Effect of glass fiber on the electrical resistivities of polyoxymethylene/maleic anhydride‐grafted polyethylene/multiwalled carbon nanotube composites

The effect of glass fiber (GF) on the electrical resistivities of polyoxymethylene (POM)/maleic anhydride‐grafted polyethylene (MAPE)/multiwalled carbon nanotube (MWCNT) composites is investigated. The POM/MAPE/MWCNT composites at a MWCNT loading of 0.75% are nonconductive because most of MWCNTs are isolated in the MAPE islands, and their electrical resistivities decrease significantly after the addition of GF because of the formation of MAPE‐coated GF structure, which facilitates the formation of conductive paths and was confirmed by field emission scanning electron microscopy (FESEM). The formation of MAPE‐coated GF structure is attributed to the interaction between GF and MAPE during melt compounding, as contrasted by the uncoated GF using high‐density polyethylene (HDPE) instead of MAPE. Nonconductive POM/5–20% MAPE/0.75% MWCNT composites become conductive upon the addition of 20% GF. This preparation method for conductive materials can be generalized to POM/5–20% maleic anhydride‐grafted polypropylene (MAPP)/0.75% MWCNT composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41794.     

The mechanical and tribological properties of nitric acid‐treated carbon fiber‐reinforced polyoxymethylene composites

The carbon fibers have been exposed to nitric acid oxidation treatments and introduced into polyoxymethylene composites (POM/CF). The nitric acid treatment increases the number of the flaws, roughness of the surface, and disorder of carbon atoms on fiber, as well as introduces reactive functional groups, which could lead to a better mechanical bonding between fiber and the matrix. It is shown that the impact strength and fiber‐matrix adhesion in composites (POM/mCF) are superior to those for POM/CF composites. Simultaneously, the addition of mCF improves flexural strength and modulus relative to virgin POM significantly. Average friction coefficient values of POM/CF composites are lower than that of POM/mCF composites. As the percentage of fiber increases, the trend of wear ratio of the composites goes down initially and bumps up afterwards. The results indicate that the proper contents of CF and mCF in composites range from 5 wt % to 20 wt %. Scanning electron microscopy of worn surface morphology has revealed that the main wear mechanism of the composites were adhesive wear and ploughing wear. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41812.     

Thermal conductivity and tribological properties of POM‐Cu composites

The polyoxymethylene (POM) composites with different copper contents were prepared by extrusion. The thermal conductivity and tribological behavior of POM‐Cu composites with various contents of copper particles were investigated by a hot disk thermal analyzer and an M‐2000 friction and abrasion testing machine, respectively. The effect of copper particles on the thermal conductivity of POM composites was negligible when copper content was below 10 wt %. As the copper content increased, the thermal conductivity of composites increased and reached 0.477 W m^?1 K^?1 for POM‐25 wt % Cu composite, which increased by 35.9% compared with that of unfilled POM. The incorporation of copper particles into POM reduced the friction coefficient of POM composites. The wear mechanisms of POM‐Cu composites were adhesive and abrasive wear. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Mechanical,thermal, and morphological properties of maleic anhydride‐g‐polypropylene compatibilized and chemically modified banana‐fiber‐reinforced polypropylene composites

Composites were prepared with chemically modified banana fibers in polypropylene (PP). The effects of 40‐mm fiber loading and resin modification on the physical, mechanical, thermal, and morphological properties of the composites were evaluated with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Infrared (IR) spectroscopy, and so on. Maleic anhydride grafted polypropylene (MA‐g‐PP) compatibilizer was used to improve the fiber‐matrix adhesion. SEM studies carried out on fractured specimens indicated poor dispersion in the unmodified fiber composites and improved adhesion and uniform dispersion in the treated composites. A fiber loading of 15 vol % in the treated composites was optimum, with maximum mechanical properties and thermal stability evident. The composite with 5% MA‐g‐PP concentration at a 15% fiber volume showed an 80% increase in impact strength, a 48% increase in flexural strength, a 125% increase in flexural modulus, a 33% increase in tensile strength, and an 82% increase in tensile modulus, whereas the heat deflection temperature increased by 18°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of glass fiber on the properties of polyoxymethylene/thermoplastic polyurethane/multiwalled carbon nanotube composites

