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In this study, we seek to understand the flexural behavior of a natural fiber reinforced composite in more depth by integrating a powerful statistical analysis into the experimental design method. Woven fabric reinforced biocomposites were analyzed through the Design of Experiments (DoE) methodology. We attempt in that manner to understand the effect of noise factors (uncontrollable variables) and reduce process variations within the fabrication process. Analysis of Variance (ANOVA) is carried out on the acquired experimental data to find the significant effect of input parameters along with their interactions. Each of the process control factors studied at two levels of high and low values. We estimated the main linear effects of the factors which are confounded with two-factor and three-factor interactions (two-way and three-way). Maximum flexural strength and stiffness of 44.83 MPa and 4.70 GPa were attained. Significant correlations found between suction point and mold filling time for the vacuum bagging process which significantly affected all flexural properties when on low and high levels respectively.
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... The aforementioned problems on synthetic fibre can be fixed by using the natural fibres as reinforcement for polymer composite fabrication (Faruk et al., 2014) Natural fibre can be considered as an alternative to synthetic fibre reasons been due to their high strength, low cost, lightweight, biodegradability, renewability, low cost, low energy requirements, ease of separation, abundant and local availability (Li et al., 2007). Examples of natural fibres that have attracted research include sisal, kenaf, jute, coir flax, and bamboo fibre (Baley et al. 2018;Prasob and Sasikumar, 2019;Koronis et al., 2017;Sen and Reddy 2011;Saba et al., 2015). Natural fibres can be grouped according to their origin; these are animals, plants, or minerals. ...
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Bamboo fibres of 1 to 3 mm sizes were milled to particle size of approximately 100μm using a hammer mill. The bamboo sawdust (BS) was chemical treated using NaOH of concentration 6 % wt/v for 72 h at room temperature. Dried bamboo sawdust was mixed with polyester at different weight ranging from 0 % to 24 % wt. %. The composites were tested for the tensile properties. Theoretical mechanical equations were used to predict the properties. Polyester curve showed linear deformation behaviour with the stress rising to a maximum value with signs of yielding before fracture. The tensile strength of polyester was 49.38 MPa, increasing to a maximum of 76.47 MPa at 24 % wt. of BS. At zero wt. % of BS the modulus was 1381 MPa, and increased to 2587.08 MPa at 24 % wt. The strain decreased from 5.5 % at pure polyester to 3.32 % at 24 % wt. of BS. A maximum percentage decrease of ≈ 40 % for the strain was recorded, an indication of the brittleness of the composites. Prediction of mechanical properties using published theories of mechanical equations (tensile strength and Young' modulus) with experimental results of bamboo sawdust reinforced polyester composites was investigated. The models used were rule of mixture (Parallel and Series), Hirsch's and Halpin-Tsai models. Irrespective of the equation used tensile strength increased with increase in the volume fraction of BS. The best correlation between theoretical and experimental tensile strength was predicted using the Halpin-Tsai model, followed by Hirsch, Parallel and Series respectively. Depending on the volume or weight fraction the percentage prediction was between 79 and 88 % for Parallel and Series models and between 97 and 99 % for Halpin-Tsai and Hirsch models.
... A Minitab response optimizer tool is applied to reveal how various experimental settings change the expected responses for a stored model [23]. It is used to get the optimal control factors for optimizing both the MRR and the SR together as shown in Fig. 5. ...
Article
Wire Electrical Discharge Machining (WEDM) is a non-traditional thermal machining process used to manufacture irregularly profiled parts. Machining of ductile cast iron (ASTM A536) under several machining factors, which affect the WEDM process, is presented. The considered machining factors are pulse on time (Ton), pulse off (Toff), peak current (Ip), voltage (V), and wire speed (S). To optimize the machining factors, their setting is performed via an experimental design using the Taguchi method. The optimization objective is to achieve maximum Material Removal Rate (MRR) and minimum Surface Roughness (SR). Additionally, the analysis of variance (ANOVA) is used to identify the most significant factor. Also, a regression analysis is carried out to forecast the MRR and SR dependent on defined machining factors. Depending on consequences, the best regulation factors for reaching the maximum MRR are Ton = 32 μs, Toff = 8 μs, Ip = 4 A, S = 40 mm/min. and V = 70 volt. Whereas, the optimal control factors that achieve the minimum SR is Ton = 8 μs, Toff = 8 μs, Ip = 2 A, S = 20 mm/min, and V= 30 volt. It is hypothesized that the perfect combination of control factors that achieves minimum SR and maximum MRR is Ton = 8 μs, Toff = 8 μs, Ip=5 A, S=50 mm/min. The microstructure of the machined surface in the optimal machining conditions shows a very narrow recast layer at the top of the machined surface.
... Engineers do deliberate modifications in input parameters and then ascertain the corresponding variations in output factors. Process setting that reduces process variability and works more reliably in operating atmosphere can be selected based on the "Design of Experiments (DOE)" which is used for finetuning the fabrication methods by choosing the best factors [12]. In this investigation, Taguchi method "a powerful tool for parameter design of performance characteristics" is used. ...
