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Wood–Textile Composites (WTCs) are a new type of composite material based on willow wood strips and polypropylene that combines the properties of classic natural-fiber-reinforced polymers with an innovative textile wood design. While the basic quasi-static properties have already been investigated and described, there is a lack of knowledge about the behavior of the material under dynamic-cyclic and dynamic-impact loading as well as in relation to basic wood construction parameters. The present study is intended to contribute to the later use of the developed material, e.g., in architecture. For this purpose, fatigue tests, dart drop tests (impact and penetration), impact bending tests, and embedment tests were carried out. It was shown that embedding wood fabrics in a thermoplastic matrix leads to a significant increase in resistance to impact loads compared to the neat basic materials. It was also shown that the ratio of the failure stress in the fatigue test to the tensile strength of the WTC corresponds to that of other fiber-reinforced thermoplastics at around 70%. The embedment tests showed that WTC has good values compared to neat wood. [ABSTRACT FROM AUTHOR]

In recent decades, natural fiber reinforced composites (NFRCs) have become an attractive substitute for conventional materials such as glass fiber and have attracted considerable interest from researchers and academics, particularly in the context of environmental protection. Environmental factors and their impact on the fundamental properties of renewable materials are becoming an increasingly popular area of study, particularly natural fibers and their composites. While this area of research is still expanding, natural fiber-reinforced polymer composites (NFRCs) have found widespread use in a variety of engineering contexts. Natural fibers (NFs) such as pineapple leaf (PALF), bamboo, abaca, coconut fibers, jute, banana, flax, hemp, sisal, kenaf, and others have many desirable properties, but their development and use present researchers with a number of obstacles. These fibers have attracted attention due to their various advantageous properties, such as lightness, economy, biodegradability, remarkable specific strength, and competitive mechanical properties, which make them promising candidates for use as biomaterials. As a result, they can serve as alternative materials to traditional composite fibers such as glass, aramid, and carbon in various applications. In addition, natural fibers have attracted the interest of an increasing number of researchers because they are readily available in nature and as by-products of agricultural and food systems, contributing to the improvement of the environmental ecosystem. This interest coincides with the search for environmentally friendly materials to replace synthetic fibers used in the construction, automotive, and packaging industries. The use of natural fibers is not only logical but also practical, as their fibrous form can be easily extracted and strengthened by chemical, physical, or enzymatic treatments. This article provides a brief overview of NFRCs, looking at their chemical, physical, and mechanical properties. It also highlights some of the significant advances associated with NFRCs from an economic, environmental, and sustainability perspective. Additionally, it provides a concise discussion of their diverse applications, all with a focus on their positive impact on the environment. [ABSTRACT FROM AUTHOR]

