Showing papers on "Natural fiber published in 2007"
TL;DR: In this article, different chemical modifications on natural fibers for use in natural fiber-reinforced composites are reviewed, including alkali, silane, acetylation, benzoylation, acrylation, maleated coupling agents and permanganate.
Abstract: Studies on the use of natural fibers as replacement to man-made fiber in fiber-reinforced composites have increased and opened up further industrial possibilities. Natural fibers have the advantages of low density, low cost, and biodegradability. However, the main disadvantages of natural fibers in composites are the poor compatibility between fiber and matrix and the relative high moisture sorption. Therefore, chemical treatments are considered in modifying the fiber surface properties. In this paper, the different chemical modifications on natural fibers for use in natural fiber-reinforced composites are reviewed. Chemical treatments including alkali, silane, acetylation, benzoylation, acrylation, maleated coupling agents, isocyanates, permanganate and others are discussed. The chemical treatment of fiber aimed at improving the adhesion between the fiber surface and the polymer matrix may not only modify the fiber surface but also increase fiber strength. Water absorption of composites is reduced and their mechanical properties are improved.
2,286 citations
TL;DR: In this article, pulp fibers were fibrillated uniformly into nano-sized fibers using a grinder with a specially designed set of grinding disks, and the effect of the fibrillation through the grinder on the physical properties of the composites was investigated.
Abstract: Pulp fibers were fibrillated uniformly into nano-sized fibers using a grinder with a specially designed set of grinding disks. To investigate the effect of the fibrillation through the grinder on the physical properties of the composites, dissolved pulp fibers were subjected to various passes through the grinder, and the resulting fibrillated pulp fibers were used to make fibrillated pulp fibers/acrylic resin composites. Scanning electron microscopy observations showed that at above five passes, the structure of the fibrillated pulp fibers did not change significantly. The light transmittances of the composites were increased to 80% up to five passes through the grinder, and did not change after further passes. However, the tensile test and thermal expansion analysis indicated that a degradation of the fibrillated pulp occurred during the grinding treatment. To evaluate the fiber degradation, the degree of crystallinity and degree of polymerization of cellulose were measured. Both decreased as the number of passes through the grinder increased. In addition, to reduce the thermal expansion of composites, the fibrillated pulp fibers were additionally treated by sulfuric acid. The thermal expansion of composites was decreased, because the amorphous region of cellulose was removed.
612 citations
TL;DR: In this paper, composites based on cellulose fibres (raw or chemically modified) as reinforcing elements and thermoplastic matrices were prepared and characterized, in terms of mechanical performances, thermal properties and water absorbance behaviour.
594 citations
TL;DR: In this paper, kenaf bast fibers, supplied by MARDI, for use in fiber-reinforced composites, were modified using NaOH of different concentrations, and a series of fiber bundle tensile tests were also performed to evaluate the effect of the treatments on the fiber tensile strength.
496 citations
TL;DR: In this paper, the kenaf-polypropylene natural fiber composites were fabricated using a compression molding process utilizing a layered sifting of a microfine polypropylene powder and chopped Kenaf fibers.
Abstract: As industry attempts to lessen the dependence on petroleum based fuels and products there is an increasing need to investigate more environmentally friendly, sustainable materials to replace existing materials. This study focused on the fabrication of kenaf fiber reinforced polypropylene sheets that could be thermoformed for a wide variety of applications with properties that are comparable to existing synthetic composites. The research done in this study has proven the ability to successfully fabricate kenaf–polypropylene natural fiber composites into sheet form. The optimal fabrication method for these materials was determined to be a compression molding process utilizing a layered sifting of a microfine polypropylene powder and chopped kenaf fibers. A fiber content of both 30% and 40% by weight has been proven to provide adequate reinforcement to increase the strength of the polypropylene powder. The use of a coupling agent, 3% Epolene enabled successful fiber–matrix adhesion. The kenaf–PP composites compression molded in this study proved to have superior tensile and flexural strength when compared to other compression molded natural fiber composites such as other kenaf, sisal, and coir reinforced thermoplastics. With the elastic modulus data from testing, it was also possible to compare the economic benefits of using this kenaf composite over other natural fibers and E-glass. The kenaf–maleated polypropylene composites manufactured in this study have a higher Modulus/Cost and a higher specific modulus than sisal, coir, and even E-glass thereby providing an opportunity for replacing existing materials with a higher strength, lower cost alternative that is environmentally friendly.
439 citations
TL;DR: Baley et al. as discussed by the authors studied the tensile properties of natural fiber-biopolymer composites in order to determine whether or not, biocomposites may replace glass fibre reinforced unsaturated polyester resins.