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Since fabric-polymer laminates are being used in several engineering applications, it is imperative to compute and analyse the performance of any novel fabric reinforced polymer laminates while machining. Given these perspectives, an endeavor has been made to formulate a polymer sandwich laminate by incorporating industrial by-product & natural fibres and to machine the sandwich laminate using Abrasive Water Jet (AWJ) machining. For enhancing the machining process, a multi-objective optimisation is employed. In this study 2 wt.% fumed silica added epoxy reinforced with linen fabric (3 layers) & jute fabric (2 layers) sandwich laminate is machined using AWJ machining and the optimal combination of machining parameters are predicted using Taguchi-grey relational technique for multi-response characteristics such as Material Removal Rate (MRR) and Kerf Inclination (KI). For multi-response optimisation the traverse speed, the standoff distance, and the abrasive flow rate are considered as input machining parameters. In AWJ machining, the MRR increases with traverse speed and abrasive flow rate. Whereas, passing of higher abrasive particles at higher traverse speed causes reduction in kerf inclination. Using Taguchi-grey relational analysis (GRA), the optimal combination of AWJ machining process parameters for maximum MRR and minimum kerf inclination is attained. For determining the greatest significant parameter in optimisation, ANOVA is carried out. The standoff distance has the highest influence on multi performance characteristics of AWJ machining of laminate followed by traverse speed and abrasive flow rate. The confirmation test revealed that the grey relation grade value has improved by 1.81% from predicted grey relation grade value.
... The discussed beams were made of eight-layer GFRP laminate. Koronis et al. (2017) investigated the flexural behaviour of a natural fibre reinforced composite in more depth by integrating a powerful statistical analysis into the experimental design method. ...
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The effects of different boundary conditions on the composite laminate containing embedded and through-the-width delamination under bending load are investigated analytically based on a developed Layerwise Higher Order Shear Deformation Theory (LHSDT) and the results are compared with the three-dimensional Finite Element Method (FEM). Contact energy has been calculated. The results demonstrate the ability of the presented method of predicting the displacement fields of a composite laminate containing delamination and obtaining stress-strain curves in bending condition. Moreover, strain energy release rate can be achieved using the obtained displacements to evaluate the initiation of delamination propagation around the boundaries of the considered delaminated region. Furthermore, the failure of the laminate will be predicted using conventional theories such as Tsai-Wu.
... Natural fiber has been considered as an alternative to synthetic fiber due to their advantages such as lightweight, renewability, biodegradability, low cost, low energy requirements, abundant availability, high strength and elasticity modulus [5,6]. Plant fibers that are commonly studied include kenaf, jute, flax, sisal, coir and bamboo fiber [7][8][9][10][11]. However, to the best of our knowledge limited study on bamboo fiber composite is available, and hence this is the aim of this work. ...
Article
This paper presents the thermal and mechanical properties of bamboo fiber reinforced composite (BFRC) derived from Gigantochloa scortechinii. The bamboo fibers were prepared through chemical treatment by sodium hydroxide (NaOH) followed by physical milling method. The thermal characteristics of the bamboo fiber and its polymer composite were analysed using a thermogravimetric analysis and differential scanning calorimetric. The functional groups and crystallinity of the fiber were analysed with Fourier transform infrared and x-ray diffraction spectroscopy. Meanwhile, the fiber morphology was examined using a scanning electron microscope. The BFRCs with fiber volume fractions ranging from 0 % to 40 % embedded in three thermoset resins (epoxy, polyester, vinyl ester) were subjected to tensile and flexural tests and the fracture pattern was examined. The NaOH concentration of 10 % with soaking duration of 48 h was found to produce a bamboo fiber with the highest ultimate tensile and modulus strength. The tensile and flexural properties of all the BFRCs were found to be directly proportional to the fiber volume fractions. It was found that the bamboo fiber reinforced epoxy composite (BFREC) with 40 % fiber volume fraction exhibited the highest tensile and flexural strength compared to polyester and vinyl ester composites. The method of bamboo fiber composite preparation in this work may serve as a useful guide to produce a strong BFRC for external strengthening of buildings and structures.
... Three-dimensional (3D) composites have been developed by advanced textile techniques of weaving, braiding and stitching to overcome fatal flaws with interlayer properties of conventional 2D laminates. 3D angle-interlock woven composites have particularly attractive materials in primary load-bearing structures and have been widely applied in aeronautics and astronautics industries [1][2][3][4][5]. ...
Article
A new 3D finite element model (FEM) is established based on the actual microstructure of 3D angle-interlock woven composites, considering the configuration of outer yarns, yarns cross-sectional deformation of and spatial orientation. A prediction of the meso-scale mechanical response and effective elastic properties of 3D angle-interlock woven composites have been presented to verify the validation of 3D FEM. The effects of woven parameters on the mechanical properties are investigated in detail. The results show that 3D FEM precisely simulates the spatial geometric characteristics of 3D angle-interlock woven composites. The reasonable overall stress fields and local stress distribution can be identified and well support the strength prediction. It is convenient to predict all the elastic constants of 3D angle-interlock woven composites with different parameters simultaneously using 3D FEM. The calculated results show that 3D angle-interlock woven composites have good mechanical properties and can be considered as anisotropy materials in a macro-scale. In addition, the warp yarn density, weft yarn density and fiber volume fraction are important factors affecting the mechanical properties of 3D angle-interlock woven composites.
... In recent times modeling and optimization of composite materials for improved properties and usability has been subject to intensive research [10][11][12][13][14][15][16][17][18][19][20]. In the research of Nwobi-Okoye and Ochieze [21], they used response surface model (RSM) and Artificial Neural Network (ANN) to predict the response and optimize the hardness of A356 alloy/ CHp particulate composite. ...