The effects of epoxy‐functionalized glass fiber (GF) on the electrical conductivity, crystallization behavior, thermal stability, and dynamic mechanical properties of polyoxymethylene (POM)/thermoplastic polyurethane (TPU)/multiwalled carbon nanotube (MWCNT) composites are investigated. The electrical resistivities of POM/5%−20% TPU/1% MWCNT composites are significantly reduced by nine orders of magnitude after the addition of 20% GF because of the formation of TPU‐coated GF structure facilitating the construction of conductive networks. GF has no obvious influence on the crystallization temperature, melting temperature, and degree of crystallinity of POM in POM/TPU/MWCNT composites because of their relatively bigger size compared with POM chains and MWCNTs. The storage moduli of POM/TPU/MWCNT composites are improved by the addition of GF, indicating that POM/TPU/MWCNT/GF composites are promising materials with good electrical and mechanical properties. POLYM. COMPOS., 38:1319–1326, 2017. © 2015 Society of Plastics Engineers     

Electrically conductive composites based on epoxy resin containing polyaniline–DBSA‐ and polyaniline–DBSA‐coated glass fibers

Four kinds of polyaniline (PANI)‐coated glass fibers (GF–PANI) combined with bulk PANI particles were synthesized. GF–PANI fillers containing different PANI contents were incorporated into an epoxy–anhydride system. The best conductivity behavior of the epoxy/GF–PANI composites was obtained with a GF–PANI filler containing 80% PANI. Such a composite shows the lowest percolation threshold at about 20% GF–PANI or 16% PANI (glass fiber‐free basis). The PANI‐coated glass fibers act as conductive bridges, interconnecting PANI particles in the epoxy matrix, thus contributing to the improvement of the conductivity of the composite and the lower percolation threshold, compared with that of a epoxy/PANI–powder composite. Particularly, the presence of glass fibers significantly improves the mechanical properties, for example, the modulus and strength of the conductive epoxy composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1329–1334, 2004     

Tensile behavior of glass‐fiber‐filled polyacetal: Influence of the functional groups of polymer matrices

We investigated the tensile behavior of glass‐fiber‐filled polyacetal [i.e., polyoxymethylene (POM)], focusing on the mutual influence of the functional groups in the POM matrices and the glass binder system. The different POM matrices were compounded with three kinds of glass fibers (20 wt %) treated with different glass binders, namely, epoxy resin, thermoplastic polyurethane (TPU), and a mixture of TPU and epoxy resin. A good correlation between the tensile strength and elongation at break was observed, regardless of the difference in the glass binders. The composites based on the modified POM matrix, which had both a carboxyl end group and a hydroxyl end group, improved the tensile properties noticeably in comparison with those based on the normal POM matrix. The composites were strengthened with an increase in the concentration of the functional groups. The results of scanning electron microscopy observations indicated that the fractured surfaces of a specimen having maximum tensile strength and elongation exhibited cohesion of the modified POM on the surfaces of the glass fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Mechanical properties of particulate‐filler/woven‐glass‐fabric‐filled vinyl ester composites

Studies of the effect of particulate fillers on specific mechanical properties of vinyl ester epoxy (VE) reinforced with woven glass fiber composites were carried out with different filler types and particulate filler contents (1%, 3%, and 5% by weight). Two types of particulate filler were used, i.e., calcium carbonate (CC) and phenolic hollow microspheres (PHMS). The composites were prepared by using a hand lay‐up and vacuum bagging method. Woven glass fabric composites filled with particulate PHMS were observed to have better specific flexural strength and specific impact strength, as well as lower density, than those filled with particulate CC. Morphological features determined by scanning electron microscope (SEM) proved that the PHMS filler experienced good bonding in the VE matrix, a feature which contributed to the improvement in the properties of the composites. The incorporation of particulate fillers into the composites also influenced the storage modulus with a minimal effect on T_g. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Kenaf‐bast‐fiber‐filled biodegradable poly(butylene succinate) composites: Effects of fiber loading,fiber length,and maleated poly(butylene succinate) on the flexural and impact properties

Poly(butylene succinate) (PBS) filled kenaf bast fiber (KBF) composites were fabricated via compression molding. The effects of KBF loading on the flexural and impact properties of the composites were investigated for fiber loadings of 10–40 wt %. The optimum flexural strength of the composites was achieved at 30 wt % fiber loading. However, the flexural modulus of the composites kept increasing with increasing fiber loading. Increasing the fiber loading led to a drop in the impact strength of about 57.5–73.6%; this was due to the stiff nature of the KBF. The effect of the fiber length (5, 10, 15, and 20 mm) on the flexural and impact properties was investigated for the 30 wt % KBF loaded composites. The composites with 10‐mm KBF showed the highest flexural and impact properties in comparison to the others. The inferior flexural and impact strength of the composites with 15‐ and 20‐mm KBF could be attributed to the relatively longer fibers that underwent fiber attrition during compounding, which consequently led to the deterioration of the fiber. This was proven by analyses of the fiber length, diameter, and aspect ratio. The addition of maleated PBS as a compatibilizer resulted in the enhancement of the composite's flexural and impact properties due to the formation of better fiber–matrix interfacial adhesion. This was proven by scanning electron microscopy observations of the composites' fracture surfaces. The removal of unreacted maleic anhydride and dicumyl peroxide residuals from the compatibilizers led to better fiber–matrix interfacial adhesion and a slightly enhanced composite strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Selective laser sintering of polyamide 12/potassium titanium whisker composites

