shell carapace. Overall, the phenomenological stress-strain behavior is similar to that of metallic foams.
Ultralight (<10 milligrams per cubic centimeter) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. We present ultralight materials based on periodic hollow-tube microlattices. These materials are fabricated by starting with a template formed by self-propagating photopolymer waveguide prototyping, coating the template by electroless nickel plating, and subsequently etching away the template. The resulting metallic microlattices exhibit densities ρ ≥ 0.9 milligram per cubic centimeter, complete recovery after compression exceeding 50% strain, and energy absorption similar to elastomers. Young's modulus E scales with density as E ~ ρ(2), in contrast to the E ~ ρ(3) scaling observed for ultralight aerogels and carbon nanotube foams with stochastic architecture. We attribute these properties to structural hierarchy at the nanometer, micrometer, and millimeter scales.
The mechanisms underlying the toughening in rigid natural composites exhibited by the concentric cylindrical composites of spicules of hexactinellid sponges, and by the nacre (brick-and-mortar) structure of mollusks such as Haliotis rufescens (red abalone), as well as the crossed-lamellar structure of Strombus gigas (queen conch) show commonalities in the manner in which toughening takes place. It is proposed that crack diversion, a new kind of crack bridging, resulting in retardation of delamination, creation of new surface areas, and other energy-dissipating mechanisms occur in both natural systems. However, these are generally different from the toughening mechanisms that are utilized for other classes of structural materials. Complementary to those mechanisms found in rigid natural ceramic/organic composites, special architectures and thin viscoelastic organic layers have been found to play controlling roles in energy dissipation in these structures.
Load-bearing biological materials such as shell, mineralized tendon and bone exhibit two to seven levels of structural hierarchy based on constituent materials (biominerals and proteins) of relatively poor mechanical properties. A key question that remains unanswered is what determines the number of hierarchical levels in these materials. Here we develop a quasi-self-similar hierarchical model to show that, depending on the mineral content, there exists an optimal level of structural hierarchy for maximal toughness of biocomposites. The predicted optimal levels of hierarchy and cooperative deformation across multiple structural levels are in excellent agreement with experimental observations.
High fidelity calcium carbonate and hydroxyapatite (bio) inorganic replicas of the fibrous network of the dried fruit of Luffa cylindrica are described, utilizing a facile synthetic route. The loofa sponge is a highly complex macroscopic architectural template, an inexpensive and sustainable resource. In the context of the morphosynthesis, the capability of replication of the loofa sponge opens the possibility of the use of biodiversity in obtaining new materials. We would like to emphasize that the template proposed in this paper, makes possible the preparation of inorganic replicas with a very desirable size, on the centimeter scale. This fact is innovative with respect to inorganic replicas described in the literature, which predominate at the micrometric scale, limited to the original size of the template.
This important study focuses on the way in which structures and materials can be best designed to absorb kinetic energy in a controllable and predictable manner. Understanding of energy absorption of structures and materials is important in calculating the damage to structures caused by accidental collision, assessing the residual strength of structures after initial damage and in designing packaging to protect its contents in the event of impact. Whilst a great deal of recent research has taken place into the energy absorption behaviour of structures and materials and significant progress has been made, this knowledge is diffuse and widely scattered. This book offers a synthesis of the most recent developments and forms a detailed and comprehensive view of the area. It is an essential reference for all engineers concerned with materials engineering in relation to the theory of plasticity, structural mechanics and impact dynamics. © 2003 Woodhead Publishing Limited Published by Elsevier Ltd All rights reserved.
In this preliminary study, the potential of loofah fiber as reinforcement material for polymer-bonded composites was investigated. Tensile and flexural properties of loofah fiber reinforced plastic were characterized and evaluated. The mechanical properties of the composite have been determined as a function of different method of loofah fiber preparation. The fiber-matrix interaction and fiber/matrix volume were also determined using a stereomicroscope. Results of mechanical properties, at least in this study showed that loofah fiber reinforced with unsaturated polyester are typical anisotropic material since the loofah is generally controlled by the network of fibers in multi-directions. The concentration of fibers in the loofah itself has a significant effect on the mechanical properties as shown from the results of transverse and longitudinal direction. The tensile and flexural modulus varied depending on the sample preparation of the composite and the direction of loading.
o 52' 31" West, 550 m above m.s.l.), Paraiba state. L. cylindrica showed a very good performance as a solid substrate for the development of the biofilm aggregating microorganisms capable of metabolizing both organic and inorganic compounds adsorbed on it, particularly those responsible for nitrification. The efficiency of nitrification varied within the range of 82 - 95% with a mean of 88%. The final effluent had an ammonia nitrogen mean concentration of 5 mg.L - 1 , which is less than that recommended by the National Council for the Environment for discharges into receiving bodies in Brazil.