Article
In this study Response Surface Methodology (RSM), artificial neural network (ANN) and non-dominated sorting genetic algorithm-II (NSGA-II) were used for modeling and multi objective optimization of Al 6351/ Egg Shell Reinforced Composite. The properties of the composite optimized were toughness and hardness whose values vary in response to changes in production process variables namely: stirring speed, stirring time and preheat temperature. An experimental design using Box-Bernken Design was used to develop an RSM model for modeling the variations in the mechanical properties of the fiberboard in response to variations in process parameters. An ANN model was equally used to predict the properties of the composite. Subsequently the ANN was used as the fitness function for multi objective optimization of the produced composite using NSGA-II. The results of the study showed that RSM effectively modeled the properties of the composite. Also the correlation coefficient of the experimental responses and ANN predictions of the properties were excellent with the minimum value being 0.9982. The optimized Pareto front of the NSGA-II algorithm would be an excellent design guide for practical applications of Al 6351/ Egg Shell Reinforced composite in engineering design.
... DOE is widely used in engineering/science research, not only for optimizing manufacturing processes [24,25] but also for evaluating idea generation methods [26]. Additionally, the full factorial creativity experiments that we have come across focus on either the design environment [27] or ideation techniques [28], which is unlike our focus on the effect of information in design briefs. ...
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This study aims to understand how information in design briefs affects the creativity of design outcomes. We tested this during a Collaborative Sketching (C-Sketch) ideation exercise with first-year undergraduate student designers. We focus on four types of stimuli - quantitative requirements, a visual example (video), a physical example, and contextual information - and we measure creativity according to three metrics – novelty, appropriateness, and usability with either the participants’ gender or the gender diversity of the participants’ groups. The findings suggest that the main effect of providing a video example results in high appropriateness and usability scores but low novelty scores, and that physical-contextual briefs have high novelty and usability scores. In addition, we did not find any correlation between gender or gender diversity and creativity scores.
... Composite specimens were prepared as per the standard test methods for three -point flexural tests. The composite samples of rectangular shape were prepared according to ASTM D 790 for three-point flexural test [14]. Flexural tests were conducted on a Nano Servo Hydraulic UTM Plug N Play machine (ITW BISS make) of 25kN capacity available at CBIT, Hyderabad with a cross head speed of 1.5mm/ min with 64 mm support span. ...
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Composite materials are formed by two or more constituents at macroscopic level. Type and form of fiber plays a vital role in imparting required properties to the composite. Many researchers contributed to the development of artificial fiber composites which are not environmental friendly in nature. Sizable research is also done in the area of natural fiber composites. Human hair is a non-biodegradable waste available in abundant quantity across the world, but is rarely explored for applications in engineering fields. In the present study, a review on behavior of human hair fibers was made to understand their suitability as a reinforcing material in composites. Morphology of the hair fibers is reviewed and the density of the hair fibers was determined using Archimedes principle. Tensile strength of the hair fibers is experimentally estimated. Chemical resistivity and burning tests were conducted. Tensile and flexural properties of hair fiber reinforced polyester composite were experimentally determined and compared.
... Mashouf Roudsari et al. statistically correlated the mechanical properties of bio composites using ANOVA [20]. Koronis et al. carried out an ANOVA test, based on the obtained experimental data to find the significant effect of input parameters [21]. ...
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The aim of this research is partial replacement of plain woven Kevlar 29(K) with naturallywoven cocous nucifera sheath (CS) waste. Laminated K/CS reinforced epoxy hybrid com-posites were fabricated by hand lay-up method followed by hot compression moulding with105?C temperature at 275 bar pressure for 1 h. The total fibre loading of the hybrid com-posite was maintained 45 wt.% and the ratio of Kevlar and Cocous nucifera sheath varies inweight fraction of 100/0, 75/25, 50/50, 25/75, and 0/100. Mechanical (tensile, flexural, impact),moisture diffusion and morphological behaviour of the laminated composites were evalu-ated. The results showed that the hybrid composites (75/25) declined the tensile strengthby 19% compared to Kevlar fabric reinforced epoxy composites. But, the hybrid composites(75/25) exhibited highest flexural strength (175 MPa) and flexural modulus (18 GPa) than pureKevlar reinforced epoxy composites. Moreover, the impact toughness of hybrid composites(86 kJ/m2) at 75/25 wt.% showed good agreement with the pure Kevlar fabric reinforced poly-mer composites (90 kJ/m2). From the moisture diffusion analysis, hybrid composites (75/25)exhibited better moisture resistance. Statistical analysis of the results has been carried outusing one way-ANOVA (analysis of variance) and it shows that there is a statically signifi-cant difference between the obtained mechanical properties of the laminated composites.Morphology of the tensile fractured laminates showed the delamination's, matrix crackingand fibre/matrix adhesion. From the results, it has been concluded that naturally wovenCocos nucifera sheath has the potential to replace Kevlar fabric in the polymer compositesexclusively for defence applications. © 2018 Brazilian Metallurgical, Materials and Mining Association.