The excellent performance of potassium titanium whiskers (PTWs) reinforced plastics has been recognized; however, because of their large length‐to‐diameter ratio, they have not been applied in selective laser sintering (SLS). This article reports a new method for preparing polyamide 12 (PA12)/PTWs composite (PPC) powders for applications in SLS that uses a dissolution–precipitation process. The characteristics of the powders were evaluated. The results indicated that when the PTWs content of the composites was low (<10 wt %), the shape of the powder became more regular, and the particle diameter distribution became narrower. The crystallinity of PPC was 13 wt % higher than that of PA12. The sintering characteristics and mechanical properties of PA12 powder, glass‐filled PA12 (GF–PA), and PPCs were compared. The results showed that the sintering characteristics of PPCs (10 or 20 wt % PTWs) were as good as those of PA12. The mechanical properties were greatly improved by PTWs. The maximum tensile strength, bending strength, and bending modulus of the composites containing 20 wt % PTW were 68.3 MPa, 110.9 MPa, and 2.83 GPa, respectively, and were much higher than those of PA12 and GF–PA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of glass fiber‐multiwall carbon nanotube hybrid structures for high‐performance conductive composites

The conductive polyamide 66 (PA66)/carbon nanotube (CNT) composites reinforced with glass fiber‐multiwall CNT (GF‐MWCNT) hybrids were prepared by melt mixing. Electrostactic adsorption was utilized for the deposition of MWCNTs on the surfaces of glass fibers (GFs) to construct hybrid reinforcement with high‐electrical conductivity. The fabricated PA66/CNT composites reinforced with GF‐MWCNT hybrids showed enhanced electrical conductivity and mechanical properties as compared to those of PA66/CNT or PA66/GF/CNT composites. A significant reduction in percolation threshold was found for PA66/GF‐MWCNT/CNT composite (only 0.70 vol%). The morphological investigation demonstrated that MWCNT coating on the surfaces of the GFs improved load transfer between the GFs and the matrix. The presence of MWCNTs in the matrix‐rich interfacial regions enhanced the tensile modulus of the composite by about 10% than that of PA66/GF/CNT composite at the same CNT loading, which shows a promising route to build up high‐performance conductive composites. POLYM. COMPOS. 34:1313–1320, 2013. © 2013 Society of Plastics Engineers     

Mechanical properties and dynamic mechanical analysis of thermoplastic‐natural‐rubber‐reinforced short carbon fiber and kenaf fiber hybrid composites

The hybridization of thermoplastic natural rubber based on carbon fiber (CF) and kenaf fiber (KF) was investigated for its mechanical and thermal properties. Hybrid composites were fabricated with a melt‐blending method in an internal mixer. Samples with overall fiber contents of 5, 10, 15, and 20 vol % were subjected to flexural testing, and samples with up to 30% fiber content were subjected to impact testing. For flexural testing, generally, the strength and modulus increased up to 15 vol % and then declined. However, for impact testing, higher fiber contents resulted in an increment in strength in both treated and untreated composites. Thermal analysis was carried out by means of dynamic mechanical analysis on composites with 15 vol % fiber content with fractions of CF to KF of 100/0, 70/30, 50/50, 30/70, and 0/100. Generally, the storage modulus, loss modulus, and tan δ for the untreated hybrid composite were more consistent and better than those of the treated hybrid composites. The glass‐transition temperature of the treated hybrid composite was slightly lower than that of the untreated composite, which indicated poor damping properties. A scanning electron micrograph of the fracture surface of the treated hybrid composite gave insight into the damping characteristics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Evaluation of dynamic elastic properties of wood‐filled polypropylene composites