Wood Textile Composites (WTCs) represent a new and innovative class of materials in the field of natural fiber composites. Consisting of fabrics made from willow wood strips (Salix americana) and polypropylene (PP), this material appears to be particularly suitable for structural applications in lightweight construction. Since the threads of the fabric are significantly oversized compared to classic carbon or glass rovings, fundamental knowledge of the mechanical properties of the material is required. The aim of this study was to investigate whether WTCs exhibit classic behavior in terms of fiber composite theory and to classify them in relation to comparable composite materials. It was shown that WTCs meet all the necessary conditions for fiber-reinforced composites in tensile, bending, and compression tests and can be classified as natural-fiber-reinforced polypropylene composites. In addition, it was investigated whether delamination between the fiber and matrix can be simulated by using experimentally determined mechanical data as input. Using finite element analysis (FEA), it was shown that the shear stress components of a stress tensor in the area of the interface between the fiber and matrix are responsible for delamination in the composite material. It was also shown that the resistance to shear stress depends on the geometric conditions of the reinforcing fabric. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced composites (NFRCs) are expected to find growing applications in near future, especially in Europe where stringent environmental codes are being legislated and public pressure for their enforcement is increasing. Study has shown that NFRCs are also gaining recognition among civil engineers as a viable alternative to traditional materials for use as concrete reinforcement in load-bearing structural members as in building frames and bridge decks. The present review strives to provide a brief overview of NFRCs, state-of-the-art developments in their manufacture, and examples of their structural applications. Another aspect of the review involves investigation of the challenges facing the use of fiber composite materials in civil engineering. These include the high manufacturing costs, difficulties associated with appraisal of its potential benefits, uncertainties about their properties, lack of understanding among civil engineers of the material and its service life, and the relatively small battery of standards developed for the composite industry. Finally, the study will conclude with the prospects of bio-composite applications and the emerging trends in novel bio-composites for future structural applications. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the efficiency of a hybrid patch of Jute with/without Glass fiber reinforced with Steel wire for repairing defective API X52 pipeline. Five specimens were tested using Jute fiber, Glass fiber and Steel wire to enhance the mechanical properties according to ASTM 3039 and D790 standards. The experimental results showed that the effects of hybrid materials (synthetic and natural) for repairing API X52 pipeline defect depend on the nature of the patch and the properties of the adhesive (polyester resin) by increasing the tensile strength and bending load. In the first step, specimen S5 was selected due to its distinctive mechanical properties, which revealed maximum values of tensile strength, toughness and bending load respectively 47,42014 MPa, 2357,42 kJ m−3 and 488,3 N. In the second step, the selected sample (S5) was used as a patch to repair API X52 pipeline, which has semi-elliptical defects where the bending load is 31.4246 kN. According to the obtained results, the patch efficiency is 103 % for defects with a/t < (0,3), which can be, restored 100 % of the mechanical properties. Therefore, repairing API X52 pipeline using hybrid patch (Jute reinforced with Steel wires) with shallower defects can be a successful technique. • Experimental study is performed to appear the efficiency of hybrid patch in hydrocarbons field. • We found that using the hybrid patch with different layers reinforced by wires metal is significantly positive on the safety of semi-elliptical defected of the API X52 pipelines corroded according to ratio a/t. • High performing of hybrid patch (Jute fibers reinforced by wires metal) were confirmed for the defect sizes of the ratio a/t less than 0.3 (a/t < 0.3). • The natural fibers have the capability to replace synthetic fiber due to its positives features such as recycling and environment friendly. • The obtained results show that hybridization with metal wires and the number of stacking improved properties of the composite materials. [ABSTRACT FROM AUTHOR]

Lignocellulosic natural fibers remain at the forefront of eco-friendly and sustainable reinforcement materials in composites. This work addresses the inherent limitations of lignocellulosic fibers in terms of their hydrophilicity and incompatibility to achieve maximum utilization in most commercial resins using a reversible addition-fragmentation chain transfer radiation-induced graft polymerization (RAFT-RIGP) approach. The one-pot surface modification technique via RAFT-RIGP was shown to efficiently graft poly(glycidyl methacrylate) onto lignocellulosic fibers like abaca. Results from the analyses of the different grafting parameters and polymerization trends reveal that the employed RAFT-mediation improved grafting yield compared to a conventional RIGP despite retardation effects inherent in the RAFT mechanism. Additionally, sufficient control over the molecular weight and dispersity of grafted chains was exhibited. The modified fibers showed improved tensile strength, higher thermal stability and reduced moisture uptake. Overall, we have demonstrated that RAFT-RIGP can be a facile, environment-friendly technique for the surface compatibilization of lignocellulose fibers without the mechanical deterioration of substrate properties, unlike other fiber modification processes. Therefore, this method has a great potential in natural fiber compatibilization for reinforcement in polymer composites. [ABSTRACT FROM AUTHOR]

