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Nanocrystalline cellulose (NCC) was used as a modifier for waterborne polyurethane (WPU) to investigate the water and ethanol resistance of WPU-NCC composites. The NCC surface was modified with γ-glycidoxypropyltrimethoxysilane (GPTMS) and γ-ammnonimpropylmethyldimethoxysilane (APMDS) to improve its compatibility with waterborne polyurethane (WPU), as indicated by the contact angle (CA). The characteristic properties of WPU modified by NCC and a control group were compared by a Fourier-transform infrared spectroscope (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The CA between the modified NCC and WPU was decreased by 31.2% (with 8.0% APMDS (v/v)), and the NCC modified by GPTMS resulted in a 33.8% decrease of the CA. Compared to the original WPU, the crystal structure and crystallinity of the modified WPU showed a slight alteration. The SEM micrographs showed that the NCC particles modified by GPTMS were dispersed more uniformly. The FT-IR results showed that the addition of modified NCC led to the reduction of the characteristic absorption peak of the hydroxyl group. The water resistance of WPU with 1.5% NCC modified by GPTMS was increased by 47.2%, and the ethanol resistance decreased by 67.0%, while the modification from APMDS led to a 38.1% increase in water resistance and a 56.9% decrease in ethanol resistance. [ABSTRACT FROM AUTHOR]

The effect of unmodified talc particles on the mechanical and thermal expansion performance of talc-filled high density polyethylene (HDPE) and co-extruded wood plastic composite (WPC) with talc-filled shells was studied. The use of talc in HDPE helped enhance its tensile, bending, and dynamic modulus, but lowered its tensile and impact strength. The selected models for composite modulus and tensile strength fit the data well after adjusting the model parameters. Talc-filled HDPE had lower linear coefficient of thermal expansion (LCTE) values in comparison with the neat HDPE values, and the LCTE reduction rate increased after the talc loading levels increased above the 30 wt%. Extruding a relatively thick, less-stiff HDPE shell with a large LCTE value over a stiff and thermally stable WPC core decreased overall composite modulus and increased the LCTE values. The composite modulus and strength increased and LCTE values decreased with increase of the talc loading levels in the shell. The impact strength of co-extruded WPC was greatly enhanced with unfilled- and filled HDPE shells. [ABSTRACT FROM AUTHOR]

Stress relaxation has been proven to be a good measure for studying the interaction between the constituents in wood flour/polymer composites by evaluating the internal bonding quantitatively. In order to investigate the combination effect of polyethylene glycol (PEG) impregnation and heat treatment on the interfacial compatibility of wood flour/polypropylene composites, the stress relaxation of PEG and/or thermally modified wood flour/polypropylene composites was determined at three temperatures (26, 40, and 60 °C). The apparent activation energy (ΔE) was also calculated according to Eyring's absolute rate reaction theory. The results showed that PEG treatment accelerated the stress relaxation rate of the composites and decreased the ΔE. However, heat treatment resulted in an alleviation of the increasing rate of stress relaxation caused by PEG modification and an increase in the ΔE of the composites. These results suggested that PEG treatment had a negative effect on the interfacial compatibility between wood flour and polypropylene in the composites, and heat treatment could compensate for this effect to a certain extent. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the deformation behavior and damage model of bamboo bundle corrugated laminated composites under low velocity impact loading. The influence of different stacking sequences, i.e., bamboo bundle parallel to the corrugated waves (type I), cross-ply (type II), and perpendicular to the waves (type III), in laminates was studied in regard to impact loading. A shape parameter, K, was developed to quantify the effect of corrugation on impact response. The results of this study indicated that the type I composites displayed the optimum impact performance, followed by types II and III. The total energy absorbed by the type I laminates was 1.3 and 2.2 times as much as types II and III. The values of peak load were type I > type II > type III. The composites deformed and failed in different manners under low velocity impact loading: material failure, delamination and fiber tensile fracture, and structural collapse were the main modes of failure for type I, II, and III, respectively. The effect of the corrugated shape on impact properties of composites was positive for type I, but negative for type II composites. [ABSTRACT FROM AUTHOR]