Dynamic modulus of elasticity (MoE) and shear modulus of wood‐filled polypropylene composite at various filler contents ranging from 10% to 50% was determined from the vibration frequencies of disc‐shaped specimens. Wood filler was used in both fiber form (pulp) and powder form (wood flour). A novel compatibilizer, m‐isopropenyl‐α,α‐dimethylbenzyl‐isocyanate(m‐TMI) grafted polypropylene with isocyanate functional group was used to prepare the composites. A linear increase in dynamic MoE, shear modulus, and density of the composite was observed with the increasing filler content. Between the two fillers, wood fiber filled composites exhibited slightly better properties. At 50% filler loading, dynamic MoE of the wood fiber filled composite was 97% higher than that of unfilled polypropylene. Halpin‐Tsai model equation was used to describe the changes in the composite modulus with the increasing filler content. The continuous improvement in elastic properties of the composites with the increasing wood filler is attributed to the effective reinforcement of low‐modulus polypropylene matrix with the high‐modulus wood filler. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1706–1711, 2006     

Effect of ortho‐diallyl bisphenol A on the processability of phthalonitrile‐based resin and their fiber‐reinforced laminates

Sluggish and narrow process window of phthalonitrile resin has tremendously limited their wide applications. In this work, a novel phthalonitrile containing benzoxazine (4,4′‐(((propane‐2,2‐diylbis (2H‐benzo [e] [1,3]oxazine‐6,3 (4H)‐diyl) bis(3,1‐phenylene))bis(oxy)) diphthalonitrile, BA‐ph) with ortho‐diallyl bisphenol A (DABPA) was investigated. The processing window of the BA‐ph/DABPA blends were found from 50°C to 185°C, which was significantly broader than that of the pure BA‐ph (120–200°C). The composites were prepared through a curing process involving sequential polymerization of allyl moieties, ring‐opening polymerization of oxazine rings and ring‐forming polymerization of nitrile groups. BA‐ph/DABPA/GF(glass fiber) composite laminates were prepared in this study, and the composite laminate with BA‐ph/DABPA molar ratio of 2/2 showed an outstanding flexural strength and modulus of 560 MPa and 37 GPa, respectively, as well as a superior thermal and thermo‐oxidative stability up to 408 and 410°C. These outstanding properties suggest that the BA‐ph/DABPA/GF composites are suitable candidates as matrices for high performance composites. POLYM. ENG. SCI., 56:150–157, 2016. © 2015 Society of Plastics Engineers     

Injection‐molded high‐density polyethylene–hydroxyapatite–aluminum oxide hybrid composites for hard‐tissue replacement: Mechanical,biological, and protein adsorption behavior

In this article, we report the mechanical and biocompatibility properties of injection‐molded high‐density polyethylene (HDPE) composites reinforced with 40 wt % ceramic filler [hydroxyapatite (HA) and/or Al₂O₃] and 2 wt % titanate as a coupling agent. The mechanical property measurements revealed that a combination of a maximum tensile strength of 18.7 MPa and a maximum tensile modulus of about 855 MPa could be achieved with the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites. For the same composite composition, the maximum compression strength was determined to be 71.6 MPa and the compression modulus was about 660 MPa. The fractrography study revealed the uniform distribution of ceramic fillers in the semicrystalline HDPE matrix. The cytocompatibility study with osteoblast‐like SaOS2 cells confirmed extensive cell adhesion and proliferation on the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites. The cell viability analysis with the 3(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay revealed a statistically significant difference between the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites and sintered HA for various culture durations of upto 7 days. The difference in cytocompatibility properties among the biocomposites is explained in terms of the difference in the protein absorption behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of a bio‐based composite material from soybean oil and keratin fibers

A novel bio‐based composite material, suitable for electronic as well as automotive and aeronautical applications, was developed from soybean oils and keratin feather fibers (KF). This environmentally friendly, low‐cost composite can be a substitute for petroleum‐based composite materials. Keratin fibers are a hollow, light, and tough material and are compatible with several soybean (S) resins, such as acrylated epoxidized soybean oil (AESO). The new KFS lightweight composites have a density ρ ≈ 1 g/cm³, when the KF volume fraction is 30%. The hollow keratin fibers were not filled by resin infusion and the composite retained a significant volume of air in the hollow structure of the fibers. Due to the retained air, the dielectric constant, k, of the composite material was in the range of 1.7–2.7, depending on the fiber volume fraction, and these values are significantly lower than the conventional silicon dioxide or epoxy, or polymer dielectric insulators. The coefficient of thermal expansion (CTE) of the 30 wt % composite was 67.4 ppm/°C; this value is low enough for electronic application and similar to the value of silicon materials or polyimides used in printed circuit boards. The water absorption of the AESO polymer was 0.5 wt % at equilibrium and the diffusion coefficient in the KFS composites was dependent on the keratin fiber content. The incorporation of keratin fibers in the soy oil polymer enhanced the mechanical properties such as storage modulus, fracture toughness, and flexural properties, ca. 100% increase at 30 vol %. The fracture energy of a single keratin fiber in the composite was determined to be about 3 kJ/m² with a fracture stress of about 100–200 MPa. Considerable improvements in the KFS composite properties should be possible by optimization of the resin structure and fiber selection. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1524–1538, 2005     

