Moisture absorption properties of wood‐fiber‐reinforced recycled polypropylene matrix composites

To reduce the moisture absorption of wood‐fiber‐reinforced recycled plastic composites (WRPCs), a coupling agent (KH550), methyl methacrylate (MMA), and maleic anhydride (MA) were used to modify the wood fibers. The surface‐treated wood fibers were mixed with recycled polypropylene and processing agents to fabricate the WRPCs. The mechanical properties and moisture absorption behavior of the WRPCs were determined. The results showed that the three surface treatment methods could effectively reduce the moisture absorption and thickness swelling of WRPCs. In Comparison to the properties of untreated wood‐fiber‐reinforced WRPCs, the moisture absorption ratio of WRPCs with wood fibers treated by MMA, KH550, and MA was reduced by 31.4%, 49.8%, and 38.2%, respectively, and the tensile strength was increased by 22.1%, 26.3%, and 4.2%, respectively. The impact toughness of the WRPCs was increased by 36.2% KH550 treatment and 19.2% for MMA treatment but was decreased by 4.2% for MA treatment. Coupling treatment of the wood fibers was the best way to reduce the moisture absorption of WRPCs, and this kind of WRPC possessed the best comprehensive properties. J. VINYL ADDIT. TECHNOL., 2010. © 2009 Society of Plastics Engineers     

Unsaturated polyester‐toughened epoxy composites: Effect of sisal fiber on thermal and dynamic mechanical properties

In the present study, the mechanical and thermal properties of sisal fiber‐reinforced unsaturated polyester (UP)‐toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier‐transform infrared spectroscopy. The UP‐toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber‐reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP‐toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP‐toughened epoxy system. The results showed that the tensile and flexural strength of (alkali‐silane)‐treated fiber (30 wt%) ‐reinforced composites increased by 83% and 55%, respectively, as compared with that of UP‐toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali‐silane)‐treated fiber and its composite exhibited higher thermal stability than the untreated and alkali‐treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP‐toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali‐silane‐treated fiber‐reinforced composites is found to be less as compared with the untreated fiber‐reinforced composite. J. VINYL ADDIT. TECHNOL., 23:188–199, 2017. © 2015 Society of Plastics Engineers     

Effects of the accelerated freeze‐thaw cycling on physical and mechanical properties of wood flour‐recycled thermoplastic composites

This study investigated durability performance of wood‐plastic composites (WPCs) that were exposed to accelerated cycling of water immersion followed by freeze thaw (FT). The WPCs used in this study were made of high‐density polyethylene (HDPE) or polypropylene (PP) with radiata pine (Pinus radiata) wood flour using hot‐press molding. These two types of plastics included both recycled and virgin forms in the formulation. In the experiments, surface color, flexural properties, and dimensional stability properties (water absorption and thickness swelling) were measured for the FT cycled composites and the control samples. Interface microstructures and thermal properties of the composites were also investigated. The results show that the water absorption and the thickness swelling of the composites increased with the FT weathering. In the meantime, the flexural strength and stiffness decreased. Scanning electron microscopy (SEM) images of the fractured surfaces confirmed a loss of interface bonding between the wood flour and the polymer matrix. Differential scanning calorimetry (DSC) showed a decrease in crystallization enthalpy and crystallinity of the wood flour‐plastic composites as compared with the neat PP and HDPE samples. The crystallinity of the FT cycled composites using the virgin plastics (vPP and vHDPE) increased; however, the composites with the recycled plastics decreased in comparison with corresponding control samples. In general, the properties of the composites were degraded significantly after the accelerated FT cycling. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Long‐term water uptake behavior of lignocellulosic‐high density polyethylene composites

