Thermal and mechanical properties of sorbitol‐based epoxy resin cured with quercetin and the biocomposites with wood flour

After a bio‐based epoxy resin, sorbitol polyglycidyl ether (SPE) was mixed with a flavonoid, quercetin (QC) in tetrahydrofuran at an optimized epoxy/hydroxy ratio 1/1.2, the obtained SPE/QC solution was mixed with wood flour (WF), prepolymerized at 150°C, and subsequently compressed at 170°C for 3 h to give SPE‐QC/WF biocomposites (WF content:0, 20, 30, 40 wt %). The tan δ peak temperature of SPE‐QC without WF (85.5°C) was higher than that of SPE cured with conventional phenol novolac (81.0°C). In addition, diglycidyl ether of bisphenol A cured with QC had a higher tan δ peak temperature (145.1°C) than that cured with PN (90.8°C). The tan δ peak temperatures (106–113°C) of SPE‐QC/WF biocomposites were significantly higher than that of SPE‐QC. The tensile modulus of SPE‐QC/WF biocomposites increased with increasing WF content. A lower wavenumber shift of carbonyl stretching absorption peak in the FTIR spectrum of SPE‐QC/WF as compared with that of SPE‐QC suggested that hydroxy group of woody component forms hydrogen bonding with carbonyl group of quercetin moiety. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of biocomposites composed of glycerol‐based epoxy resins,tannic acid,and wood flour

After polyglycerol polyglycidyl ether (PGPE) and glycerol polyglycidyl ether (GPE) were mixed with tannic acid (TA) in ethanol and without solvent at epoxy/hydroxyl ratio 1/1, the obtained GPE‐TA and PGPE‐TA solutions were mixed with wood flour (WF), prepolymerized at 50°C, and subsequently compressed at 160°C for 3 h to give GPE‐TA/WF and PGPE‐TA/WF biocomposites with WF content 50–70 wt %, respectively. The storage moduli of the biocomposites in the rubbery state at more than 80°C were much higher than that of the control cured resins. The PGPE‐TA/WF composites had higher tensile modulus and rather lower tensile strength than PGPE‐TA. On the other hand, both the tensile modulus and strength of GPE‐TA/WF were much higher than those of GPE‐TA (2.4 GPa and 37 MPa). Those values of GPE‐TA/WF increased with WF content, became maximal values (5.1 GPa and 51 MPa) at WF content 60 wt %, and were lowered at 70 wt %. FE‐SEM analysis of the fractured surface of the biocomposites revealed that WF is tightly incorporated into the crosslinked epoxy resins. As a result of optimization of the epoxy/hydroxyl molar ratio for GPE‐TA/WF composite with WF content 60 wt %, the composite prepared at the ratio of 1.0/0.8 showed the highest tensile modulus and strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Wood‐derived phenol novolaks and their wood/epoxy biocomposites

Guaiacol novolak (GCN) and wood‐tar creosote novolak (WCN) were synthesized by the reactions of wood‐derived guaiacol and creosote with formalin, respectively, and used as hardeners of sorbitol polyglycidyl ether (SPE). Thermal and mechanical properties of the cured resins (SPE‐GCN and SPE‐WCN) and their biocomposites with wood flour (WF) were compared with those of the materials prepared by using a petroleum‐based phenol novolak (PN). Although tan δ peak temperatures of SPE‐GCN and SPE‐WCN were lower than that of SPE‐PN, that (58.5–70.8°C) of SPE‐GCN/WF(40–50 wt %) was higher than that (56.6–57.0°C) of SPE‐PN/WF(40–50 wt %). Tensile moduli of all the biocomposites increased by the addition of WF, while tensile strengths were rather reduced. When the biocomposites with the same WF content were compared, tensile modulus of SPE‐GCN/WF was higher than that of SPE‐PN/WF. The 5% weight loss temperatures (346–291°C) of SPE‐GCN and SPE‐GCN/WF were comparable to those (338–284°C) of SPE‐PN and SPE‐PN/WF. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41347.     