420 citations
TL;DR: In this paper, the effect of filler concentration on the mechanical properties of wood-fiber filled composites, prepared by using m-TMI-g-PP as the compatibilizer, was investigated.
Abstract: Natural fibers are increasingly being used as reinforcement in commercial thermoplastics due to their low cost, high specific properties and renewable nature. While the maleic anhydride modified polypropylene (MAPP) is most commonly used as compatibilizer to improve interfacial adhesion between hydrophilic wood–fibers and hydrophobic polypropylene, in this study, a novel compatibilizer (m-TMI-g- PP) with isocyanate functional group was synthesized by grafting m-isopropenyl-\alpha,\alpha-dimethylbenzyl-isocyanate (m-TMI) onto isotactic polypropylene (PP) in a twin screw extruder. The effect of filler concentration on the mechanical properties of wood–fiber filled composites, prepared by using m-TMI-g-PP as the compatibilizer, was investigated. The addition of the compatibilizer resulted in greater reinforcement of composites, as indicated by the improvement in mechanical properties. Tensile strength of composites so prepared increased by almost 45%, whereas 85% increase in flexural properties was observed. However the addition of wood–fibers resulted in a decrease in elongation at break and impact strength of the composites.
394 citations
TL;DR: In this paper, the tensile mechanical properties of flax fibres from the Hermes variety are estimated according to their diameter and their location in the stems, and the large scattering of these properties is ascribed to the variation of the fibre size along its longitudinal axis, as revealed by SEM observations.
Abstract: The tensile mechanical properties of flax fibres from the Hermes variety are estimated according to their diameter and their location in the stems. The large scattering of these properties is ascribed to the variation of the fibre size along its longitudinal axis, as revealed by SEM observations. The higher values of the mechanical properties for the fibres issued from the middle of the stems are associated with the chemical composition of their cell walls. The mechanical properties of unidirectional flax fibre/epoxy matrix composites are studied as a function of their fibre content. The properties of the composites are lower than those expected from single fibre characteristics.
349 citations
TL;DR: In this article, the performance of injection-molded short hemp fiber and hemp/glass fiber hybrid polypropylene composites was investigated. And the results showed that hybridization with glass fiber enhanced the performance properties.
Abstract: Natural fiber-based thermoplastic composites are generally lower in strength performance compared to thermoset composites. However, they have the advantage of design flexibility and recycling possibilities. Hybridization with small amounts of synthetic fibers makes these natural fiber composites more suitable for technical applications such as automotive interior parts. Hemp fiber is one of the important lignocellulosic bast fiber and has been used as reinforcement for industrial applications. This study focused on the performance of injection-molded short hemp fiber and hemp/glass fiber hybrid polypropylene composites. Results showed that hybridization with glass fiber enhanced the performance properties. A value of 101 MPa for flexural strength and 5.5 GPa for the flexural modulus is achieved from a hybrid composite containing 25 wt % of hemp and 15 wt % of glass. Notched Izod impact strength of the hybrid composites exhibited great enhancement (34%). Analysis of fiber length distribution in the composite and fracture surface was performed to study the fiber breakage and fracture mechanism. Thermal properties and resistance to water absorption properties of the hemp fiber composites were improved by hybridization with glass fibers. Overall studies indicated that the short hemp/glass fiber hybrid polypropylene composites are promising candidates for structural applications where high stiffness and thermal resistance is required. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2432–2441, 2007
325 citations
TL;DR: In this paper, the effects of the fibers (wood and bagasse) and coupling agent type/concentration on the composite properties were studied, and the composites had lower crystallization peak temperatures and wider crystalline temperature range than neat high density polyethylene (RHDPE), and their thermal stability was lower than RHDPE.
Abstract: Composites based on recycled high density polyethylene (RHDPE) and natural fibers were made through melt blending and compression molding. The effects of the fibers (wood and bagasse) and coupling agent type/concentration on the composite properties were studied. The use of maleated polyethylene (MAPE), carboxylated polyethylene (CAPE), and titanium-derived mixture (TDM) improved the compatibility between the bagasse fiber and RHDPE, and mechanical properties of the resultant composites compared well with those of virgin HDPE composites. The modulus and impact strength of the composites had maxima with MAPE content increase. The composites had lower crystallization peak temperatures and wider crystalline temperature range than neat RHDPE, and their thermal stability was lower than RHDPE.
297 citations
TL;DR: In this article, the chemical, physical, thermal and mechanical properties of curaua fibers, one of the unique fibers of the country, were determined for the first time, where the tensile strength and Young's modulus (YM) decrease while % strain at break remained constant as fiber diameter increases.