In this study, composite materials were made from Carica papaya fibers (CPFs), as a reinforcing element in polypropylene (PP), polyester (P) and epoxy (E) matrices, using compression molding technique. Experiments were conducted to evaluate the input parameters with their output responses, specifically density and thickness. Various CPF reinforced PP, P, and E composite specimens with varied fiber orientations of 0°, 45°, and 90° as well as percentages of fiber contents of 10, 20, and 30 wt.% were prepared, according to the ASTM D 570 standard. From the results obtained, it was observed that CPF/E composites with fewer fraction of CPF and orientation of 90° exhibited less water absorption throughout the whole duration of immersion. Water saturated CPF/E composite specimen, designated as E8, with orientation of 0° and fiber content of 20 wt.% showed the highest tensile, flexural strengths, and Shore D Hardness of 119, 115 MPa, and 85, respectively. Also, CPF/E composite specimen (E7) with 90° and 10 wt.% recorded the lowest tensile strength of 32 MPa, and CPF/E composite (E3) with 90° and 30 wt.% showed the lowest flexural strength of 41 MPa. Hence, it was evident that optimum CPF reinforced polymeric composite can be used for some outdoor engineering applications. [ABSTRACT FROM AUTHOR]

• Exploring the novel hybrid joints in natural fiber based composite materials. • Comparing the various mechanical, fusion and hybrid joining techniques in flax/PP composites. • Investigating the influence of number of bolts and bolt diameter on performance of various joints in flax/PP composites. • Investigating of effect of fusion bonding on the crystallinity and thermal decomposition behaviour of flax/PP composites. The current research endeavour reports the performance of single shear lap joints of flax/PP composite laminates. The joints were fabricated using mechanical joining, fusion bonding (ultrasonic and hot plate joining), and hybrid joining techniques (mechanical/ultrasonic joining and mechanical/hot plate joining). In case of the mechanical and hybrid joining, the effect of the bolt size, and number of bolts (single and double) on the tensile failure load was investigated. Pertaining to mechanical joining, the large bolt size and double bolts recorded higher tensile failure load compared to smaller bolt size and single bolt, respectively. Whereas with double bolts, no increase in the tensile failure load was observed for the hybrid joints, due to reduction in bonded area. The hybrid joints (mechanical/ultrasonic) recorded the maximum tensile failure load compared to all other type of joints. The load-extension behaviour and failure of joints was also examined. Expect mechanical joints, all other joints exhibited structural type of failure. In contrast, the mechanical joints resulted in a net-tension failure mode with failure line passing through the hole. However, the thermal decomposition and crystalline behaviour (XRD spectra) of developed joints did not vary significantly. The morphology of failed joints was examined using scanning electron microscope. [ABSTRACT FROM AUTHOR]

The usage area of natural fiber reinforced composite materials has been increasing day by day, due to their attaining to not only ecological benefits but also high mechanical properties with their low weight. After the fabrication of natural fiber reinforced composites, they need to be subjected to secondary processes such as milling, drilling and turning processes according to their field of use. In this study, it was aimed to determine milling performance of JFRP and FFRP composites, which are obtained from natural fibers. Experiments were carried out at the different processing parameters. The effects of these parameters on cutting force, vibration amplitude, delamination factor, and surface roughness were investigated. Vibration amplitude and delamination factor increased, and cutting force and surface roughness decreased with increasing spindle speed. Cutting force, vibration amplitude, delamination factor and surface roughness increased with increasing feed rate. The most appropriate values for cutting force, delamination factor and surface roughness were obtained in experiments where WC end mill was used. However, in vibration amplitude, the lowest values were HSS end mill. Delamination factors and surface roughness in FFRP composites were higher than those of JFRP composites. Cutting forces of FFRP composites were lower than those of JFRP composites. [ABSTRACT FROM AUTHOR]

In automobile and aerospace applications, composite materials play a vital role due to their weight reduction and competitive cost. Fiber reinforced polymer (FRP) nanocomposites are suitable for such applications. Screw pine fiber is another more advanced and promising natural fiber used in the form of discontinuous fibers as reinforcement material. Three different volumetric proportions - 3 mm, 6 mm and 9 mm - of screw pine reinforced polyester composite are studied. The most economical hand-lay method is utilized to fabricate the screw pine FRP nanocomposites. The aim of production is to enhance toughness, dimensional stability, stiffness and strength by embedding particles such as fibers in a matrix. The mechanical properties are analyzed for 10 %, 20 %, 30 % and 40 % of fiber loading with various fiber lengths 3 mm, 6 mm and 9 mm. Nanofiber content of 30 % with 9 mm displayed maximum strength of impact, flexural strength, tensile strength and strong elasticity module. [ABSTRACT FROM AUTHOR]