Five kinds of commercially available wood-based composites (softwood plywood, hardwood plywood, medium density fiberboard, oriented strand board, and particle board, hereinafter abbreviated as SWP, HWP, MDF, OSB, and PB, respectively) post-treated with alkaline copper quat (ACQ) and copper azole (CA) were exposed to decay and subterranean termite activity under protected above-ground conditions in a southern Japan field test site for three years. Variables examined included comparisons of untreated and treated wood-based composites, preservative type, and retention levels. Both biological attacks developed with time. Termite damage started earlier, and the severity of attack was higher than decay fungi. Untreated MDF and PB were highly resistant to field conditions during the 36 months. Untreated OSB, HWP, and SWP were the least resistant composite types. ACQ and CA treatments significantly improved the durability of the wood-based composites resulting in 64.4%, 47.9%, and 22.5% higher termite ratings when compared to their untreated controls for OSB, HWP, and SWP, respectively. Preservative types and increased retentions did not significantly affect the decay and termite ratings. These results suggest that ACQ and CA post-treatments at exterior protected and unprotected (K3) and double K3 retention levels significantly improved durability of wood-based composites tested but failed to provide full protection. [ABSTRACT FROM AUTHOR]

The effects of kenaf (KNF) loading and 3-aminopropyltriethoxysilane (APTES) on the tensile properties, water uptake, and thermal properties of KNF-filled polypropylene (PP)/waste pulverized tire (WPT) composites were investigated. The composites were prepared using a Thermo Haake Polydrive internal mixer, where KNF loadings (0, 5, 10, 15, 20 phr) and constant PP/WPT (70/30) were used. The results showed that the tensile modulus and water uptake increased, but tensile strength and elongation at break decreased, with increased KNF loading. The composites with APTES exhibited a higher tensile strength and tensile modulus, but lower elongation at break and water uptake than composites without APTES. The presence of APTES enhanced the interfacial adhesion between PP/WPT matrices and KNF. Thermal stability of PP/WPT/KNF composites increased with KNF loading, and was found slightly higher, but insignificant for composites with APTES. Fourier transform infrared (FTIR) spectra analysis was performed to study the interactions among the PP, WPT, KNF, and the ethoxy functional groups in APTES. [ABSTRACT FROM AUTHOR]

The effect of zinc borate (ZB) treatment on the mechanical and morphological properties of wood flour/polypropylene composites was investigated. Wood flour was first treated with ZB solution (1% w/w in ethanol-distilled water), followed by 24 hours of soaking on an unheated magnetic stirrer hot plate until relatively complete saturation was reached. Then, composites based on ZB-pretreated, ZB-treated-during-manufacturing, and untreated wood flour, polypropylene and coupling agent were made by melt compounding and then injection molding. The ZB treatment had no significant influence on mechanical properties of the composite with the exception of tensile strength. The composite made with ZB-pretreated wood flour exhibited the same mechanical properties as the composites made with ZB-in-process-treated wood flour; however there were statistically significant differences between flexural modulus and tensile strength of ZB-pretreated composites and ZB-in-process treated ones. Specimens containing the ZB showed lower flexural, tensile, and impact strength compared with the untreated specimens. However, the zinc borate treatments produced modest improvements in hardness performance. The SEM micrographs revealed that the outer surface of the wood fibers was coated by some crystalline deposits of zinc borate. [ABSTRACT FROM AUTHOR]

Heat treatment under controlled temperatures can help enhance bamboo's durability and dimensional stability. The treatment may simultaneously affect thermal and mechanical performance of bamboo fibers (BFs). The aim of this work was to study the effect of heat treating temperature on thermal decomposition kinetic properties of heat-treated BFs and resulting polymer composites using dynamic thermo-gravimetric analysis under nitrogen. Degradation models including the Kissinger and the Flynn-Wall-Ozawa methods were used to determine the apparent activation energy (Ea) of various materials. The results indicated that the thermal decomposition of the heat-treated BFs mainly occurred within a temperature range between 245°C and 354°C. The values of Ea varied from 161 to 177 kJ/mol and increased with increased heat treating temperatures for the fibers. The thermal decomposition of the heat- treated BF and high density polyethylene blends mainly occurred within a temperature range of 307°C and 483°C. The values of Ea were between 225 and 236 kJ/mol and decreased with the increase of fiber heat-treating temperatures. The established thermal decomposition kinetic parameters can help aid the development of polymer composites from heat-treated bamboo materials. [ABSTRACT FROM AUTHOR]