Preparation and properties of biocomposites composed of sorbitol‐based epoxy resin,pyrogallol–vanillin calixarene,and wood flour

The reaction of pyrogallol (PG) and vanillin (VN), both of which are derived from plant resources, in the presence of p‐toluenesulfonic acid gave PG–VN calixarene (PGVNC) mainly composed of guaiacyl pyrogallol[4]arene. After sorbitol polyglycidyl ether (SPE) was mixed with PGVNC in tetrahydrofuran at an optimized epoxy/hydroxy ratio 1/2.65, the obtained SPE/PGVNC solution was mixed with wood flour (WF), prepolymerized at 150°C, and subsequently compressed at 190°C for 3 h to give SPE–PGVNC/WF biocomposites with WF content 0–20 wt%. The tan δ peak temperature of SPE–PGVNC was 148.1°C, which was much higher than that of the SPE cured with petroleum‐based phenol novolac (SPE–PN) at an optimized epoxy/hydroxy ratio 1/1. Although tan δ peak temperature slightly decreased with increasing WF content, the storage moduli of the SPE–PGVNC/WF biocomposites in the rubbery state at more than 150°C were much higher than those of SPE–PGVNC and SPE–PN. Also, the tensile modulus and strength for SPE–PGVNC/WF increased with increasing WF content. Field emission‐scanning electron microscopy analysis of the biocomposites revealed that WF is tightly incorporated into the crosslinked epoxy resins. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Wood‐thermoplastic composites from wood flour and high‐density polyethylene

High‐density polyethylene/wood flour (HDPE/WF) composites were prepared by a twin‐screw extruder. The effects of WF, silane coupling agents, polymer compatibilizers, and their content on the comprehensive properties of the WF/HDPE composites have been studied in detail, including the mechanical, thermal, and rheological properties and microstructure. The results showed that both silane coupling agents and polymer compatibilizers could improve the interfacial adhesion between WF and HDPE, and further improve the properties of WF/HDPE composites, especially with AX8900 as a compatibilizer giving higher impact strength, and with HDPE‐g‐MAH as a compatibilizer giving the best tensile and flexural properties. The resultant composite has higher strength (tensile strength = 51.03 MPa) and better heat deflection temperature (63.1°C). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of ammonium polyphosphate modified with 3‐(methylacryloxyl) propyltrimethoxy silane on mechanical and thermal properties of wood flour–polypropylene composites

In this article, the influence of ammonium polyphosphate (APP) and ammonium polyphosphate modified with 3‐(Methylacryloxyl) propyltrimethoxy silane (M‐APP) on mechanical properties, flame retardancy, and thermal degradation of wood flour–polypropylene composites (WF/PP composites) have been investigated. Polypropylene grafted with m‐isopropenyl‐α,α‐dimethylbenzyl‐isocyanate (m‐TMI‐g‐PP) was used to improve the adhesion of WF/PP composites. APP and M‐APP were used as flame retardants. The experimental results demonstrated that addition of M‐APP obviously enhanced mechanical properties of WF/PP composites. According to cone calorimetry results, M‐APP is also an effective flame retardant for WF/PP composites, compared to that of APP. It was also found that M‐APP decreased the 1% weight loss temperature and increased char residue. The thermal degradation of wood flour based upon the first peak temperature of wood decreased from 329.3 to 322.9°C and the thermal degradation of PP based upon the second peak temperature of PP improve from 518.0 to 519.6°C, when M‐APP was added to the WF/PP composites. From SEM results the char layer of the 25% M‐APP systems is much more intumescent than that of the 25% APP systems, indicating that 3‐(Methylacryloxyl) propyltrimethoxy silane can improve the char‐forming ability of WF/PP composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biodegradability and mechanical properties of agro‐flour–filled polybutylene succinate biocomposites