... A number of automakers and academic studies have explored and presented practical examples of plant-based solutions for automotive parts including trim parts in dashboards, door panels, parcel shelves, seat cushions, backrests, cabin linings and so on [5,[9][10][11][12][13][14][15]. One can see an increasing interest in replacing fiberglass by introducing natural plant fibers such as jute, flax, hemp, sisal and ramie because of the environmental benefits achieved due to the density of natural fibers comparing to glass fibers [6,12,[16][17][18]. Subsequently, green composites LCA's more accurate assessment of environmental impact and the fact that it has a broader list of environmental indicators, it is time-consuming with respect to the complexity of each process step [38], i.e., setting up inventory data can be one of the most labor and time-intensive stages of an LCA [34]. ...
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This study considers a green composite under a twofold assessment; evaluating its process-based cost and environmental footprint profile. The initial objective was to project the manufacturing cost and allow for an additional material comparison of alternative scenarios in the resin transfer molding processes. The additional aim is to have an intermediate environmental assessment to assist in selecting materials and adjust manufacturing parameters which would minimize the energy spent and the CO2 emissions. As it has been noted in numerous applications, the incorporation of natural fiber fabrics, as opposed to glass fabrics, bring together weight savings and consequently cost savings. However, the economic analysis suggests that a glass reinforced composite is marginally cheaper at the production volume of 300 parts (1.9% lower cost) in contrast to a possible green solution (ramie). Considering jute instead of ramie as a reinforcement, the cost gets immediately lower, and further decreases with proposed improvements to the manufacturing process. Additional reduction of up to 10% in the production cost can be achieved by process upgrade. As indicated by the Eco-Audit analysis, 36% less energy and 44% CO2 per kilo will be generated, respectively when swapping from glass to ramie fabrics in the production of the automotive hood.
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The present work presents a material characterization for bio composites used for automotive industrial applications. The mechanical properties are utilized in the design of components of an electric micro-car for the green innovation of automotive industry. The composite material is homogenized as equivalent orthotropic material and its mechanical properties verified through laboratory testing. Finally a finite element model of some composite parts are analyzed by considering classical materials and innovative bio-composites. The comparison shows the valuable structural performances of the natural-based composites with respect to classical ones both in terms of cost, economical impact and mechanical performances.
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In the work, the design of experiments (DOE) method was used to obtain a modified epoxy resin of reduced fragility. As modifiers of commercial epoxy resin, urethane prepolymers with isocyanate terminal groups were used. Experimental points (samples of specified composition of resin prepolymer and a curing agent) were generated by the STATISTICA program module Design of Experiments using a central composition design. A study of the mechanical properties of modified resin samples was carried out for five intermediate values of input variables x1 (resin/hardener ratio) and x2 (modifier, wt %), designated for the normalized values 0, ± 1, and ±1.414. The STATISTICA algorithms analyzing the results of the practical implementation of the planned experiments allowed us to develop a model describing the dependence of the mechanical properties of composite resins on the composition and then to select the optimal compositions of epoxy resin for their practical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46761.
Chapter
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This chapter aims to present recent studies and applications of green composite materials in a variety of fields. Specifically, consumer products, biomedical applications, packaging, transportation, energy, construction, and sports and leisure will be treated in some depth. The reasons why green composites are finding ever wider application in these fields are presented, backed up by current research. Green composites have been substituting for fossil-derived plastics, metals and traditional GFRP with multiple gains in terms of economic and mechanical performance, environmental impact and public awareness. Some attention will be given to social and ethical issues that pertain to the possible generalized use of green composites, and its effect on local populations. The research community is currently very active in the field of green composites, and considerable breakthroughs are envisaged in the near future. Conclusions are drawn and future challenges and trends are provided throughout the chapter.
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Natural fiber reinforced polymer composites have emerged as a potential environmentally friendly and cost-effective alternative to synthetic fiber reinforced composites. Therefore, in the past decade, a number of major industries, such as the automotive, construction and packaging industries, have shown a considerable interest in the progress of new natural fiber reinforced composite materials. The availability of natural fibers and the ease of manufacturing have tempted researchers to study their feasibility of their application as reinforcement and the extent to which they satisfy the required specifications in tribological applications. However, less information concerning the tribological performance of natural fiber reinforced composite material is available in the literature. Hence, The aim of this bibliographic review is to demonstrate the tribological behavior of natural fiber reinforced composites and find a knowledge about their usability for various applications that tribology plays a dominant role. This review presents the reported work on natural fiber reinforced composites with special reference to the type of fibers, matrix polymers, treatment of fibers and test parameters. The results show that composites reinforced with natural fibers have an improvement in tribological properties and their properties is comparable with conventional fibers. In addition, fiber treatment and fiber orientation are two important factors can affect tribological properties where treated fibers and normal oriented fibers exhibit better friction and wear behavior. This review is trying to evaluate the effect of test parameter including normal load and sliding speed on tribological properties and the results vary based on type of reinforcement. Generally, due to their positive economic and environmental aspects, as well as their good tribological properties, natural composites are showing a good potential for employing in several applications.
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Bio-polymers have already penetrated in a great number of industries such as packaging and automotive in which they typically target the eco-minded consumers. Following that lead, novel green composites were prepared by resin transfer molding (RTM) and tested. Mechanical properties of ramie/bio-polyester composites were investigated in different fiber loadings. The results indicate that the flexural strength can be increased up to 138 % while tensile strength improved up to 31 %. The Young’s and bending moduli have also been increased up to 26 and 79 % respectively by the presence of the fiber fabrics. Environmental degradation tests have been performed on a set of coated and uncoated specimens. It is envisaged that an appropriate coating on the composite surfaces can preserve the durability properties under the range of exposure conditions examined by this study.