Effects of different resination techniques relative to the mechanical properties of commercially produced thick medium density fiberboard (MDF) were investigated. The amount of urea-formaldehyde resin (11 wt%) applied to the wood fibers was gradually decreased in the blowline (11, 10.5, 10, and 9.5 wt%), while it was gradually increased in the short- retention blender (0, 0.5, 1, and 1.5. wt%). The internal bond strength of the MDF boards considerably improved as the amount of the resin applied to the fibers in the short-retention blender was increased to 1.5 wt%. In particular, the increase in the IB strength was most pronounced as the resin content increased from 1 to 1.5%. The edge and face screw withdrawal resistances increased by 7.7 and 7.9% as the amount of the resin applied to the fibers in the blender was increased. Similar values were also observed for the flexural properties. Overall, the total resin content in the production of thick MDF can be decreased as blender resination, a means of post-dryer resin addition, is incorporated into the blowline resination technique. [ABSTRACT FROM AUTHOR]

Melamine formaldehyde (MF) composites filled with rice husk powder were prepared by compression molding. The curing processes of the composites with different powder contents and powder particle sizes were studied by dynamic mechanical analysis. Gelation temperature and curing time were subjected to optimization of their mechanical and thermal properties. The rice husk powder loading in the MF matrix and the powder particle size were found to be critical factors governing the curing behavior and properties of the composite. Composites with larger content or smaller powder size had higher gelation temperatures and lower viscosities. The curing times of the composites were also influenced by the powder content. Flexural strength and flexural modulus increased with powder loading in the 20 to 90 mesh particle size range, while notched impact strength decreased. The mechanical properties of the composites decreased to a considerable extent when the fibers were too small to achieve strong interfacial adhesion. Morphological (scanning electron microscopy) and thermal studies (heat deflection temperature) were also conducted. [ABSTRACT FROM AUTHOR]

Hybrid composites of polyethylene/wood flour/nanoclay with different concentrations of nanoclay were fabricated using melt compounding followed by injection molding. Composites were weathered in a xenon- arc type accelerated weathering apparatus for 2000 h. Physical properties of the composites were evaluated by colorimetery and water absorption before and after weathering. Changes in surface chemistry were monitored using spectroscopic techniques. The results indicated that water absorption of the composites increased after weathering, but nanoclay can reduce the intensity of weathering to some extent by decreasing water absorption. Weathering increased the degree of color change and lightness of the samples; however, the lightness of the samples containing nanoclay was less than that of neat wood-plastic composites. Fourier transform infrared spectroscopy revealed a lower carbonyl index of composites containing nanoclay. X-ray diffraction patterns revealed that the nanocomposites formed were intercalated. The order of intercalation for samples containing 2 wt% nanoclay was higher than that of 4 wt% at the same maleic anhydride grafted polyethylene content, due to some agglomeration of the nanoclay. [ABSTRACT FROM AUTHOR]

In this work, nanofibrillated cellulose (NFC) has been evaluated as a potential reinforcement for cement mortar composites. Two types of vegetable fibres with different composition and properties (cellulose content and microfibrillar angle), sisal, and cotton linters pulps, were initially characterised in order to assess their reinforcing capability. Sisal pulp was found to be most suitable as reinforcement for the brittle cementitious matrix. Nanofibrillated cellulose was produced by the application of a high intensity refining process of the sisal pulp. It was found that 6 hours of refining time was required to obtain the desired nanofibrillation of the fibers. Cement mortar composites reinforced with both the sisal fibres and the nanofibrillated cellulose were prepared, and the mechanical properties were determined under flexural tests. The cement mortar composites reinforced with the nanofibrillated cellulose exhibited enhanced flexural properties, but lower values of fracture energy, than the ones reinforced with the conventional sisal fibres. [ABSTRACT FROM AUTHOR]

In this study, powdered activated carbon (PAC) was produced from agricultural waste biomass of kenaf (Hibiscus cannabinus L.) core or stalk, and the process variables were optimized by applying central composite design (CCD). The influences of carbonization temperature, duration of activation, and impregnation ratio on removal percentage of copper Cu(II) ions from aqueous solution and carbon yield were investigated. A quadratic model for adsorption percentage and a 2FI model for carbon yield were developed. The models were used to determine optimum process variables for production of activated carbon from the woody core of kenaf. From the analysis of variance (ANOVA), the most significant factor on each response of adsorption capacity and yield were identified. An activation temperature of (568±1)°C, activation time of 2.02 hours, and impregnation ratio of 1.75 were found as optimum production conditions. The experimental results showed excellent agreement with the predicted results obtained from a designed experiment that included the variables and responses of sorption capacity and yield. Textural properties of the prepared activated carbons were determined. The performance of the prepared activated carbon was further evaluated by fitting the equilibrium data with regression equations of Langmuir, Freundlich, and Temkin models at different temperatures. The research concluded that the prepared sorbent has good potential to remove Cu (II) ions from waste water. [ABSTRACT FROM AUTHOR]