The mechanical properties (the moduli and collapse strengths) of three-dimensional cellular solids or foams are related to the properties of the cell wall, and to the cell geometry. The results of the analyses give a good description of a large body of data for polymeric foams.
This paper investigates the liquid absorbency potential of the vegetal cell-fibers (CF) of Luffa cylindrica (LC) in relation to their microscopic morphology. Absorption after drainage and centrifugation, involving deionized water and saline solutions, is measured on both the raw fibers of the vegetal net and the cell-fibers previously extracted from ligneous fibrous strands (FS) with NaOH-anthraquinone alkali treatment. The microspongy structure of the raw Fs-luffa, observed in the vegetal material by scanning electron microscopy (SEM), is formed by multicellular fibers (from 250 to 500) bonded together with a large lumen (5 to 30 μm) and containing small punctuations along the fibers as interconnections. Liquid absorption results show that this original structure of these promising fibers should contribute to good absorption capacity: 18.4g/g and 22.6g/g are respectively obtained with for broken raw FS and CF-luffa fluff treated by 5 wt % NaOH. Their absorption capacity for liquid improves with an additional formaldehyde treatment.
The onset of densification of cellular solids represents the start of the cell wall interactions, which enhance the compressive resistance of a cellular solid. Currently, there exists ambiguity in the definition and uncertainty in the determination of the compressive strain, from which the densification regime starts. The onset strain of densification and the densification strain are defined and distinguished in the present study. Several commonly used methods to determine the onset strain of densification are examined. It is shown that the method based on the energy absorption efficiency curve gives unique and consistent results. Two types of energy absorption efficiency curves are identified. Further justifications of the use of the energy absorption efficiency method are provided for various types of cellular solids.
The tensile and compressive stress-strain behavior of closed cell aluminium alloy foams (trade name Alulight) has been measured and interpreted in terms of its microstructure. It is found that the foams are anisotropic, markedly inhomogeneous and have properties close to those expected of an open cell foam. The unloading modulus and the tensile and compressive yield strengths increase non-linearly with relative density. The deformation mechanisms were analyzed using image analysis software and a d.c. potential drop technique. The scatter in results is attributed to imperfections within the foam. These include non-uniform density, weak oxide interfaces, and cell faces containing voids and cracks.
It has been well established that ALPORAS® foams is a strain rate sensitive material. However, the strain rate effect is not well quantified as it is not unusual for strain rate to vary during high speed compression. Moreover, according to previous research, aluminium foams, especially ALPORAS® foams, behave differently at low and high strain rates. Therefore, different plastic deformation mechanisms are expected for low and high strain rate loadings as a result of micro-inertia of cell walls. In this paper, the strain rate effect on the energy dissipation capacity of ALPORAS® foam was investigated experimentally by using a High Rate Instron Test System, with cross-head speed up to 10m/s. The compressive tests were conducted over strain rates in the range of 1×10−3 to 2.2×102s−1, with each test being at a fairly constant strain rate. An energy efficiency method was adopted to obtain the densification strain and plateau stress. The effect of strain rate and the foam density was well presented by empirical constitutive models. The experimental data were also discussed with reference to the recent results by other researchers but with different range of strain rates. An attempt has been made to qualitatively explain the observed decrease of densification strain with strain rate.
Recently, there is a high interest in using light-weight metallic foams (e.g., Al and Mg) for automotive, railway and aerospace applications where weight reduction and improvement in comfort are needed. Metallic foams also have a potential for absorbing impact energy during the crashing of a vehicle either against another vehicle or a pedestrian. In this study, enhancement of absorption energy in a closed-cell structure has been performed by an increase in the aspect ratio of cell-wall thickness against the cell-edge length with the reduction of cell size. The absorbed energy in a modified foam is estimated comparing with that in a conventional ALPORAS with the same relative density.