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The effective utilization of raw natural fibers as indispensable component in polymers for developing novel low-cost eco-friendly composites with properties such as acceptable specific strength, low density, high toughness, good thermal properties, and biodegradability is one of the most rapidly emerging fields of research in polymer engineering and science. In fact, raw natural fiber–reinforced composites are the subject of numerous scientific and research projects, as well as many commercial programs. Keeping in mind the immense advantages of raw natural fibers, in the present article we concisely review raw natural fiber/polymer matrix composites with particular focus on their mechanical properties.
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In this work, three types of woven (Plain, twill and Basket) composites are made of banana fibers/epoxy resin using hand-layup method. Mechanical properties (tensile, flexural and impact) of three types of woven composites are compared to evaluate the effect of weaving architecture on the properties. Dynamic Mechanical Analysis is carried out to analyse the visco-elastic behavior of the composite. Dynamic Mechanical Analysis is carried out in the temperature range of 40–140 °C at 0.1,1,10 Hz frequencies. Scanning Electron Microscopic analysis is carried out to investigate the fracture behaviour of the composite. From the investigation it is found that plain type of woven composite has better mechanical and dynamic mechanical behaviour.
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Polylactic acid (PLA) composites comprising up to 25 wt% cotton linter (CL) or up to 50 % maple wood fibre (WF) were prepared by compounding and injection moulding. A reduction of crystallinity in the PLA matrix was observed as a result of the thermal processing method. These PLACL and PLAWF composites provided excellent improvements in both stiffness (with increases in tensile and flexural modulus) and toughness (increases in notched impact strength) properties over the neat PLA resin, while the tensile and flexural strengths of the composites were generally unchanged, while the strain at break values were reduced in comparison to the neat PLA. DMA results indicated incorporating these fibres caused the mechanical loss factor (tan d) to decrease, suggesting better damping capabilities were achieved with the composites. SEM analysis of the impact fractured surfaces of the PLACL composites showed debonding-cavitation at the matrix-fibre interface while the PLAWF composites showed good wetting along its matrix-fibre interface. The composting of these composites up to 90 days showed that the degradation onset time was increased when increasing the fibre loadings, but the maximum degree of degradation and the maximum daily rates of degradation were decreased compared to neat PLA. On a weight basis of fibre loading, the PLACL composites had a quicker onset of biodegra-dation, a higher maximum daily rate of biodegradation and, overall, a higher degree of biodegradation at 90 days than the PLAWF composites, possibly due to the quicker thermal hydrolysis observed in the PLA matrix of the PLACL composites during processing and composting.
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The goal of this project is to develop new composites using fibers and resins from renewable resources. The ACRES (Affordable Composites from Renewable Sources) group at the University of Delaware has developed new chemistries to synthesize rigid polymers from plant oils. The resins produced contain at least 50% plant triglycerides and have mechanical properties comparable to commercially available synthetic resins such as vinyl esters, polyesters and epoxies. This project explores the development of all-natural composites by using natural fibers such as hemp and flax as reinforcements in the ACRES resins. Replacing synthetic fibers with natural fibers has both environmental and economic advantages. Unlike carbon and glass fibers, natural fibers are abundantly available from renewable resources. In terms of cost, natural fibers are cheaper than the synthetic alternatives. The natural fibers and plant-based resins have been shown to combine to produce a low cost composite with good mechanical properties. Tensile strength in the 30 MPa range has been obtained for a composite containing about 30 wt% Durafibre Grade 2 flax. The tensile modulus was found to be 4.7 GPa for a 40 wt% flax composite. Similar numbers where obtained for the hemp composites obtained from Hemcore Inc. Composites from renewable resources offer significant potential for new high volume, low cost applications.
Chapter
Natural fibers are gaining progressive account as renewable, environmentally acceptable, and biodegradable starting material for industrial applications, technical textiles, composites, pulp and paper, as well as for civil engineering and building activities. The fibers of the plants, such as flax, hemp, linseed, jute, sisal, kenaf, yucca, abaca, or ramie, have outstanding mechanical properties. The tensile strength of the natural fibers, for example, is comparable to the strength of high-tensile steel. However, the properties of the natural product “bast fiber” depend on the variety grown, the growing conditions, and the technology of processing. Basically, there are two working principles to separate the bast fibers from the wood. The conventional method uses breaking rollers, which alternating bend, buckle, and soften the stalks. This method requires an intensive retting of the stalks before processing. The retting is effected by microorganisms which dissolve the lignin and pectin of the stalk. Modern technologies use swing hammer mills in most cases. The fiber decortication is effected by impact stress of the hammers directly on the surface of the straw stalks. This working principle ensures a complete separation of the fibers from the wood even when processing freshly harvested, nonretted plants. The effective mechanical separation of the fibers and the wood inside the decorticator simplifies the subsequent fiber cleaning. The processed fibers have a fineness ranging between 2.5 and 15 tex. The fiber length varies in an adjustable range from 50 to 200 mm after processing. This length meets the requirements of many industrial applications. The optimal fiber length for processing of composites is between 2 and 4 mm only. Such lengths are cut after the fiber cleaning using special fiber-cutting machines.