Flammability characteristics and performance of halogen‐free flame‐retarded polyoxymethylene based on phosphorus–nitrogen synergistic effects

The flammability characteristics and thermal stability of a novel halogen‐free flame‐retardant compounding system based on polyoxymethylene (POM) were studied, and a very effective flame retarding formulation for POM was developed from a combination of ammonium polyphosphate (APP), melamine cyanurate (MC), novolak, and dipentaerythritol. The decomposition behavior of POM compounds was evaluated by thermogravimetric analysis. The compound shows optimal flame retardancy with a limiting oxygen index of 52.8 and flammability rating of UL94 V‐0, when 27 wt % APP, 9 wt % MC, 4 wt % novolak, and 4 wt % dipentaerythritol are simultaneously incorporated into POM. The presence of novolak and dipentaerythritol as char‐forming agents results in a dense and compact multicellular char residue for the test bar after combustion, while Fourier transform infrared spectra confirm a characteristic phosphorous‐ and carbon‐rich char resulting from the APP/MC formulation. The pyrolysis–gas chromatography/mass spectrometry analysis indicates that highly flammable formaldehyde gas, the main pyrolysis product of POM, is annihilated by amide derivatives produced by the pyrolysis of MC, imparting better flame retardancy. The comprehensive flame‐retardant mechanisms based on phosphorus–nitrogen synergism promote the high flame retardancy of POM to reach the nonflammability of V‐0 rating. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.     

Mechanical properties of graphene nanoplatelet/epoxy composites

Because of their high‐specific stiffness, carbon‐filled epoxy composites can be used in structural components in fixed‐wing aircraft. Graphene nanoplatelets (GNPs) are short stacks of individual layers of graphite that are a newly developed, lower cost material that often increases the composite tensile modulus. In this work, researchers fabricated neat epoxy (EPON 862 with Curing Agent W) and 1–6 wt % GNP in epoxy composites. The cure cycle used for this aerospace epoxy resin was 2 h at 121°C followed by 2 h at 177°C. These materials were tested for tensile properties using typical macroscopic measurements. Nanoindentation was also used to determine modulus and creep compliance. These macroscopic results showed that the tensile modulus increased from 2.72 GPa for the neat epoxy to 3.36 GPa for 6 wt % (3.7 vol %) GNP in epoxy composite. The modulus results from nanoindentation followed this same trend. For loadings from 10 to 45 mN, the creep compliance for the neat epoxy and GNP/epoxy composites was similar. The GNP aspect ratio in the composite samples was confirmed to be similar to that of the as‐received material by using the percolation threshold measured from electrical resistivity measurements. Using this GNP aspect ratio, the two‐dimensional randomly oriented filler Halpin–Tsai model adjusted for platelet filler shape predicts the tensile modulus well for the GNP/epoxy composites. Per the authors' knowledge, mechanical properties and modeling for this GNP/epoxy system have never been reported in the open literature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Wood‐fiber‐reinforced poly(lactic acid) composites: Evaluation of the physicomechanical and morphological properties

This article presents the results of a study of the processing and physicomechanical properties of environmentally friendly wood‐fiber‐reinforced poly(lactic acid) composites that were produced with a microcompounding molding system. Wood‐fiber‐reinforced polypropylene composites were also processed under similar conditions and were compared to wood‐fiber‐reinforced poly(lactic acid) composites. The mechanical, thermomechanical, and morphological properties of these composites were studied. In terms of the mechanical properties, the wood‐fiber‐reinforced poly(lactic acid) composites were comparable to conventional polypropylene‐based thermoplastic composites. The mechanical properties of the wood‐fiber‐reinforced poly(lactic acid) composites were significantly higher than those of the virgin resin. The flexural modulus (8.9 GPa) of the wood‐fiber‐reinforced poly(lactic acid) composite (30 wt % fiber) was comparable to that of traditional (i.e., wood‐fiber‐reinforced polypropylene) composites (3.4 GPa). The incorporation of the wood fibers into poly(lactic acid) resulted in a considerable increase in the storage modulus (stiffness) of the resin. The addition of the maleated polypropylene coupling agent improved the mechanical properties of the composites. Microstructure studies using scanning electron microscopy indicated significant interfacial bonding between the matrix and the wood fibers. The specific performance evidenced by the wood‐fiber‐reinforced poly(lactic acid) composites may hint at potential applications in, for example, the automotive and packaging industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4856–4869, 2006