This paper aims to develop a 2D finite element (FE) model at microscale for numerical simulation of the machining behavior of natural fiber-reinforced polymer (NFRP) composites. The main objective of this study is to reproduce the experimentally observed specific cutting behavior of natural fibers within the composite material. Flax fiber-reinforced polypropylene (PP) composites are modeled separately using an elasto-plastic behavior with a ductile damage criterion for flax fibers and PP matrix, while the microscopic interfaces are represented using the cohesive zone modeling (CZM). Numerical outputs are compared with experimental results for the FE model validation. Results show that the proposed FE model can reproduce the cutting force with a good precision for a large cutting speed range (12–80 m/min). The FE model shows also an efficiency and accuracy in predicting the cutting behavior of flax fibers by reproducing the fiber deformation, the fibers torn-off, and the fracture of the interfaces during machining. Moreover, the FE model can be an effective tool for analyzing the quality of the microscopic interfaces in the NFRP composites after machining. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced polymer composites are attracting researchers' attention as environmentally friendly and sustainable materials because of their low environmental load imposed by manufacture and disposal. Natural fiber-reinforced composites have comparable or somewhat inferior mechanical performance when compared to glass fiber-reinforced plastics (GFRP), but have some unique characteristics, which include low thermal conductivity, biodegradation in natural environments and effective suppression of vibration. This paper presents a review of the typical functionalities of natural fiber-reinforced composites including thermal insulation property, biodegradable property and vibration damping property. As described herein, the author will introduce each functionality and discuss the effects of many factors affecting the performance of each function. Consequently, this paper reports that composite materials that fully use their functionality rather than mechanical performance are important for the future development of natural fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

This work is focused on the study of mechanical and physicochemical properties of an innovative and environmentally friendly composite material based on different sugar palm fiber (SPF) loadings (10–30 wt %) with thermoplastic polyurethane (TPU). A two-step technique was used (extrusion of TPU with SPF fibers at 190°C; rotational velocity of 40 rpm, followed by hot press 190°C for 10 min) to obtain the composites. The size of SPF was fixed at 250 µm, and different weight percentages (10, 20, and 30 wt %) of SPF were added in TPU to find the optimum composition. The mechanical (impact, tensile, and flexural) properties of the new (TPU/SPF) composite were studied as per ASTM standards. The Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and the X-ray Diffraction (XRD) were employed for structure and morphology study of TPU/SPF composites. The results proved that best tensile strength (14 MPa) and strain performance is shown with 10 wt %, while at 20 wt % exhibited maximum impact property. An increasing trend was recorded in flexural properties and tensile modulus with the increasing fiber loading. On the other hand, strain deteriorated with increment of fiber content. [ABSTRACT FROM AUTHOR]