Composites of different lignocellulosic materials and high‐density polyethylene were prepared and their long‐term water absorption behaviors were studied. Wood flour, rice hulls, newsprint fibers, and kenaf fibers were mixed with the polymer at 25 and 50 wt % fiber contents and 1 and 2% compatibilizer, respectively. Water absorption tests were carried out on injection‐molded specimens at room temperature for five weeks. Results indicated a significant difference among different natural fibers with kenaf fibers and newsprint fibers exhibiting the highest and wood flour and rice hulls the lowest water absorption values, respectively. Very little difference was observed between kenaf fiber and newsprint composites and between rice hulls and wood flour composites regarding their water uptake behavior. The difference between 25 and 50% fiber contents for all composite formulations increased at longer immersion times, especially for the composites with higher water absorption. Kenaf fiber composites containing 50% kenaf fibers exhibited the highest water diffusion coefficient. A strong correlation was found between the water absorption and holocellulose content of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3907–3911, 2006     

Coextruded polyethylene and wood‐flour composite: Effect of shell thickness,wood loading,and core quality

Coextruded recycled polyethylene and wood‐flour composites with core–shell structure were manufactured using a pilot‐scale coextrusion line. The influence of wood loadings and thickness of the shell layer and core quality on mechanical and water absorption properties of the composites were investigated. Core–shell structured profile can significantly improve flexural and impact strengths of composites especially when a relatively weak core was used. However, the coextruded profile with unreinforced shell may have a reduced modulus when a strong core was used. The shell layer also protected coextruded composites from long‐term moisture uptaking, leading to improved dimensional stability compared with the corresponding un‐coextruded controls. When the shell thickness was fixed, less wood loading in the shell layer did not cause obvious flexural modulus and dimension change but improved impact strength and water resistance of the coextruded composites. When wood loading in the shell layer was fixed, increased shell thickness improved impact strength but affected modulus negatively. Thickened shell layer helped reduce water uptaking but did not change dimensional stability of coextruded composites remarkably. Overall enhancement of composite strength was more pronounced for the weaker core system. Thus, the coextrusion technology can be used to achieve acceptable composite properties even with a relatively weak core system—offering an approach to use recycled, low quality plastic‐fiber blends in the core layer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Water absorption pattern and dimensional stability of oil palm fiber–linear low density polyethylene composites

The water absorption pattern and associated dimensional changes and solid loss of oil palm fiber–linear low density polyethylene composites was studied. The effects of fiber size (425–840, 177–425, and 75–177 μ), fiber loading (0, 10, 20, 30, 40, and 50%), and time of immersion (192 h at an interval of 24 h) on these parameters were also studied. Alkali treatment of fibers was done to reduce the hydrophilic nature of the composites and its effect was studied. It was found that the water absorption in most of the combinations followed typical Fickian behavior. The rate of water absorption and swelling increased with fiber loading. However, alkali treatment of the fibers resulted in a reduction of water absorption at higher fiber loadings only, and composites with higher fiber sizes exhibited higher water absorption. A sharp increase in the thickness swelling was observed in the initial days of immersion, which remained constant thereafter. The thickness swelling also increased with fiber size; however, a constant trend was not observed for the 75–177 μ fiber size. In addition to thickness swelling, composites also expanded linearly during water absorption; however, linear expansion was considerably less than thickness swelling. Higher fiber loading and alkali treatment caused more linear expansion. We observed that maximum solid loss on water immersion occurred with small‐sized and also alkali‐treated fiber composites. An increase in thickness and a decrease in linear dimension were observed after one sorption–desorption cycle. This irreversible change was also found to be proportional to fiber loading and alkali treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Concentration effect of γ‐glycidoxypropyltrimethoxysilane on the mechanical properties of glass fiber–epoxy composites

In this study, glass fibers were modified using γ‐glycidoxypropyltrimethoxysilane of different concentrations to improve the interfacial adhesion at interfaces between fibers and matrix. Effects of γ‐glycidoxypropyltrimethoxysilane on mechanical properties and fracture behavior of glass fiber/epoxy composites were investigated experimentally. Mechanical properties of the composites have been investigated by tensile tests, short beam tests, and flexural tests. The short‐beam method was used to measure the interlaminar shear strength (ILSS) of laminates. The tensile and flexural properties of composites were characterized by tensile and three‐point bending tests, respectively. The fracture surfaces of the composites were observed with a scanning electron microscope. On comparing the results obtained for the different concentrations of silane solution, it was found that the 0.5% GPS silane treatment provided the best mechanical properties. The ILSS value of heat‐cleaned glass fiber reinforced composite is enhanced by ∼59% as a result of the glass fiber treatment with 0.5% γ‐GPS. Also, an improvement of about 37% in tensile strength, about 78% in flexural strength of the composite with the 0.5% γ‐GPS treatment of glass fibers was observed. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Coextruded PVC/wood‐flour composites with WPC cap layers