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Cellulose fibers reinforced polylactic acid (PLA) bio-composites were developed by means of extrusion and injection molding process. The thermal properties of the developed bio-composites were investigated by thermo-gravimetric analysis (TGA). TGA results provided an upper limit of thermal processing window. The rheological properties of bio-composites showed shear thinning behavior and predicted a suitable temperature profile for processing the bio-composites. Heat distortion temperature of PLA/wood fibers (WP)/bioadimide bio-composites was slightly improved which could result in high temperature service life. Good interaction between short fibers and PLA resulted in better mechanical properties. With the addition of 1.3% bioadimide (bio-additive), tensile strength of bio-composites increased significantly. The impact strength of bio-composites was also considerably increased due to addition of bio-additive with bio-composites. This novel bio-additive was found very effective not only for fiber–matrix adhesion but also processability of bio-composites. X-ray computed tomography (CT) demonstrated cellulose fibers orientation and the fiber–matrix networking microstructures in a composite system.
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In this study, flexural behavior of nonwoven fabric reinforced sandwich composites from jute and polypropylene (PP) fibers was investigated. Jute/PP composite plates reinforced with jute/PP commingled nonwoven fabrics of different jute/PP fractions were used as facing materials in sandwich production. Balsa wood, polyester (PET) foam and PP honeycomb were used as core materials. Jute/PP nonwoven fabrics were treated with NaOH solution prior to sandwich production in an attempt to improve the fiber-matrix adhesion and the quality of facing-core bonding. The flexural behavior of the sandwiches was investigated experimentally as well as using Euler-Bernoulli and Timoshenko beam theories. The flexural properties of the sandwiches improved as the jute fiber content increases. Euler-Bernoulli model yielded smaller deflection values when compared to experimental results whereas Timoshenko model provided a good estimation of sandwich flexural properties. The effectiveness of fiber/matrix adhesion and facing/core bonding was determined by conducting scanning electron microscopy (SEM) analysis.
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Recently, there has been a growing interest in the use of naturally sourced fibers for use in composites design and manufacture. In this work, a structural design on automobile hood using natural flax fiber composite was performed. The structural design results of flax/vinyl ester composite hood were compared with the design results of metal hood structure. Through the structural analyses using commercial FEM software, it is confirmed that the designed automobile hood using natural composite is reasonable for structural safety, stability and weight. Through the structural test, it is confirmed that the designed hood structure is acceptable for structural safety and stability.
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The tools and technique used in the Design of Experiments (DOE) have been proved successful in meeting the challenge of continuous improvement over the last 15 years. However, research has shown that applications of these techniques in small and medium-sized manufacturing companies are limited due to a lack of statistical knowledge required for their effective implementation. Although many books have been written in this subject, they are mainly by statisticians, for statisticians and not appropriate for engineers.Design of Experiments for Engineers and Scientists overcomes the problem of statistics by taking a unique approach using graphical tools. The same outcomes and conclusions are reached as by those using statistical methods and readers will find the concepts in this book both familiar and easy to understand. The book treats Planning, Communication, Engineering, Teamwork and Statistical Skills in separate chapters and then combines these skills through the use of many industrial case studies. Design of Experiments forms part of the suite of tools used in Six Sigma.Key features: Provides essential DOE techniques for process improvement initiatives Introduces simple graphical techniques as an alternative to advanced statistical methodsâ reducing time taken to design and develop prototypes, reducing time to reach the market Case studies place DOE techniques in the context of different industry sectors An excellent resource for the Six Sigma training program This book will be useful to engineers and scientists from all disciplines tackling all kinds of manufacturing, product and process quality problems and will be an ideal resource for students of this topic.Dr Jiju Anthony is Senior Teaching Fellow at the International Manufacturing Unit at Warwick University. He is also a trainer and consultant in DOE and has worked as such for a number of companies including Motorola, Vickers, Procter and Gamble, Nokia, Bosch and a large number of SMEs.
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In the present study, corn fiber polypropylene (PP) composites were fabricated and tested for their mechanical properties. The effect of matrix modification on mechanical properties is investigated. Maleic anhydride grafted polypropylene (MAPP) is added to matrix and the mechanical properties of MAPP corn fiber composites were found to increase considerably compared with those of PP composites. Experiments were conducted using Taguchi L12 orthogonal array considering the two deign parameters viz. weight fraction of the fiber and treatment. The experimental results were analyzed using Taguchi optimization method. Analysis of variance (ANOVA) was carried out to obtain the significant values of tensile strength, flexural strength and impact strength at 95% confidence level.
Article
Composite consisting of polypropylene reinforced with short sisal fibers were prepared by melt-mixing and solution-mixing methods. In the melt-mixing technique. mixing parameters were optimised by varying the mixing time, rotor speed and chamber temperature. A mixing time of 10 min, rotor speed of 50 rpm and a mixing temperature of 170 degrees C were found to be the optimum mixing conditions. Tensile properties of melt-mixed and solution-mixed composites were compared. Under optimum mixing conditions melt-mixed composites showed better tensile properties than those of solution-mixed composites. The influence of fiber length, fiber loading and fiber orientation on the mechanical properties of PP/sisal composites has been evaluated. The fiber breakage and damage during melt-mixing were analysed from fiber-length distribution curves and optical photomicrographs. The effect of chemical treatment on the tensile properties of sisal/PP composites was investigated. Treatments with chemicals such as sodium hydroxide, maleic anhydride, urethane derivative of PPG, and permanganate were carried out to improve the bonding at the fiber/polymer interface. It hits been observed that all the treatments enhanced the tensile properties of the composites considerably, but to varying degrees.