Abstract: Continuing the studies on the Brazilian lignocellulosic fibers, this paper presents chemical, physical, thermal and mechanical properties of curaua fibers, one of the unique fibers of the country. Stress–strain curves as a function of diameter of the fiber and static mechanical properties as functions of diameter, length of the fiber and as function of strain rate are determined for the first time. It was found that the tensile strength (TS) and Young’s modulus (YM) decrease while % strain at break remained constant as fiber diameter increases; decrease of TS and % strain at break and increase in YM as test length increased and an increase in TS and YM but without any change in % strain at break with increase of strain rate. Density, crystallinity, identification of chemical groups and degradation temperatures of these constituents of the fibers have been determined using pycnometer, X-ray diffraction, FTIR, UV and DTA/DSC instruments respectively. Dynamic mechanical analysis was also carried out, which revealed increase in modulus as the water present in the fiber is removed. All the results are discussed in terms of morphological observations including fractography.
TL;DR: In this paper, a green composite was fabricated by reinforcing a cornstarch-based biodegradable resin with high-strength natural fibers extracted from a plant named curaua.
Abstract: This paper describes development and improvement of mechanical properties of a so-called green composite that was fabricated by reinforcing a cornstarch-based biodegradable resin with high-strength natural fibers extracted from a plant named curaua. Two fabrication methods are proposed, in which stretched slivers of curaua fibers are prepared as reinforcement to increase the composite strength. Moreover, highly concentrated alkali treatment was applied to curaua fibers to improve mechanical properties of green composites. Tensile test results showed that alkali-treated fiber composites increased in fracture strain twice to three times more than untreated fiber composites, without a considerable decrease in strength. This result proves that appropriate alkali treatment is a key technology for improving mechanical properties of cellulose-based fiber composites.
TL;DR: In this paper, the effects of pre-treated flax fibers on the performance of fiber-reinforced composites were evaluated by using rotational molding to determine the tensile fracture surfa...
Abstract: The objective of this study was to determine the effects of pre-treated flax fibers on the performance of the fiber-reinforced composites. Lack of good interfacial adhesion and poor resistance to moisture absorption make the use of natural fiber-reinforced composites less attractive. In order to improve fiber/matrix interfacial properties, fibers were subjected to chemical treatments, namely, mercerization, silane treatment, benzoylation, and peroxide treatment. Selective removal of non-cellulosic compounds constitutes the main objective of the chemical treatments of flax fibers to improve the performance of fiber-reinforced composites. Flax fibers were derived from Saskatchewan-grown flax straws. Composites consisting of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) or HDPE/LLDPE mix, chemically treated fibers and additives were prepared by the extrusion process. The test samples were prepared by rotational molding. The fiber surface morphology and the tensile fracture surfa...
TL;DR: In this paper, a new structural composite material reinforced with unidirectional natural fibers is prepared and tested and used reinforcement is made of long Alfa fibers, extracted from the stem of the Alfa plant by the soda process.
TL;DR: In this paper, the effects of increasing wood fiber weight contents on mechanical, thermomechanical and morphological properties of the polyhydroxybutyrate-co-valerate (PHBV) based biocomposites were evaluated.
TL;DR: In this article, various chemical surface treatments have been performed on the Alfa (Stipa tenacissima) fiber, with the help of chemicals such as styrene (S), acrylic acid (AA), and maleic anhydride (MA).
TL;DR: An all-cellulose composite was prepared from conventional filter paper by converting a selective dissolved fiber surface into a matrix, which is composed of sustainable resources and is biodegradable after service, which gives it advantages with regard to disposal, composting, and incineration.
TL;DR: In this paper, the combination of oil palm fiber and glass fiber as reinforcing fibers in polyester composites was evaluated, and the hybrid effect of glass and EFB fibers on the tensile, flexural, impact, and hardness of the composites were investigated.
Abstract: In this research, the combination of oil palm fiber and glass fiber as reinforcing fibers in polyester composites was evaluated The mechanical and physical properties of oil palm empty fruit bunch/glass hybrid reinforced polyester composites were studied Hybrid laminate composites with different weight ratios (w/w) of chopped strand mat (CSM) glass fibers: oil palm empty fruit bunch fiber (EFB) 3: 7, 5: 5, 7: 3, 9: 1 were prepared The hybrid effect of glass and EFB fibers on the tensile, flexural, impact, and hardness of the composites were investigated Water absorption and thickness swelling were also conducted In general the hybrid composites exhibited good properties compared to the EFB/polyester composites
TL;DR: In this article, the properties of (randomly mixed) palmyra fiber, glass fiber hybrid composites are studied and the optimum fiber length and wt% are estimated and the results are presented as a function of square root of time.