Wood‐plastic composites (WPCs) can absorb moisture in a humid environment owing to the hydrophilic nature of the wood, thereby making the products susceptible to microbial growth and loss of mechanical properties. In this study, rigid poly(vinyl chloride) (PVC)/wood‐flour composites (core layer) were coextruded with either unfilled rigid PVC (cap layer) or rigid PVC filled with a small amount (5–27.5%) of wood flour (composite cap layers) in order to decrease or delay the moisture uptake. The thickness of the cap layer and its composition in terms of wood flour content were the variables examined during coextrusion. Surface color, moisture absorption, and flexural properties of both coextruded and noncoextruded (control) composite samples were characterized. The experimental results indicated that both unfilled PVC and composite cap layers can be encapsulated over rigid PVC/wood‐flour composites in a coextrusion process. The moisture uptake rate was lower when a cap layer was applied in the composites, and the extent of the decrease was a strong function of the amount of wood flour in the cap layer but insensitive to cap layer thickness. Overall, coextruding PVC surface‐rich cap layers on WPCs significantly increased the flexural strength but decreased the flexural modulus as compared with those of control samples. The changes in bending properties were sensitive to both cap layer thickness and wood flour content. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers     

Mechanical behavior of agro‐residue‐reinforced polypropylene composites

In this research, fully environment‐friendly, sustainable and biodegradable composites were fabricated, using wheat straw and rice husk as reinforcements for thermoplastics, as an alternative to wood fibers. Mechanical properties including tensile, flexural, and impact strength properties were examined as a function of the amount of fiber and coupling agent used. In the sample preparation, three levels of fiber loading (30, 40, and 50 wt %) and two levels of coupling agent content (0 and 2 wt %) were used. As the percentage of fiber loading increased, flexural and tensile properties increased significantly. Notched Izod results showed a decrease in strength as the percentage of fiber increases. With addition of 50% fiber, the impact strengths decreased to 16.3, 14.4, and 16.4 J/m respectively, for wheat straw‐, rice husk‐, and poplar‐filled composites. In general, presence of coupling agent had a great effect on the mechanical strength properties. Wheat straw‐ and rice husk‐filled composites showed an increase in the tensile and flexural properties with the incorporation of the coupling agent. From these results, we can conclude that wheat straw and rice husk fibers can be potentially suitable raw materials for manufacturing biocomposite products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Wood/plastic composites co‐extruded with multi‐walled carbon nanotube‐filled rigid poly(vinyl chloride) cap layer

Wood/plastic composites (WPCs) can absorb moisture in a humid environment due to the hydrophilic nature of the wood in the composites, making products susceptible to microbial growth and loss of mechanical properties. Co‐extruding a poly(vinyl chloride) (PVC)‐rich cap layer on a WPC significantly reduces the moisture uptake rate, increases the flexural strength but, most importantly, decreases the flexural modulus compared to uncapped WPCs. A two‐level factorial design was used to develop regression models evaluating the statistical effects of material compositions and a processing condition on the flexural properties of co‐extruded rigid PVC/wood flour composites with the ultimate goal of producing co‐extruded composites with better flexural properties than uncapped WPCs. Material composition variables included wood flour content in the core layer and carbon nanotube (CNT) content in the cap layer of the co‐extruded composites, with the processing temperature profile for the core layer as the only processing condition variable. Fusion tests were carried out to understand the effects of the material compositions and processing condition on the flexural properties. Regression models indicated all main effects and two powerful interaction effects (processing temperature/wood flour content and wood flour content/CNT content interactions) as statistically significant. Factors leading to a fast fusion of the PVC/wood flour composites in the core layer, i.e. low wood flour content and high processing temperature, were effective material composition and processing condition parameters for improving the flexural properties of co‐extruded composites. Reinforcing the cap layer with CNTs also produced a significant improvement in the flexural properties of the co‐extruded composites, insensitive to the core layer composition and the processing temperature condition. Copyright © 2009 Society of Chemical Industry     