The objective of this study was the production of rice husk flour (RHF) and wood flour (WF) filled polybutylene succinate (PBS) biocomposites as alternatives to cellulosic material filled conventional plastic (polyolefins) composites. PBS is one of the biodegradable polymers, made from the condensation reaction of 1,4‐butanediol and succinic acid that can be naturally degraded in the natural environment. We compared the mechanical properties between conventional plastics and agro‐flour–filled PBS biocomposites. We evaluated the biodegradability and mechanical properties of agro‐flour–filled PBS biocomposites according to the content and filler particle size of agro‐flour. As the agro‐flour loading was increased, the tensile and impact strength of the biocomposites decreased. As the filler particle size decreased, the tensile strength of the biocomposites increased but the impact strength decreased. The addition of agro‐flour to PBS produced a more rapid decrease in the tensile strength, notched Izod impact strength, and percentage weight loss of the biocomposites during the natural soil burial test. These results support the application of biocomposites as environmentally friendly materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1513–1521, 2005     

Effect of maleated polypropylene as a compatibilizer and hyperbranched polyester as a processing aid on polypropylene‐wood flour biocomposites

This work focused on two difficulties associated with preparation of polypropylene/wood flour (PP/WF) composites, viz. the compatibility of PP with WF and processing of the composites with high melt viscosity. Maleic anhydride‐grafted polypropylene (MAPP) was used in the preparation of PP composites to provide the compatibility between polymer and filler. Hyperbranched polyester (HBPE) was incorporated to check feasibility of it as a processing aid in the same. The PP/WF composites were formulated by melt compounding on a Brabender Plastograph EC. Blending effect of compatibilizer and processing aid HBPE on PP/WF biocomposites have been carried out on the basis of torque analysis, mechanical properties, morphology, and thermal stability. The investigation showed that HBPE improves the processibility of PP/WF composites than MAPP with respective to torque value. The mechanical and thermal properties slightly vary with change in relative proportion of MAPP and HBPE. J. VINYL ADDIT. TECHNOL., 24:179–184, 2018. © 2016 Society of Plastics Engineers     

Biocomposites composed of epoxidized soybean oil cured with terpene‐based acid anhydride and cellulose fibers

Epoxidized soybean oil (ESO) was cured with a terpene‐based acid anhydride (TPAn) at 150°C, and the thermal and mechanical properties of the cured product were compared with ESO cured with hexahydrophthalic anhydride (HPAn), maleinated linseed oil (LOAn), or thermally latent cationic polymerization catalyst (CPI). The ESO‐TPAn showed a higher glass transition temperature (67.2°C) measured by dynamic mechanical analysis than ESO‐HPAn (59.0°C), ESO‐LOAn (?41.0°C), and ESO‐CPI (10.0°C). The storage modulus at 20°C of ESO‐TPAn was higher than those of ESO‐LOAn and ESO‐CPI. Also, ESO‐TPAn showed higher tensile strength and modulus than the other cured ESOs. Regarding the biodegradability measured by biochemical oxygen demand in an activated sludge, ESO‐TPAn possessed some biodegradability, which was lower than that of ESO‐LOAn. Next, biocomposites composed of ESO‐TPAn and regenerated cellulose (lyocell) fabric were prepared by compression molding method. The tensile strength of ESO‐TPAn/lyocell composites increased with increasing fiber content. The tensile strength and modulus of ESO‐TPAn/lyocell composite with fiber content 75 wt % were 65 MPa and 2.3 GPa, which were three times higher than those of ESO‐TPAn. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure and properties of phase change materials based on HDPE,soft Fischer‐Tropsch paraffin wax,and wood flour