Abstract: Use of eco friendly composites gains attraction due to its lightweight and moderate strength in the recent years. Palmyra fiber is a natural fiber obtained from Palmyra (Borassus flabellifer) tree. Mechanical properties of randomly mixed short fiber composites are studied and optimum fiber length and wt% are estimated. This paper deals with the properties of (randomly mixed) palmyra fiber, glass fiber hybrid composites. Two types of specimens are prepared, one by mixing the palmyra and glass fiber and the other by sandwiching palmyra fiber between the glass fiber mats. Composite plates are prepared for different palmyra/glass fiber weight ratio. Rooflite resin is used as matrix. Tensile, impact, shear and bending properties are studied. The mechanical properties of the composites are improved due to the addition of glass fiber along with palmyra fiber in the matrix. The glass fiber skin–palmyra fiber core construction exhibits better mechanical properties than dispersed construction. Moisture absorption studies are conducted and the results are presented as a function of square root of time. Addition of glass fiber with palmyra fiber in the matrix decreases the moisture absorption of the composites.
TL;DR: In this article, the effects of mercerization on shrinkage and fiber weight losses were monitored at different temperature and alkali concentration, and it was found that higher shrinkage of the polymer grafted fiber showed enhanced physico-mechanical properties.
TL;DR: In this article, the authors investigated the moisture absorption properties of short hemp fiber and hemp-glass hybrid reinforced thermoplastic composites to study their suitability in outdoor applications, and the 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 tempera.
Abstract: 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 tempera...
TL;DR: In this paper, the authors investigated the dynamic mechanical response and the short term creep-recovery behavior of composites made from bi-directional jute fabrics and polypropylene.
Abstract: The dynamic mechanical response and the short term creep-recovery behavior of composites made from bi-directional jute fabrics and polypropylene were studied. In order to improve the compatibility of the polar fibers and the non-polar matrix, two alternatives were compared: the addition of coupling agents and the chemical modification of the fibers. In the first case, two commercial maleated polypropylenes and lignin, a natural polymer, were used. In the second approach, the fibers were esterified using a commercial alkenyl succinic anhydride. The degree of interfacial adhesion was inferred from the measured properties and confirmed by the observation of the composite fractured surface. The maleated polypropylenes acted as compatibilizers since they were able to join the fibers to the neat PP, locating themselves in the interphase region. On the other hand, a clear separation between fibers and matrix could be observed when lignin was used as compatibilizing agent and when the chemically modified fibers were used to prepare the composite. The creep deformation could be directly related to the interfacial properties. Burgers model parameters were calculated from the creep part of the curves, and the recovery part was modeled using these values. A very good agreement between experimental data and theoretical curves were obtained in the creep region, although small discrepancies were found in the recovery part. The feasibility of the construction of a master curve (using the time–temperature principle) to predict long term creep behavior of the composites was investigated.
TL;DR: The aim of the study is the chemical modification of jute fibers using a fatty acid derivate (oleoyl chloride) to confer hydrophobicity and resistance to biofibers.
TL;DR: In this article, the potential of agro-residues such as wheat straw, cornstalk and corncob as reinforcements for thermoplastics as an alternative to wood fibers was investigated.
Abstract: The main objective of this research was to study the potential of agro-residues such as wheat straw, cornstalk and corncob as reinforcements for thermoplastics as an alternative to wood fibers. High-density polyethylene (HDPE) composites were prepared with a high content of agro-residues (65 wt.%). Surface chemistry of agro-residues was studied in comparison with wood flour with a view to evaluate its importance in determining the end-use properties of the composites. Surface chemistry showed a more carbon rich surface for wheat straw compared to cornstalk, corncob and wood flour. Thermal degradation characteristics of the fibers were studied to investigate the feasibility of these fibers to the processing point of view. The results showed that the agro-residues starts decomposition as low as 200 °C indicating that they can be processed with thermoplastics having a melt temperature less than 200 °C. Mechanical properties and water absorption properties of the composites were studied to evaluate the viability of these fibers as reinforcements in HDPE. Wheat straw filled HDPE composites exhibited superior mechanical properties compared to cornstalk, corncob and even wood flour filled HDPE, where as cornstalk showed comparable mechanical properties to that of wood flour–HDPE composite. All the composites exhibited a high uptake of water due to the high amount of filler present and incorporation of compatibilizer decreased the water uptake of the composites. It was observed that irrespective of the presence of compatibilizers, flexural properties of the composites were decreased considerably after water absorption.