Resistance of paper mill sludge/wood fiber/high‐density polyethylene composites to water immersion and thermotreatment

The disposal of paper mill sludge (PMS) is a difficult environmental problem. Thus, PMS has been used as a substitute for wood fiber (WF) to reinforce high‐density polyethylene (HDPE). In this study, we compared PMS–WF–HDPE composites with composites without PMS after water immersion and thermal treatment. Water immersion and thermal treatment were conducted at 25 and 70°C, respectively. The results show that the composites with PMS absorbed less water but lost more of their original flexural properties after immersion; thereby, their strength was compromised. These reduced mechanical properties could be partially restored after redrying. After the thermotreatment, the composites with added PMS lost their weight and flexural properties, whereas the composites without PMS gained flexural strength. The results show that the thermotreatment improved the impact strength of the composites when no more than one‐third of WF was replaced with PMS. Fourier transform infrared spectroscopy and energy‐dispersive X‐ray energy‐dispersive spectroscopy showed that the wood index of the PMS composite decreased more than the index of the non‐PMS composite, whereas the carbonyl index increased more. However, the PMS composite showed a lower increase in the total oxygen/carbon weight ratio. This study suggested that limited amounts of WF could be substituted with PMS to reinforce HDPE. However, WF–PMS–HDPE composites should not be used in hot, humid environments for long periods. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41655.     

Use of wet‐laid techniques to form flax‐polypropylene nonwovens as base substrates for eco‐friendly composites by using hot‐press molding

The wet‐laid process with flax (base) and polypropylene (binder) fibers has been used to obtain nonwovens for further processing by hot‐press molding. Mechanical characterization of nonwovens has revealed that slight anisotropy is obtained with the wet‐laid process as better tensile strength is obtained in the preferential deposition direction. The thermo‐bonding process provides good cohesion to nonwovens, which is critical for further handling/shaping by hot‐press molding. Flax:PP composites have been processed by stacking eight individual flax:PP nonwoven sheets and applying moderate temperature and pressure. As the amount of binder fiber is relatively low (<30 wt%) if compared with similar systems processed by extrusion and injection molding, it is possible to obtain eco‐friendly composites as the total content on natural fiber (flax) is higher than 70 wt%. Mechanical characterization of hot‐pressed flax:PP composites has revealed high dependency of tensile and flexural strength on the total amount of binder fiber as this component is responsible for flax fiber embedment which is a critical parameter to ensure good fiber–matrix interaction. Combination of wet‐laid techniques with hot‐press molding processes is interesting from both technical and environmental points of view as high natural fiber content composites with balanced properties can be obtained. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Effect of electron beam irradiation on physico–mechanical properties of wood flour–polyethylene composites

Agricultural lignocellulosic fiber (wood flour)‐waste was used to prepare composite materials through partial replacement of wood flour with low density polyethylene powder (LDPE) ranged from 10 to 20% by weight; these composites were made with and without electron beam irradiation (EB). The results obtained showed that, flexural strength, modulus of elasticity, modulus of rupture, and impact strength increase with increasing content of LDPE up to 20%. While, the percentages of thickness swelling and water absorption are decreased directly with increasing content of LDPE. Furthermore, the EB irradiation improves the physico‐mechanical properties of composite materials from 10 to 50 kGy. The results obtained are also confirmed by scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effects of poly(dimethyl siloxane) on the water absorption and natural degradation of poly(lactic acid)/oil‐palm empty‐fruit‐bunch fiber biocomposites