[Display omitted] • Weakly hydrogen bonded water migrate from cellulose under dry preparation can fully plasticize the polyvinyl alcohol. • Cellulose and polyvinyl alcohol form hydrogen bonding at the interface layer. • Water molecules migrate to the free volume of the cellulose/PVA interface forming stable bridging hydrogen bond. • Water in the plant fiber has an important role in plant fiber/PVA composite materials prepared by dry preparation method. The preparation of a composite material based on plant fiber that contains water and polyvinyl alcohol (PVA) powder was analyzed by molecular dynamic simulations. The results show that water migration from cellulose under specific temperature and pressure conditions is influenced by its hydrogen bonding with different components. Water strongly hydrogen bonded to plant fiber migrates with difficulty, whereas weakly hydrogen bonded water migrates to the interfacial layer to form stable hydrogen bonded bridges. Water molecules not captured by the interfacial layer migrate to the PVA phase and form new hydrogen bonds that have a plasticizing effect for PVA. The plasticized PVA can better coat the plant fiber, forming more hydrogen bonds between PVA and plant fiber. Hydrogen bonding bridges formed by water at the interface strengthen the interfacial bonding. Simulation and experimental results show that PVA with a lower molecular weight has stronger interfacial binding strength with the plant fiber, giving a higher modulus. The appropriate plant fiber water content achieves the optimal composite mechanical properties. Water has a significant role in the interfacial enhancement of plant fiber/PVA composite materials prepared by the dry preparation method. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the tribo-mechanical behavior of natural fiber reinforced plastic (NFRP) composites with specific consideration of the multiscale complex structure of natural fibers. Understanding the multiscale tribo-mechanical performances of these eco-friendly materials can lead to a better design of their manufacturing processes. Nanoindentation and nanoscratching experiments are conducted on flax fibers reinforced polypropylene composites using a triboindenter at a specific contact scale generated by the tip indenter radius (100 nm). Results confirm the significant effect of the geometric contact scale on the flax fibers stiffness. Moreover, flax fibers friction shows a multiscale behavior where the mechanisms of nano-friction are vastly different from those of micro-friction, which is related to the physical phenomena arisen at each scale. [ABSTRACT FROM AUTHOR]

Natural fibers are lighter, less expensive, and less abrasive than synthetic fibers such as glass or carbon, and provide a resource that is both renewable and biodegradable. This study uses surface treatments and flock fiber based Z -axis reinforcement technology to improve the strength and fracture toughness properties of natural fiber composites (NFCs), thus increasing their ability to bear loads. The enhancement of performance properties will expand applications of NFCs in industries such as automotive and housing/construction industries. NFCs will also provide a more sustainable, environmentally friendly, and inexpensive structural material alternative over traditional resin reinforced glass or carbon fiber composite materials. [ABSTRACT FROM AUTHOR]

The objective of this work is to infuse nanoclay particles into the banana fiber and study the morphological and structural characteristics. Nanoclays were infused into the fibers by shear induced force with the aid of alkaline (NaOH) chemical treatment. About 6 wt.% of nanoclays were infused into the banana fibers by this method. The short banana fiber reinforced epoxy composites were prepared by resin casting method in which the critical length (lc) and critical volume fraction (Vfc) of the fibers were determined. The nanoclay infused fibers were compared with untreated and alkaline treated fibers. The result suggests a positive effect on tensile, interfacial, and thermal properties of fibers due to nanoclay infusion. The tensile, shear, and dynamic mechanical analysis (DMA) of composites were studied, and the result shows superior improvement of these properties in nanoclay infused fiber composites. [ABSTRACT FROM AUTHOR]

Conventional materials selection system was replaced with sophisticated software tools by rapid changing technology. The growing environmental concerns and regulations widely among the industry, especially in automobiles, force us to explore the natural fiber materials as a replacement for synthetic materials which is in common use. As a result of extensive research and development, new natural fiber reinforced composite materials are emerging and the database of materials growing exponentially. The decision of selecting optimized materials was complicated, as it involves diversified choice of materials, coupled with various influencing criteria for the selection process. To abstain from deciding inappropriate materials, the technology of expert system software tools can help us in the appropriate materials selection. The objective of this research was to explore the implementation of Analytical Hierarchy Process (AHP) using the expert choice software tool for deciding optimum natural fiber reinforced composite materials by considering main criteria and sub-criteria in the hierarchical model. The final judgement was performed with different scenarios of sensitivity analysis, giving priority to the environmental factors and sustainability. The result shows that the natural fiber composite material hemp and polypropylene gained the higher rank in the selection process and almost compliant with the requirements of industrial product design specification and can be recommended to automotive component manufacturers to enforce green technology. [ABSTRACT FROM AUTHOR]

The present paper investigates the acoustic properties of natural fiber reinforced composites. Fibers from orange tree pruning were obtained and subject to different treatments in order to obtain mechanical, thermomechanical and chemi-thermomechanical pulps. These pulps were used as reinforcement for a polypropylene matrix. The obtained composite materials were submitted to acoustical tests in an impedance tubes device. The transmission losses obtained against the fiber content were obtained and discussed. Latter it was researched the influence of the fiber treatments on the soundproof characteristics. A numerical method was used to preview the acoustic insulation of the materials against the sound frequency. Finally the results were compared with that of the most usual lightweight soundproof solutions. [ABSTRACT FROM AUTHOR]