This study investigated the effect of filler loading and coupling agent contents on the densities and mechanical properties of injection-molded foamed biocomposites. Biocomposite pellets were manufactured using wheat straw flour, maleic anhydrite grafted polyethylene (MAPE), paraffin wax, and high-density polyethylene (HDPE) with an extrusion process. Pellets and the chemical foaming agent (azodicarbonamide) were dry-mixed and foamed in an injection-molding machine. Densities and mechanical properties of the foamed biocomposites samples were measured and analyzed using central composite design (CCD). The results showed that both filler loading and coupling agent contents affected the density and mechanical properties of foamed biocomposites. Densities in the range of 0.57 to 0.81 gr cm-3 were achieved. Best results were obtained when less than 20% wheat straw flour and 1% coupling agent content were used. The flexural modulus and tensile modulus of foamed biocomposites were improved with increasing filler loading. However, flexural strength, tensile strength, elongation at break, and impact strength values were diminished. The tensile strength of the biocomposites was positively affected by CA contents, but other mechanical properties were not affected by it. Overall, injection molded foamed biocomposites with moderate mechanical properties were produced. [ABSTRACT FROM AUTHOR]

Cellulose nanofibril/phenol formaldehyde (CNF/PF) composite films with high work of fracture were prepared by filtering a mixture of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized wood nanofibers and water-soluble phenol formaldehyde with resin contents ranging from 5 to 20 wt%, followed by hot pressing. The composites were characterized by tensile testing, dynamic mechanical analysis, scanning electron microscopy, atomic force microscopy, thermo-gravimetric analysis, and moisture/water absorption. Neat CNF films had tensile stress and Young's modulus of 232 MPa and 4.79 GPa, respectively. PF resin was found to be well dispersed in the composites, although the resin increased the roughness of the film surfaces. Hygroscopic capacities of the composites were dramatically reduced, as compared to neat films, in both high humidity environments and when soaked in water. The composites exhibited slightly reduced tensile strength with modestly increased storage modulus compared to neat CNF films. Remarkably, the work of fracture ranged from 20 to 27 MJ/m³, making these films among the toughest reported for cellulose nanocomposites. [ABSTRACT FROM AUTHOR]

In this research, impregnated oil palm trunks (OPT) and polymer composites were prepared from a combination of dried oil palm trunks with phenol formaldehyde (PF) and urea formaldehyde (UF) resin in different resin percentages using an impregnation method. Time of impregnation was a parameter used to control the percentage of resin content in the oil palm trunks. These studies investigated the effect of resin content and types of resin on the physical properties of impregnated OPT. Water absorption tests revealed that OPT polymer composite with 75% PF resin loading had increases of 21% and 26% for OPT polymer composites with 75% UF resin loading. The thickness swelling of OPT polymer composites with 75% PF resin loading exhibited the lowest value of 3.30% as compared with OPT polymer composite with 75% UF resin loading, which exhibited a value of 4.30%. The dimensional stability of the OPT polymer composites with the highest resin loading was slightly lower when compared to rubberwood. Scanning electron micrographs show that PF resin placement in OPT polymer composites was better, and resin penetration retained the original dried OPT structure. [ABSTRACT FROM AUTHOR]

To investigate the effects of different ethylene vinyl acetate (EVA) contents on the performance of wood plastic composites (WPCs) made from poplar wood flour (PWF) and high density polyethylene (HDPE), physical properties tests, mechanical properties tests, and scanning electron microscope (SEM) tests were employed. The thermal stability and functional groups of PWF treated by EVA were evaluated by thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Fourier transform infrared spectroscopy (FTIR), respectively. The results showed that the hardness, water uptake, and thickness swelling of the WPCs was reduced with increasing content of EVA. The MOR and tensile strength of the WPC treated by 15% EVA content were enhanced by 17.48% and 9.97%, respectively, compared with those of the WPC without EVA. TGA results showed that the thermal stability of PWF treated by EVA was improved. FTIR analysis indicated that PWF was reacted and coated with EVA. SEM results showed that gaps and voids hardly existed in the sections of the WPCs treated by EVA. This research suggests that the flexibility and mechanical properties of WPCs could be improved by adding EVA. The best condition of EVA content could be 15%. [ABSTRACT FROM AUTHOR]