The use of sponge gourd (Luffa cylindrica) as reinforcement in resin matrix composite materials is evaluated. The morphology of the fibrous vascular system of Luffa's fruit is presented and the advantages of using this natural mat material are highlighted. The use of untreated Luffa does not increase the mechanical properties of the bare resin. Nevertheless, its incorporation produces a change on the fracture mode of the composites from an abrupt one to a controlled and safer one. This result and the values obtained from mechanical tests show that, without any surface treatment, Luffa already has a high potential use as a core material in hybrid composites.
This paper focuses on the structural design of the microscopic architecture of a lattice material with regular octet-truss cell topology and on the multiscale design of an axially loaded member manufactured of this type of cellular solid. The rationale followed here hinges on the coincidence of the failure modes of a stretching dominated lattice material, which experiences two types of microscopic failure modes, namely, elastic buckling and plastic yielding. A lattice material that fails by the elastic buckling of its cell elements without reaching the plastic yielding is far from optimum. To avoid this event and improve the material strength, we first start to tailor the structural efficiencies of the cell elements. We show that by shaping the cell element cross-sections, the lattice material buckling resistance can increase until it equals the cell element yield strength, thereby exploiting fully the lattice material strength. The coincidence of these two failure modes is the structural criterion used to develop selection charts for the micro-structural design of the octet-truss lattice material. In the second part of the paper, we examine the design of a structural column manufactured by regular octet-truss lattice material. We show that to maximize the structural failure resistance at both the structural and the material levels, the global buckling and the yielding failure of the column must occur simultaneously with the microscopic failure modes of the lattice material, namely the local buckling and the yielding of its microscopic cell elements. The paper concludes by illustrating how the micro-truss geometry and the column cross-section can be simultaneously designed to fully exploit the strength of the material and the overall macrostructure.
The mechanical properties at room temperature of three polymeric foams (namely EPP, PUR and PS/PA foams) have been experimentally evaluated in both static and impact loading conditions. The energy absorption characteristics have been examined both through the energy-absorption diagram method and through the efficiency diagram method. The meaning of the efficiency parameter, already used in the literature, has been explained in a proper, satisfactory way. It is shown that the maximum of the efficiency identifies the condition for optimal energy absorption of the foam, while the maximum stress reaches a value limited through other design considerations. The efficiency diagram method is then used to obtain synthetic diagrams useful to characterize the material and to help the design of energy absorbing components. These synthetic selection diagrams are obtained for the three tested materials. Finally, some consideration are drawn comparing the mechanical performance of the three considered types of foams and their dependency on density.
Learning from nature is a promising way for designing and fabricating new materials with special properties. As the first step, we need to understand the structures and properties of the natural materials. In this work, we paid attention to the mesogloea of an edible jellyfish (Rhopilema esculenta Kishinouye) and mainly focused on its structure, mechanical and swelling properties. Scanning electron microscope (SEM) investigations show that jellyfish mesogloea has a well-developed anisotropic microstructure, which consists of nano-sized membranes connected with many fibres. The tensile and compressive properties of swollen and dried jellyfish mesogloea samples are measured. The jellyfish mesogloea displays very high tensile strength (0.17 MPa) and compressive strength (1.43 MPa) even with 99 wt % water. The mechanical properties of jellyfish mesogloea exceed most synthetic hydrogels with similar or even lower water contents. Swelling in acidic and basic buffer solutions weakens the mechanical properties of jellyfish mesogloea. The dried jellyfish mesogloea has very high tensile strength and modulus, which are very similar to those of synthetic plastics. The swelling properties of jellyfish mesogloea in solutions with different pH values were studied. The jellyfish mesogloea exhibits pH-sensitive and anisotropic swelling properties. The jellyfish mesogloea swells (expands) in height but deswells (shrinks) in length and width, without significant change in the volume. This phenomenon has never been reported for synthetic hydrogels. This study may provide gel scientists new ideas in designing and fabricating hydrogels with well-defined microstructures and unique mechanical and swelling properties.