Composites were fabricated with poly(lactic acid) and oil‐palm empty‐fruit‐bunch (EFB) fibers with extrusion; this was followed by an injection‐molding technique. Before compounding, the surface of the fiber was modified through ultrasound and poly(dimethyl siloxane) (PDMS). The influences of the ultrasound and PDMS on the water absorption and biodegradability of the composites were investigated. Additionally, the composites were buried under soil for 6 months, and their biodegradability was assessed through different characterization techniques, such as tensile testing and weight loss and diffussability measurement. The changes on the surface of the fibers due to treatment were examined by scanning electron microscopy analysis, and the influences on the biodegradability of the composites were observed. Functional group analysis and possible changes before and after degradation were also examined by a Fourier transform infrared spectrophotometric technique. The results analyses revealed that the treatment of fibers improved the density of the fibers and reduced the water uptake of the composites. The overall weight loss due to soil burial testing was found to be maximum for the untreated‐fiber‐based composites (6.8%), whereas the ultrasound‐ and silane‐treated composites showed the minimum value of weight loss (3.7%). The deterioration of the tensile strength due to degradation was found to be at a maximum for the untreated‐fiber‐based composite (27%), whereas the ultrasound‐ and silane‐treated‐fiber‐based composites showed a minimum value of 8%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42784.     

Synthesis and characterization of short Grewia optiva fiber‐based polymer composites

Natural fibers, such as Flax, Sisal, Hibiscus Sabdariffa, and Grewia optiva (GO) possess good reinforcing capability when properly compounded with polymers. These fibers are relatively inexpensive, easily available from renewable resources, and possess favorable values of specific strength and specific modulus. The mechanical performance of natural fiber‐reinforced polymers (FRPs) is often limited owing to a weak fiber‐ matrix interface. In contrast, urea–formaldehyde (UF) resins are well known to have a strong adhesion to most cellulose‐containing materials. This article deals with the synthesis of short G. optiva fiber‐reinforced UF polymer matrix‐based composites. G. optiva fiber‐reinforced UF composites processed by compression molding have been studied by evaluating their mechanical, physical, and chemical properties. This work reveals that mechanical properties such as: tensile strength, compressive strength, flexural strength, and wear resistance of the UF matrix increase up to 30% fiber loading and then decreases for higher loading when fibers are incorporated into the polymer matrix. Morphological and thermal studies of the matrix, fiber, and short FRP composites have also been carried out. The swelling, moisture absorbance, chemical resistance, and water uptake behavior of these composites have also been carried out at different intervals. The results obtained lay emphasis on the utilization of these fibers, as potential reinforcing materials in bio‐based polymer composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Effect of interface modification on the mechanical properties of polystyrene‐sisal fiber composites

The effect of interface modification on the mechanical (tensile, impact and flexural) properties of polystyrene–sisal fiber composites was investigated. The interface modification was performed by treatment of sisal fibers with benzoyl chloride, polystyrene maleic anhydride (PSMA), toluene diisocyanate (TDI), methyl triethoxy silane and triethoxy octyl silane. These interface modifications improve the compatibility of hydrophilic sisal fiber with a hydrophobic polystyrene matrix and change the tensile, impact and flexural properties of the composite, but to varying degrees depending on the fiber modification. The treated fibers were analyzed by spectroscopic techniques. Scanning electron microscopy was used to investigate the fiber surface, fiber pullout, and fiber‐matrix interface.     

Contribution of wood fiber hygroexpansion to moisture induced thickness swelling of composite plates

One of the main drawbacks of wood fiber‐based composite materials is their propensity to swell due to moisture uptake. Because the wood fibers are usually the main contributor to hygroexpansion, it is of interest to quantify the hygroexpansion coefficient of wood fibers, to compare and rank different types of fibers. This investigation outlines an inverse method to estimate the transverse hygroexpansion coefficient of wood fibers based on measurements of moisture induced thickness swelling of composite plates. The model is based on composite micromechanics and laminate theory. Thickness swelling has been measured on polylactide matrix composites with either bleached reference fibers or crosslinked fibers. The crosslinking modification reduced the transverse hygroexpansion of the composites and the transverse coefficient of hygroexpansion of the fibers was reduced from 0.28 strain per relative humidity for reference fibers to 0.12 for cross‐linked fibers. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Bleached extruder chemi‐mechanical pulp fiber‐PLA composites: Comparison of mechanical,thermal, and rheological properties with those of wood flour‐PLA bio‐composites