TL;DR: In this article, a study focused on manufacturing of highly filled cellulose fiber-polypropylene composites and evaluation of the mechanical properties of the composites was conducted. But the results of the study were limited to cellulose fibres.
Abstract: This study focused on manufacturing of highly filled cellulose fibre–polypropylene composites and evaluation of the mechanical properties of the composites. Cellulose fibre reinforced polypropylene composites with up to 60 wt% of fibres with and without coupling agent were manufactured by extrusion. In order to achieve consistent feeding of the fibres into the extruder a pelletization technique was used where the fibres were pressed into pellets. Two commercial grades of cellulose fibres were used in the study, bleached sulfite and bleached kraft fibres. Fibre dimension measurements showed that the pelletization process and extrusion at high fibre loading caused the most severe fibre breakage. Flexural testing showed that increased fibre loading made the composites stiffer but reduced the toughness. Addition of maleic anhydride grafted coupling agent (MAPP) increased the stiffness and strength of the composites significantly. In general, there was no significant difference in the mechanical properties between the composites with kraft and sulfite fibres. An interesting finding was that the flexural modulus and strength of the MAPP modified cellulose fibre–polypropylene composites were not higher than what has previously been reported for wood flour–polyolefin composites. Scanning electron microscopy showed that addition of coupling agent improved the interfacial adhesion between the fibres and polypropylene matrix.
TL;DR: In this paper, Keratin fibers from chicken feathers were used as short-fiber reinforcement for a poly(methyl methacrylate) matrix, and the composites were evaluated via thermal and dynamical-mechanical analysis.
Abstract: Keratin fibers from chicken feathers were used as short-fiber reinforcement for a poly(methyl methacrylate) matrix. The composites were evaluated via thermal and dynamical–mechanical analysis. The thermal stability and transition temperature were found to be higher than standard PMMA. The storage modulus at room temperature increased with 1% and 2% weight of keratin biofibers and, at high temperature, the reinforcement provides higher stability, as reflected in the modulus behavior. Keratin fibers within the rigid polymer reduces tan δ peak, indication of a strong interface, as optical images confirm.
01 Jan 2007
TL;DR: In this paper, fully environment-friendly, sustainable and biodegradable green composites were fabricated using modified soy protein concentrate (SPC) resins and flax yarns and fabrics.
TL;DR: In this paper, a sulfur nano-silver colloidal solution (SNSE) having Ag/S complex, which was a particle size of average 4.2 nm in ethanol base was used to treat wool textiles with the silver colloid.
Abstract: We treated wool textiles with a sulfur nano-silver colloidal solution (SNSE) having Ag/S complex, which was a particle size of average 4.2 nm in ethanol base. The SNSE was a safe chemical agent having the perfect antibacterial efficacy with a very small amount of nano-sized silver and non-irritative solution to the skin. Antibacterial activity was evaluated by calculation of bacteria reduction against Gram-positive (Staphylococcus aureus) and Gram-negative (Klebsiella pneumoniae) bacteria. The treated wool textiles with the silver colloid were investigated the resistivity against insect pests through both calculation of the fiber loss weight and visible assessment attacked by larvae after 14 days in given conditions. Also, we confirmed the antistatic efficacy of the finished fabrics with silver particle on their surface. The static electricity of the treated wool fabric was increased more up to 50 ppm, then, it was decreased according to the silver content. Consequently, it was demonstrated that the finished wool fabrics with sulfur nano-silver colloid had various functionalities, such as mothproofing, antibiotic, and antistatic property.
TL;DR: In this paper, the effect of two surface treatments (acetylation and stearation) upon the tensile strength of flax fibres was discussed in terms of Gaussian statistics.
Abstract: Natural fibres are considered to be a potential alternative to glass fibres for use in composites applications. However, although natural fibres have many advantages their compatibility with most thermoplastics is rather poor. Surface treatments, although having a negative impact on economics, may be applied to overcome the problem of interfacial adhesion. Unfortunately, natural fibres being very different materials from man-made fibres, are very prone to degradation and/or structure alteration during the application of surface treatments. This study focuses on the effect of two surface treatments (acetylation and stearation) upon the tensile strength of flax fibres. The results are discussed in terms of Gaussian statistics and it was found that the treatments did not significantly change the flax fibre tensile strength. In addition SEM examination of the fractured surfaces revealed that acetylated fibres exhibit a different mode of failure from the other fibres, suggesting that the treatment altered the bulk properties along with the surface properties.