Modeling the infiltration of reinforcements during the processing of composite materials by liquid composite molding techniques is an important instrument for the prediction of flow front patterns, filling times and pressure gradients. Darcy’s law is widely used to model most of these processes. However, when polar fluids are used together with natural fibers, fiber swelling may occur and introduce further complexity to the simulation. In this work, a model that includes the aforementioned phenomena is proposed, leading to a more accurate prediction of the flow front position than the classic models that use a constant permeability value. [ABSTRACT FROM AUTHOR]

The present work, is focused on the study of beam type structures made of agro waste composite materials, namely of sawdust and palm kernel shell, and comprises two parts. A first one where the static and dynamic behavior characterization of the structure is carried out using a first order shear deformation theory approach, considering the influence of different fiber constituent's percentages. In the second part, a few structural optimization case studies are considered concerning different objective functions and constraints, using sequential quadratic programming technique. Both, analysis and optimization studies were developed on a symbolic computation platform. According to the results obtained in the case studies carried out, it can be concluded that they respect the trends that would be expected, taking into account the nature of the parameters studied: the length to thickness ratio, the boundary conditions and the percentages of the reinforcement agents' mixtures. A final aspect that is worth mentioning is related to the advantages of using such type of platform in research work, which enables for an integrated development and simulation environment, where the libraries access and the functionalities available, enable a more expedite and perceptive way of achieving results. [ABSTRACT FROM AUTHOR]

Treated and untreated woven century fiber (CF) composites are investigated for evaluating their flexural, tensile, and impact strengths, Barcol hardness, glass transition temperature, thermal resistance, and water absorption properties. Scanning electron microscopy study revealed a brittle fracture for treated fiber composite, while significant fiber pull-out is observed for the untreated fiber composite. Higher tensile and hardness properties, higher glass transition and thermal decomposition temperatures, and low water absorption properties are obtained for alkaline-treated composites. Enhanced interface bonding due to improved adhesion has helped in the formation of covalent bonds at the fiber–matrix interface, resulting in superior tensile, thermal, and water absorption properties of the treated fiber composite. Flexural and impact properties are higher for untreated fiber composite. This is due to the weak fiber–matrix interface and a differential strain in fiber and matrix. The weak interface has provided an energy absorbing mechanism and enhanced the impact energy absorption capacity. The tensile strength of CF composite is very much comparable with that of sisal fiber composite. The tensile and flexural properties are higher for the woven CF composites than those of short CF composites. But the impact properties are superior for short fiber composites compared to the woven fiber composites. Increased number of interfaces for the short fiber composites has contributed for the cushioning effect and an enhanced energy absorbing mechanism. Water absorption properties have improved for the treated fiber composites due to formation of a strong interface. [ABSTRACT FROM AUTHOR]