Nature, to a greater extent than engineering, takes advantage of hierarchical structures. These allow for optimization at each structural level to achieve mechanical efficiency, meaning mechanical performance per unit mass. Palms and bamboos do this exceptionally well; both are fibre-reinforced cellular materials in which the fibres are aligned parallel to the stem or culm, respectively. The distribution of these fibres is, however, not uniform: there is a density and modulus gradient across the section. This property gradient increases the flexural rigidity of the plants per unit mass, mass being a measure of metabolic investment made into an organism's construction. An analytical model is presented with which a 'gradient shape factor' can be calculated that describes by how much a plant's bending efficiency is increased through gradient structures. Combining the 'gradient shape factor' with a 'microstructural shape factor' that captures the efficiency gained through the cellular nature of the fibre composite's matrix, and a 'macroscopical shape factor' with which the tubular shape of bamboo can be described, for example, it is possible to explore how much each of these three structural levels of the hierarchy contributes to the overall bending performance of the stem or culm. In analogy, the bending efficiency of the commonly used wood-based composite medium-density fibreboard can be analysed; its property gradient is due to its manufacture by hot pressing. A few other engineered materials exist that emulate property gradients; new manufacturing routes to prepare them are currently being explored. It appears worthwhile to pursue these further.
The fracture properties of spruce and yew were studied by in-situ loading in an environmental scanning microscope (ESEM). Loading was performed with a micro-wedge splitting device in the TR-crack propagation direction. The emphasis was laid on investigating the main mechanisms responsible for a fracture tolerant behavior with a focus on the reaction wood. The fracture mechanical results were correlated with the features of the surface structure observed by the ESEM technique, which allows loading and observation in a humid environment. Some important differences between the reaction wood and normal wood were found for both investigated wood species (spruce and yew), including the formation of cracks before loading (ascribed to residual stresses) and the change of fracture mode during crack propagation in the reaction wood. The higher crack propagation resistance was attributed mainly to the different cell (i.e. fiber) geometries (shape, cell wall thickness) and fiber angle to the load axis of the reaction wood, as basic structural features are responsible for more pronounced crack deflection and branching, thus leading to crack growth retardation. Fiber bridging was recognized as another crack growth retarding mechanism, which is effective in both wood species and especially pronounced in yew wood.
The approach used by Materials Science and Engineering is revealing new aspects in the structure and properties of biological materials. The integration of advanced characterization, mechanical testing, and modeling methods can rationalize heretofore unexplained aspects of these structures. As an illustration of the power of this methodology, we apply it to biomineralized shells, avian beaks and feathers, and fish scales. We also present a few selected bioinspired applications: Velcro, an Al2O3-PMMA composite inspired by the abalone shell, and synthetic attachment devices inspired by gecko.
In this work the annual plant called Luffa cylindrica (LC) has been characterized and used to prepare macroscopic lignocellulosic fibers and cellulosic nanoparticles, viz. microfibrillated cellulose (MFC) and whiskers, each of which can be used as a reinforcing phase in bionanocomposites. The morphological, chemical, and physical properties of LC fibers were first characterized. The contents of lignin, hemicellulose, and other constituents were determined, and scanning electron microscopy (SEM) observations were performed to investigate the surface morphology of the LC fibers. Sugars contents were determined by ionic chromatography, and it was shown that glucose was the main sugar present in the residue. MFC and whiskers were prepared after chemical treatments (NaOH and NaClO2), purifying cellulose by eliminating lignin and hemicellulose. Transmission electron microscopy (TEM) and SEM made it possible to determine the dimensions of LC whiskers and MFC. Tensile tests were carried out to investigate the mechanical properties of LF nanoparticles.
The effects of moisture on the mechanical properties of the spicules of the sponge Euplectella aspergillum have been investigated. Determinations were made with the aid of a dynamic mechanical analyzer in both the static and dynamic modes, as well as imaging of the failed surfaces with scanning electron microscopy. For comparison purposes, melt-grown glass fibers of similar diameters were also studied in both distilled water and seawater. That exposure reduced both the stiffness and strength of the spicules. In addition, the energy required to achieve complete failure decreased in moist environments. The data for the wet spicules in both aqueous media showed decreasing values of energy dissipated until catastrophic failure compared to dry samples. The strength of wet glass decreased when compared with the dry condition, and the elastic modulus was also reduced. The most marked influence of moisture was seen in the damping effects in moist spicule samples that were nearly an order of magnitude larger than the damping of dry spicules. This effect was attributed mainly to plasticization of the thin organic layers.