An environmentally friendly bleached extruder chemi‐mechanical pulp fiber or wood flour was melt compounded with poly(lactic acid) (PLA) into a biocomposite and hot compression molded. The mechanical, thermal, and rheological properties were determined. The chemical composition, scanning electron microscopy, and Fourier transform infrared spectroscopy results showed that the hemicellulose in the pulp fiber raw material was almost completely removed after the pulp treatment. The mechanical tests indicated that the pulp fiber increased the tensile and flexural moduli and decreased the tensile, flexural, and impact strengths of the biocomposites. However, pulp fiber strongly reinforced the PLA matrix because the mechanical properties of pulp fiber‐PLA composites (especially the tensile and flexural strengths) were better than those of wood flour‐PLA composites. Differential scanning calorimetry analysis confirmed that both pulp fiber and wood flour accelerated the cold crystallization rate and increased the degree of crystallinity of PLA, and that this effect was greater with 40% pulp fiber. The addition of pulp fiber and wood flour modified the rheological behavior because the composite viscosity increased in the presence of fibers and decreased as the test frequency increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44241.     

Bio‐composites for structural applications: Poly‐l‐lactide reinforced with long sisal fiber bundles

Fully bio‐based and biodegradable composites were compression molded from unidirectionally aligned sisal fiber bundles and a polylactide polymer matrix (PLLA). Caustic soda treatment was employed to modify the strength of sisal fibers and to improve fiber to matrix adhesion. Mechanical properties of PLLA/sisal fiber composites improved with caustic soda treatment: the mean flexural strength and modulus increased from 279 MPa and 19.4 GPa respectively to 286 MPa and 22 GPa at a fiber volume fraction of V_f = 0.6. The glass transition temperature decreased with increasing fiber content in composites reinforced with untreated sisal fibers due to interfacial friction. The damping at the caustic soda‐treated fibers‐PLLA interface was reduced due to the presence of transcrystalline morphology at the fiber to matrix interface. It was demonstrated that high strength, high modulus sisal‐PLLA composites can be produced with effective stress transfer at well‐bonded fiber to matrix interfaces. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40999.     

Novel eco‐friendly biodegradable coir‐polyester amide biocomposites: Fabrication and properties evaluation

Biocomposites are prepared from a cheap, renewable natural fiber, coir (coconut fiber) as reinforcement with a biodegradable polyester amide (BAK 1095) matrix. In order to have better fiber‐matrix interaction the fibers are surface modified through alkali treatment, cyanoethylation, bleaching and vinyl grafting. The effects of different fiber surface treatments and fiber amounts on the performance of resulting bio‐composites are investigated. Among all modifications, cyanoethylated coir‐BAK composites show better tensile strength (35.50 MPa) whereas 7% methyl methacrylate grafted coir‐BAK composites show significant improvement in flexural strength (87.36 MPa). The remarkable achievement of the present investigation is that a low strength coir fiber, through optimal surface modifications, on reinforcement with BAK show an encouraging level of mechanical properties. Moreover, the elongation at break of BAK polymer is considerably reduced by the incorporation of coir fibers from nearly 400% (percent elongation of pure BAK) to 16‐24% (coir‐BAK biocomposites). SEM investigations show that surface modifications improve the fiber‐matrix adhesion. From biodegradation studies we find that after 52 days of soil burial, alkali treated and bleached coir‐BAK composites show significant weight loss. More than 70% decrease in flexural strength is observed for alkali treated coir‐BAK composites after 35 days of soil burial. The loss of weight and the decrease of flexural strength of degraded composites are more or less directly related.