The effect of aminosilane on the properties of rice straw fiber (RSF) reinforced poly(butylene succinate) (PBS) composites was studied. RSF was pretreated with four different aminosilane coupling agents, 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMES), 3-(2-aminoethylaminopropyl)triethoxysilane (AEAPTES), and 3-(2-aminoethylaminopropyl)-trimethoxysilane (AEAPTMES). The results of Fourier transform infrared spectroscopy (FTIR) and ζ potential measurements confirmed that amino groups were introduced to the silane-treated RSF (TRSF) for all four silane coupling agents. The results also indicated a higher degree of hydroxyl ion adsorption by the fiber surface, which was chemically grafted by silane hydroxyl, was obtained with ethoxy silane than with methoxy silane. This difference might be because the relative rates of hydrolysis and ensuing silanol self-condensation of methoxy silane were too fast to reduce the number of silanol groups grafted on the fiber surface. The TRSF composite produced clearly enhanced tensile properties for the aminosilane coupling agents having ethoxy groups. The AEAPTES-RSF-PBS composite showed the highest tensile strength. It might be because of the higher amino content of AEAPTES than APTES; the amino groups on the surface of TRSF were confirmed by FT-IR to react with the carbonyl groups of PBS to form a blue-shifted hydrogen bond. The water absorption process of composites was found to follow the kinetics and mechanisms described by Fick's theory. The aminosilane treatment significantly reduced the moisture diffusion coefficient but did not change the mechanism of water adsorption. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The use of hemp fibers as reinforcement in composite materials has increased in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materials. Hemp fibers are found in the stem of the plant which makes them strong and stiff, a primary requirement for the reinforcement of composite materials. Themechanical properties of hemp fibers are comparable to those of glass fibers. However their biggest disadvantage is the variability in their properties. Composites made of hemp fibers with thermoplastic, thermoset, and biodegradable matrices have exhibited good mechanical properties. A number of hemp fiber surface treatments, used to improve the fiber/matrix interfacial bonding, have resulted in considerable improvements in the composites’ mechanical properties. [ABSTRACT FROM AUTHOR]

A composite of themoplastic polyurethane (TPU) reinforced with short kenaf (Hibiscus Cannabinus L.) fiber (KF) was prepared by a melt-mixing method. Mixing was followed by compression molding to produce sheets for specimen cutting. Five samples were cut from the composite sheet. A mean value was taken for each sample according to ASTM standards. The aims of this study were to optimize the processing parameters and fiber size of TPU/KF composite. The method used to develop this composite consisted of two main steps. First, the influence of processing parameters such as temperature, time, and speed on tensile properties was studied. Second, effects of different fiber size on tensile properties, flexural properties, and impact strength were tested. The optimum blending parameters were 190°C, 11 min, and 40 rpm for temperature, time and speed, respectively. TPU/KF composites with different fiber sizes were prepared, namely, <125, 125-300, and 300-425 µm. Tensile and flexural strength and modulus were best for fiber size range between 125 and 300 µm. Impact strength showed a slight increasing trend with an increase in fiber size. [ABSTRACT FROM AUTHOR]

Pulverized oil palm fruit bunch (OPFB) fiber was used as filler in Polypropylene (PP). Pulverized OPFB was added at various sizes (250 μm, 180 μm, 125 μm, and 100 μm) to study its effect on the physical and mechanical properties of OPFB filled PP. OPFB powder was mixed with polypropylene at 20 wt% and maleic anhydride polypropylene (MAPP) was also added as coupling agent at 2 wt%. Water absorption behavior of composites followed the normal trend where the water uptake increases with the increasing of OPFB size due to its hydrophilic characteristic. The incorporation of OPFB also decreases the thermal stability of composites at initial stage. Tensile and flexural properties were enhanced with the addition of OPFB powder and further increased with the increase of OPFB size. Meanwhile elongation at break and impact strength were decreased with the increase of OPFB size. SEM observation on the fracture surface of tensile, flexural, and impact tested samples provide further understanding on the effect of OPFB as filler in the matrix. [ABSTRACT FROM PUBLISHER]

In this study, the effects of material optimization and compounding processes on the properties of natural fiber composites were studied. The thermal stabilities of sisal fiber and jute fiber were compared by thermogravimetric analysis. The influences of fiber content, coupling agent, fiber geometry, and fiber distribution on the properties were also researched. It was observed that sisal fiber had more thermal stability than jute fiber. Addition of coupling agent, long fiber length, and uniform fiber distribution led to higher performance composites. For the sisal fiber-reinforced polypropylene composites, the critical fiber length was 2.27mm and the interfacial shear strength was 22.03MPa with MAPP. The tensile strength of composites was also theoretically predicted based on Kelly--Tyson model. [ABSTRACT FROM AUTHOR]