Article
Thin kenaf/polypropylene (PP) composite sheets were manufactured via extrusion. The effects of kenaf and maleated PP (MAPP) proportions, fibre length, PP melt flow index (MFI) and die temperature on tensile, flexural, in-plane and out-of-plane shear properties were analysed by conducting experiments through ‘design of experiments’ methodology. Higher kenaf content and lower die/barrel temperatures resulted in composite sheets with higher average mechanical properties in various modes of testing. Matrix MFI appeared to significantly affect all mechanical properties. It is interesting to note that the properties of the very short-fibre composites produced are comparable to those reinforced with longer discontinuous fibres and long-fibre mats.
Article
In this review, insight into the use of bio-based fibers as composite reinforcement has been addressed. Specifics on the varieties of natural fibers, and the resultant properties from their constituents and hierarchal structures are described. The methods used to enhance the interface of these fibers with a variety of polymer matrices are reviewed. In addition, the influence of textile operations on creating various fiber architectures with resulting reinforcing capabilities, along with the methods in which natural fiber reinforced composites can be processed, are addressed. Finally, discussion of the correlation between structure, processing, and final composite properties are provided.
Article
This paper is an attempt to examine the commercial signficance of an agro-waste “Pineapple Leaf Fibre” (PALF) which is rich in cellulose, relatively inexpensive and has the potential for polymer reinforcement. The quality enhancement of PALF has been tried through different surface modifications like dewaxing, alkali treatment, cyanoethylation and grafting of AN onto dewaxed PALF. The present study investigated the mechanical propeties like tensile, flexural and impact behavior of PALF-reinforced polyester composites as a function of fibre loading and fibre surface modification. The mechanical properties are optimum at a fibre loading of 30 wt%. Among all modifications, 10% AN grafted PALF composite exhibited maximum tensile strength (48.36 MPa) whereas cyanoethylated PALF composite exhibited better flexural and impact strength, i.e., 41% and 27% more than the control (detergent washed composite) respectively. Scanning electron microscopic studies were carried out to understand the fibre-matrix adhesion.
Article
Bio-based composite materials were tested for suitability in roof structure. Structural beams were designed, manufactured and tested, yielding good results. Based on the beam results, large-scale composite structural panels were made. Soy oil-based resin and cellulose fibers, in the form of paper sheets made from recycled cardboard boxes, were successfully used to manufacture the composite structures. This recycled paper was previously tested in composite sheets and structural unit beams and gave the required stiffness and strength required for roof construction. The roof was designed and a 1/3 scale structure was manufactured. Following this 1/3 scale design, two composite panels of 2.59m×1.52 m×0.089m were manufactured to serve as the two sides of a pitched roof connected at the ridge. The depth of the panels and thickness of the composite skin were dictated by the design as a function if the two other dimensions to give the optimum strength and cost result. To test the manufacturing process for a full-depth roof structure, a 1.27 m×0.53m×0.279m panel was successfully manufactured. In the latter structure, a modified VARTM process was used to replace the solid mold surface with a bagging film. This enabled a visual inspection of the resin flow and provided a window for using additional vacuum and injection lines on the normally hidden bottom side. This bagging method was very successful without the need for mold modification or electronic sensors. Issues related to natural fibers composite processing such as moisture inhibition and drying are also discussed in this work.
Article
Nowadays, the world faces unprecedented challenges in social, environmental and economical dimensions, in which the industrial design has showed an important contribution with solutions that provide positive answers regarding these problems. In particular, due to its relevance, the automotive industry confronts a moment of crises, and based on the ecodesign of products it has been transforming the challenges in opportunities. In this context, the use of natural fiber composites, produced in developing countries, have presented several social, environmental and economical advantages to design “green” automotive components. Thus, this work through LCA method demonstrates the possibility to use natural fibers through a case study design which investigates the environmental improvements related to the replacement of glass fibers for natural jute fibers, to produce a structural frontal bonnet of an off-road vehicle (Buggy). Results pointed out the advantages of applying jute fiber composites in Buggy enclosures.
Article
The research focused on enhancing the mechanical properties and thermal stability of bio-composites with natural flours and improving the interfacial adhesion between biodegradable polymer and flour. The tensile and flexural strength of the PLA bio-composites decreased with increasing flour addition. However, a 3% loading of the compatibilizer in the PLA bio-composite increased this strength up to that observed with the 10% loading flour. The degradation temperature of PLA was decreased by the flour but destarched cassava flour had higher thermal stability on account of its higher lignin content than pineapple flour. This means that the PLA bio-composites with destarched cassava flour had higher thermal stability than those with the pineapple flour. In addition, the thermal degradation temperature was increased by adding MAPLA. The compatibilizer improved the crystallinity of PLA, which enhanced the mechanical strength of the PLA bio-composites. As the pineapple flour and destarched cassava flour 30% loading was increased, the HDT of the PLA bio-composites increased from 56.8°C to ~66.3 and 69.7°C, respectively. The thermal aging test showed no reduction in strength of the neat PLA. However, the PLA bio-composites showed a gradual decrease in tensile strength with increasing number of cycles. Moreover, the shrinkage ratio of the neat PLA was 5% of that found with the PLA resin. KeywordsBiodegradable polymer–PLA–Cassava flour–Pineapple flour–Thermal aging
Article
By embedding natural fibres e.g. flax, hemp, ramie, etc. into a biopolymeric matrix made of derivatives from cellulose, starch, lactic acid, etc., new fibre reinforced materials, the so-called biocomposites, were created at the DLR Institute of Structural Mechanics in 1989 and are still being developed.As far as the mechanical properties are concerned, biocomposites are comparable to the well-known glass fibre reinforced compounds. Therefore, the new construction materials are very well suited to be used for anisotropic and specially tailored lightweight structural parts, making use of the DLR knowledge in fibre reinforced technology. Some samples and structures will be shown in the presentation.Whereas traditional compounds consist of very stable components which are very difficult to decompose, biocomposites are made completely from biologically renewable resources. This offers additional possibilities of a convenient removal after the end of the lifetime i.e. biodegration, composting or carbon dioxide neutral combustion. Thus, biocomposites can also meet the steadily increasing environmental demands of legislative authorities.