Phase‐change materials based on high density polyethylene (HDPE), soft Fischer‐Tropsch paraffin wax (M3), and alkali‐treated wood flour (WF) were investigated. The blend and composite samples were prepared by melt mixing using a Brabender Plastograph, followed by melt pressing. They were characterized in terms of their morphology, as well as thermal, mechanical, thermo‐mechanical, and water absorption properties. Although SEM micrographs showed some evidence of intimate contact between the WF particles and the HDPE matrix as a result of alkali treatment, poor filler dispersion, and interfacial adhesion were also observed. Partial immiscibility of the HDPE and the M3 wax was noticed, with the WF particles covered by wax. There was plasticization of the HDPE matrix by the wax, as well as partial cocrystallization, inhomogeneity and uneven wax dispersion in the polymer matrix. The HDPE/WF/M3 wax composites were more homogeneous than the blends. The presence of wax reduced the thermal stability of the blends and composites. Both the presence of M3 wax and WF influenced the viscoelastic behavior of HDPE. The HDPE/M3 wax blends showed an increase in the interfacial amorphous content as the wax content increases, which resulted in the appearance of a β‐relaxation peak. The presence of M3 wax in HDPE reduced the mechanical properties of the blends. For the composites these properties varied with WF content. An increase in wax content resulted to a decrease in water uptake by the composites, probably because the wax covered the WF particles and penetrated the pores in these particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of biocide treatments on durability of wood and bamboo/high density polyethylene composites against algal and fungal decay

The main objective of this study was to investigate the algal and fungal resistance of biocide‐treated wood flour (WF)/high density polyethylene (HDPE) and bamboo flour (BF)/HDPE composites. The biocides included 4,5‐dichloro‐2‐octyl‐isothiazolone (DCOIT), zinc pyrithione (ZPT), and carbendazim (MBC). Resistance to algae and fungi was evaluated by artificially accelerated tests. Treated and untreated samples were exposed to algae (Chlorella vulgaris, Ulothrix sp., Scenedesmus quadricauda, and Oscillatoria sp.) and fungi (Coriolus versicolor and Poria placenta) for 21 days and 12 weeks, respectively. The volatile components of WF and BF extractives were analyzed by gas chromatography‐mass spectrometry (GC‐MS). The results indicated that incorporation of DCOIT, ZPT, and MBC effectively enhanced the durability of WF/HDPE and BF/HDPE composites against algal and fungal decay. Accordingly, DCOIT, ZPT, and MBC can be used as potential biocides for both WF/HDPE and BF/HDPE composites. GC‐MS analysis suggested that palmitic acid, oleic acid, stigmasta‐3,5‐dien‐7‐one, and vanillin in WF possibly provided some resistance to fungal attack, whereas di (2‐ethylhexyl) phthalate and linoleic acid in BF were responsible for algal resistance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45148.     

Soybean and linseed oil‐based composites reinforced with wood flour and wood fibers

Composites consisting of a conjugated linseed or soybean oil‐based thermoset reinforced with wood flour and wood fibers have been prepared by free radical polymerization. The thermoset resin consists of a copolymer of conjugated linseed oil (CLO) or conjugated soybean oil (CSO), n‐butyl methacrylate (BMA), divinylbenzene (DVB), and maleic anhydride (MA). The composites were cured at 180°C and 600 psi and postcured for 2 h at 200°C under atmospheric pressure. The effect of varying filler load, time of cure, filler particle size, origin of the fillers, and resin composition has been assessed by means of tensile tests, DMA, TGA, Soxhlet extraction followed by ¹H‐NMR spectroscopic analysis of the extracts, and DSC. The best processing conditions have been established for the pine wood flour composites. It has been observed that the addition of MA to the resin composition improves the filler‐resin interaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reinforcement on the mechanical‐, thermal‐, and water‐resistance properties of the wood flour/chitosan/poly(vinyl chloride) composites by physical and chemical modification

In this study, we aimed to physically and chemically modify wood flour (WF)/chitosan (CS) mixtures to reinforce the mechanical‐, thermal‐, and water‐resistance properties of WF/CS/poly(vinyl chloride) (PVC) composites with a three‐step modification process. This was a vacuum‐pressure treatment of sodium montmorillonite, inner intercalation replacement of organically modified montmorillonite, and surface grafting of glycidyl methacrylate (GMA). The untreated and modified mixtures were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy–energy‐dispersive spectroscopy, thermogravimetric analysis, and contact angle measurement. Meanwhile, the mechanical strengths and water absorption of WF/CS/PVC were estimated. The results indicate that the samples had a better performance after they were modified by montmorillonite (MMT) + GMA than when they were modified by only MMT. MMT and GMA showed a very synergistic enhancement to the mechanical‐, thermal‐, and water‐resistance properties of the WF/CS/PVC composites. Specifically, the maximum flexural and tensile strengths were increased by 10.59 and 12.28%, respectively. The maximum water absorption rate was decreased by 61.99%, and the maximum degradation temperature was delayed to the higher value from 314.3 and 374.9°C in the untreated sample to 388.8 and 412.8°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40757.     

Crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites

The isothermal crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites (PLA/α‐cellulose) was examined using a differential scanning calorimeter and a petrographic microscope. Incorporating a natural micro‐sized cellulose filler increased the spherulite growth rate of the PLA from 3.35 μm/min for neat PLA at 105°C to a maximum of 5.52 μm/min for the 4 wt % PLA/α‐cellulose composite at 105°C. In addition, the inclusion of α‐cellulose significantly increased the crystallinities of the PLA/α‐cellulose composites. The crystallinities for the PLA/α‐cellulose composites that crystallized at 125°C were 48–58%, higher than that of the neat PLA for ～13.5–37.2%. The Avrami exponent n values for the neat and PLA/α‐cellulose composites ranged from 2.50 to 2.81 and from 2.45 to 3.44, respectively, and the crystallization rates K of the PLA/α‐cellulose composites were higher than those of the neat PLA. The activation energies of crystallization for the PLA/α‐cellulose composites were higher than that of the neat PLA. The inclusion of α‐cellulose imparted more nucleating sites to the PLA polymer. Therefore, it was necessary to release additional energy and initiate molecular deposition. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flammability and mechanical properties of wood flour‐filled polypropylene composites

Polypropylene (PP) composites filled with wood flour (WF) were prepared with a twin‐screw extruder and an injection‐molding machine. Three types of ecologically friendly flame retardants (FRs) based on ammonium polyphosphate were used to improve the FR properties of the composites. The flame retardancy of the PP/WF composites was characterized with thermogravimetric analysis (TGA), vertical burn testing (UL94‐V), and limiting oxygen index (LOI) measurements. The TGA data showed that all three types of FRs could enhance the thermal stability of the PP/WF/FR systems at high temperatures and effectively increase the char residue formation. The FRs could effectively reduce the flammability of the PP/WF/FR composites by achieving V‐0 UL94‐V classification. The increased LOI also showed that the flammability of the PP/WF/FR composites was reduced with the addition of FRs. The mechanical property study revealed that, with the incorporation of FRs, the tensile strength and flexural strength were decreased, but the tensile and flexural moduli were increased in all cases. The presence of maleic anhydride grafted polypropylene (MAPP) resulted in an improvement of the filler–matrix bonding between the WF/intumescent FR and PP, and this consequently enhanced the overall mechanical properties of the composites. Morphological studies carried out with scanning electron microscopy revealed clear evidence that the adhesion at the interfacial region was enhanced with the addition of MAPP to the PP/WF/FR composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of bamboo fiber‐graft‐lauryl methacrylate and its composites with polypropylene

In this study, lauryl methacrylate grafted onto bamboo fibers (BF‐g‐LM) was prepared to improve the interfacial compatibility between hydrophilic bamboo fibers (BFs) and hydrophobic plastic. The lauryl methacrylate (LM) was initiated by benzoxyl peroxide (BPO) and grafted onto BFs via a free‐radical chain‐transfer reaction. LM was grafted onto BFs with ether bonds, and differential scanning calorimetry indicated that the ether pyrolysis of BF‐g‐LM occurred at 280°C. The optimum preparation conditions were obtained as follows: 0.30 g of pretreated bamboo flour was immersed in 0.225 mol/L LM. The reaction was then initiated by 0.025 mol/L BPO, and this reaction was sustained for 4 h at 80°C. BF‐g‐LM served as coupling agent between the BFs and the polypropylene (PP) matrix, as shown by scanning electron microscopy analysis. The elongation at break of the BF/PP composites with BF‐g‐LM increased to two times compared to that of the BF/PP composites without BF‐g‐LM. The impact strength and maximum deflection also increased to 75 and 580%, respectively. In conclusion, BF‐g‐LM is a promising coupling agent that can be used in BF‐reinforced thermoplastic composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2377–2382, 2013     