Hemp fiber is one of the inexpensive and readily available bast natural fibers and hemp-fiber reinforced polymer composite products have gained considerable attraction for automotive interior products. Though extensive research has been made on the performance evaluation of these composite materials, not much data is available on the moisture absorption of the composites, which restricts their use in exterior applications. This study aims to investigate the moisture absorption of short hemp fiber and hemp-glass hybrid reinforced thermoplastic composites to study their suitability in outdoor applications. The water absorption properties and its effect on the tensile properties of hemp and hemp/glass fiber hybrid polypropylene (PP) composites prepared by an injection molding process were investigated. Effect of hybridization on the water uptake and the kinetics of moisture absorption of the hemp fiber composites were evaluated by immersing the hybrid composite samples in distilled water at different temperatures, of 40, 60 and 80°C. The composites showed a Fickian mode of diffusion; however, a deviation was observed at higher temperature and may be attributed to the microcraks developed at the interface and dissolution of the lower molecular weight substances from the natural fibers. Equilibrium moisture content (Mm) showed that water up take of 40wt% hemp fiber reinforced PP composites was highest and incorporation of glass fiber decreased the water uptake significantly (40%). Equilibrium moisture content was found to be independent of temperature, while diffusion coefficient (D) was increased with temperature. Effect of water absorption on the tensile properties of the composites showed that there is a significant reduction in strength and stiffness. It was observed that hybridization with glass fibers did not have any significant effect on the strength properties of the aged samples. The tensile properties of the re-dried aged samples showed an increased retention of strength properties after drying; however a complete recovery of the properties has not been achieved. This indicated that water absorption is not a physical process and permanent damage occurred to the composite after aging. [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate the effect of the alkali treatment on the mechanical properties of jute fibers and its composites. The effect on the processing conditions was also analyzed. Woven jute preforms were used to prepare the composites using the vacuum infusion technique. The fibers were treated with NaOH (5 wt.%) for 24 h at room temperature. Single filament tests showed that the treatment was detrimental for the mechanical properties of the fibers. The injection times increased in the treated jute preforms as a consequence of the increase in the exposed area and the flow resistance. The preform permeability decreased, also, in the tubular structure collapse of the fibers, which could reduce the capillary pressure. Flexural and impact properties of the treated jute composites decreased mainly in the lower mechanical properties of the fibers. [ABSTRACT FROM AUTHOR]

Environmentally friendly composite materials can be prepared using wood fibers and/or various types of agro-derived fibers as reinforcements. In this study, agro-residues such as wheat straw and corn stem filled polypropylene were prepared and their suitability was investigated as a reinforcing filler in thermoplastics and as an alternative to the wood flour filled plastics. Effect of compounding techniques, compatibilizer and fungal treatment of agro-residues on the mechanical properties of the composites were evaluated. It was found that high shear compounding of wheat straw fibers exhibited similar properties to that produced by the milled wheat straw. This may be due to the extensive fiber breakage occurred during the high shear compounding that results in a similar aspect ratio to that of milled straw. Compatibilizer is needed for improving the strength properties of the agro-residue filled PP composites. Fungal treatment of milled wheat straw did not show much improvement in the strength properties of the composites. Comparison of mechanical properties of the agro-residue filled PP with that of the wood flour and the old newsprint filled PP showed the suitability of the agro-residues as alternative filler for thermoplastics. [ABSTRACT FROM AUTHOR]

Throughout the world there have been alarming concerns over the use of nonrenewable resources during manufacturing of goods and associated environmental legislations. Therefore, the use of natural materials and fabrication of composites therefrom, particularly, development of natural fiber reinforced polymer composites is gaining significant attention. Although natural fiber reinforced composites (NFRCs) show strong application prospects, various materials and processing related challenges needs to be addressed to achieve long-term stability and performance. In this review, we attempted to provide an overview of different types of natural fibers, their characteristics and properties enabling them to be used as reinforcing agents in different polymers. Then the unique requirement of fiber surface modification to achieve enhanced fiber-matrix bonding is discussed. The article also discusses conventional processing routes and critical issues associated with NFRCs processing. The use of different additive manufacturing (AM) technologies in processing polymer composites is also discussed. At the end, we have critically analyzed the challenges and opportunities associated with AM of NFRCs. [ABSTRACT FROM AUTHOR]