Article
Effect of mercerization to tensile properties of a ramie fiber was explored. Load application technique during mercerization has been employed in order to improve mechanical properties of the fiber. A chemical treatment apparatus with tensile loading portion for applying monofilaments was newly developed. The ramie fiber was alkali-treated by 15% NaOH solution with applied loads of 0.049 and 0.098 N. The results showed that tensile strength of the treated ramie fiber was improved, 4–18% higher than that of the untreated ramie fiber, while Young’s modulus of the treated fibers decreased. It should be noted that fracture strains of the treated ramie fiber drastically increased to 0.045–0.072, that is, twice to three times higher than those of the untreated ramie fiber. It was considered that such property improvements upon mercerization were correlated with change of morphological and chemical structures in microfibrils of the fiber. Finally, the plastic deformation behavior and fracture mechanism of the mercerized fibers under tensile loading process was explained using a schematic model.
Article
Natural fibres, such as sisal, flax and jute, possess good reinforcing capability when properly compounded with polymers. These fibres are relatively inexpensive, originate from renewable resources and possess favourable values of specific strength and specific modulus. Thermoplastic polymers have a shorter cycle time as well as reprocessability despite problems with high viscosities and poor fibre wetting. The renewability of natural fibres and the recyclability of thermoplastic polymers provide an attractive eco-friendly quality to the resulting natural fibre-reinforced thermoplastic composite materials. Common methods for manufacturing natural fibre-reinforced thermoplastic composites, injection moulding and extrusion, tend to degrade the fibres during processing. Development of a simple manufacturing technique for sisal fibre-reinforced polypropylene composites, that minimises fibre degradation and can be used in developing countries, is the main objective of this study. Composite sheets with a fibre length greater than 10 mm and a fibre mass fraction in the range 15% to 35% exhibited good mechanical properties.
Article
Surface modifications of two varieties of jute fabrics, i.e. hessian cloth (HC) and carpet backing cloth (CBC), involving dewaxing, alkali treatment, cyanoethylation and grafting, have been made with a view to their use as reinforcing agents in composites based on a biodegradable polymeric matrix, Biopol. The chemically treated fabrics are characterized by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The effects of different fibre surface treatments and amounts of fabrics on the performance of the resulting composites are investigated. Mechanical properties such as tensile strength, bending strength and impact strength increase in comparison to pure Biopol as a result of reinforcement with jute fabrics. More than 50% enhancement in tensile strength, 30% in bending strength and 90% in impact strength of the composites relative to pure Biopol sheets have been observed under the present experimental conditions. Scanning electron microscopy (SEM) investigations show that surface modifications improve the fibre/matrix adhesion. From degradation studies we find that after 150 days of compost burial more than 50% weight loss of the jute/Biopol composite occurs.
Article
The natural fiber/poly(lactic acid) (PLA) composites were prepared with ramie and jute short fiber as reinforcement and PLA as matrix. The mechanical and thermal properties of the composites were investigated. The results show that the properties of the composites are better than those of plain PLA. When the content of the fiber is 30%, the composites can get the best mechanical properties. The dynamic mechanical analysis results show that the storage moduli of the PLA/ramie and PLA/jute composites increase with respect to the plain PLA. The Vicat softening temperature of the composites is greatly higher than that of PLA. The results of thermogravimetric analysis show that adding fiber to the PLA matrix can improve the degradation temperature of PLA.
Article
Vacuum-assisted resin transfer molding or resin vacuum infusion process was used to make composite panels out of plant oil-based resin [acrylated epoxidized soybean oil (AESO)] and natural fiber mats made of flax, cellulose, pulp and hemp. The composites formed by room temperature cure with natural fiber reinforcement of about 10–50 wt% increased the flexural modulus to a range between 1.5 and 6 GPa depending on the nature of the fiber mat. The AESO resin reinforced with woven E-glass fiber was tested as a reference and gave a flexural modulus of 17 GPa, while a room temperature curing of the neat resin gave a flexural modulus of about 1.1 GPa. Recycled paper was used as a cheap resource of cellulose fiber and found to work well with AESO resin in terms of flow, impregnation, and surface bonding, giving a modulus of over five times that of the neat resin. These low-cost natural composites were found to have mechanical strength and properties suitable for applications in housing construction materials, furniture and automotive parts.
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