Copyright: 2008 Elsevier Ltd This review deals with a recent study of the literature on the various aspects of cellulosic fibres and biocomposites. Cellulosic fibre reinforced polymeric composites are finding applications in many fields ranging from construction industry to automotive industry. The pros and cons of using these fibres are enumerated in this review. The classification of composites into green composites, hybrid biocomposites and textile biocomposites are discussed. New developments dealing with cellulose based nanocomposites and electrospinning of nanofibres have also been presented. Recent studies pertaining to the above topics have also been cited. Finally, the applications of cellulosic fibre reinforced polymeric composites have been highlighted
A circulating loop bioreactor (CLB) with cells immobilized in loofa sponge was constructed for simultaneous aerobic and anaerobic processes. The CLB consists of an aerated riser and a non-aerated downcomer column connected at the top and bottom by cylindrical pipes. Ethanol production from raw cassava starch was investigated in the CLB. Aspergillus awamori IAM 2389 and Saccharomyces cerevisiae IR2 immobilized on loofa sponge were placed, respectively, in the aerated riser column and non-aerated downcomer column. Both alpha-amylase and glucoamylase activities increased as the aeration rate was increased. Ethanol yield and productivity increased with an increase in the aeration rate up to 0.5 vvm, but decreased at higher aeration rates. The CLB was operated at an aeration rate of 0.5 vvm for more than 600 h, resulting in an average ethanol productivity and yield from raw cassava starch of 0.5 g-ethanol l(-1) x h(-1) and 0.45 g ethanol/g starch, respectively. In order to increase ethanol productivity, it was necessary to increase the dissolved oxygen (DO) concentration in the riser column and decrease the DO concentration in the downcomer column. However, increasing the aeration rate resulted in increases in the DO concentration in both the riser and the downcomer columns. At high aeration rate, there was no significant difference in the DO concentration in the riser and downcomer columns. The aeration rate was therefore uncoupled from the liquid circulation by attaching a time-controlled valve in the upper connecting pipe. By optimizing the time and frequency of valve opening, and operation at high aeration rate, it was possible to maintain a very high DO concentration in the riser column and a low DO concentration in the downcomer column. Under these conditions, ethanol productivity increased by more than 100%, to 1.17 g l(-1) x h(-1).
The dried fruit from Luffa cylindrica (loofa sponge, LS), which represents a new chitinous source material, was used as a 3-D scaffold for the culture of rat hepatocytes. With the macroporous structure and large pore size (ca. 800 microm) of LS, cell loading to the scaffold should be carried out by dynamic seeding with continuous shaking throughout the seeding period. Hepatocytes attach well to the surface of loofa fibers after seeding and maintain their round shapes. The initial ammonia removal and urea-N synthesis rates of hepatocytes immobilized within LS slightly decreased with increasing cell densities, but their metabolic activities were comparable to or better than those in monolayer culture on tissue culture polystyrene control surfaces. Both urea-N synthesis and albumin secretion rates could be maintained up to 7 days for cells immobilized within LS and spheroid-like cell aggregates could be found after the second day.
Although strong and stiff human-made composites have long been developed, the microstructure of today's most advanced composites has yet to achieve the order and sophisticated hierarchy of hybrid materials built up by living organisms in nature. Clay-based nanocomposites with layered structure can reach notable stiffness and strength, but these properties are usually not accompanied by the ductility and flaw tolerance found in the structures generated by natural hybrid materials. By using principles found in natural composites, we showed that layered hybrid films combining high tensile strength and ductile behavior can be obtained through the bottom-up colloidal assembly of strong submicrometer-thick ceramic platelets within a ductile polymer matrix.
Biofibres and biocomposites. Carbohydrate Polymers
- M J John
- S Thomas
John, M.J., Thomas, S., 2008. Biofibres and biocomposites. Carbohydrate Polymers 71, 343-364.