Creep resistance of wood‐filled polystyrene/high‐density polyethylene blends

Creep, the deformation over time of a material under stress, is one characteristic of wood‐filled polymer composites that has resulted in poor performance in certain applications. This project was undertaken to investigate the advantages of blending a plastic of lower‐creep polystyrene (PS) with high‐density polyethylene (HDPE) at ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. These various PS–HDPE blends were then melt blended with a short fiber‐length wood flour (WF). Extruded bars of each blend were examined to measure modulus of elasticity and ultimate stress. Increasing the ratio of WF increased modulus of elasticity in all composites, except between 30 and 40% WF, whereas the effect of WF on ultimate stress was variable, depending on the composite. Scanning electron microscopic images and thermal analysis indicated that the wood particles interacted with the PS phase, although the interactions were weak. Finally, creep speed was calculated by using a three‐point bending geometry with a load of 50% of the ultimate stress. Creep decreased only slightly with increasing WF content but more significantly with increasing PS content, except at pure PS. The WF/75PS–25HDPE blend showed the least creep. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 418–425, 2001     

Mechanical and thermal flow properties of wood flour–biodegradable polymer composites

Wood flour (WF)–polycaprolactone (PCL) and polybutylenesuccinate–butylenecarbonate (PBSC) composites were prepared by knead processing. The effects of a compatibilizer on the tensile and thermal flow properties of the composites were investigated. PCL‐graft‐maleic anhydride (PCL‐g‐MA) was used as a compatibilizer. Tensile properties were improved by adding PCL‐g‐MA to both composites. The tensile strength and Young's modulus were increased from 13 to 27 MPa and 581 to 1011 MPa in WF–PCL (50/50, w/w) composites, respectively, and from 17 to 28 MPa and 814 to 1007 Mpa in WF–PBSC (50/50, w/w) composites, respectively, with the addition of 5% PCL‐g‐MA. Elongation at break increased from 4 to 7% and from 3 to 6% in the WF–PCL and the WF–PBSC composites, respectively. Tensile strength was further increased with increasing WF content in the presence of PCL‐g‐MA. Thermal flow temperature and melt viscosity of the composites were increased, and water absorption and thickness swelling were improved with the addition of PCL‐g‐MA. It was found from the burial test that all composites were more than 40% degraded within 6 weeks, and there was no considerable difference in degradation between composites with PCL‐g‐MA and those without. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1900–1905, 2003     

Morphological,mechanical, and physical properties of composites made with wood flour‐reinforced polypropylene/recycled poly(ethylene terephthalate) blends

Wood flour (WF)‐filled composites based on a polypropylene (PP)/recycled polyethylene terephthalate (r‐PET) matrix were prepared using two‐step extrusion. Maleic anhydride grafted polypropylene (MAPP) was added to improve the compatibility between polymer matrices and WF. The effects of filler and MAPP compatibilization on the water absorption, mechanical properties, and morphological features of PP/r‐PET/WF composites were investigated. The addition of MAPP significantly improved mechanical properties such as tensile strength, flexural strength, tensile modulus, and flexural modulus compared with uncompatibilized composites, but decreased elongation at break. Scanning electron microscopic images of fracture surface specimens revealed better interfacial interaction between WF and polymer matrix for MAPP‐compatibilized PP/r‐PET/WF composites. MAPP‐compatibilized PP/r‐PET/WF composites also showed reduced water absorption due to improved interfacial bonding, which limited the amount of absorbable water molecules. These results indicated that MAPP acts as an effective compatibilizer in PP/r‐PET/WF composites. POLYM. COMPOS., 38:1749–1755, 2017. © 2015 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.