Physical,mechanical, and biodegradable properties of meranti wood polymer composites

In-situ polymerization and solution casting techniques are two effective methods to manufacture wood polymer composites (WPCs). In this study, wood polymer composites (WPCs) were manufactured from meranti sapwood by solution casting and in-situ polymerization process using methyl methacrylate (MMA) and epoxy matrix respectively. Physical, mechanical, and morphological characterizations of fabricated WPCs were then carried out to analyse their properties. Morphological properties of composites samples were analyzed through scanning electron microscopy (SEM). The result reveals that in-situ wood composite exhibited better properties compared to pure wood, 5% WPC and 20% WPC. Moreover, in-situ WPC had lowest water absorption and least biodegraded. Conversely, pure wood shown moderate mechanical strength, high biodegradation and water absorption rate. In term of biodegradation, earth-medium brought more severe effect than water in deteriorating the properties of the specimens.     

Tropical wood polymer nanocomposite (WPNC): The impact of nanoclay on dynamic mechanical thermal properties

In this study, wood polymer nanocomposites (WPNCS) were manufactured from five Malaysian tropical wood species by vacuum-impregnation attended by in situ polymerization using phenol–formaldehyde resin and montmorillomite nanoclay. Percentage weight gain and density of wood polymer nanocomposites depended on wood species. Thermo-mechanical properties of wood samples were investigated by the dynamic mechanical thermal analysis (DMTA) over the temperature range of −100 °C to 200 °C. The intrinsic properties of the components, morphology of the system and the nature of interface between the phases were also determined through DMTA test. Storage modulus (E′) of WPNC samples exhibited significant improvement over the temperature range, in both glassy region and rubbery plateau in relation to their corresponding raw wood samples and wood polymer composites (WPCs). Furthermore, damping (loss tan δ) peaks of all wood species were lowered by PF-Nanoclay system treatment, an indication of improved surface interphase of wood. Dynamic Young’s modulus (E_d) of wood was also calculated using free–free vibration testing. A significant increment was obtained for the PF-Nanoclay impregnated WPNC samples.     

Effects of wood constituents and content,and glass fiber reinforcement on wear behavior of wood/PVC composites

In flooring applications, experimental data and insight from scientific investigations on wear properties of wood/polymer composites (WPCs) are important for engineers to understand how to design and formulate WPC materials with high resistance to wear. In this work, three different types of wood flour – namely Xylia kerrii Craib & Hutch., Hevea brasiliensis Linn., and Mangifera indica Linn. – were utilized and incorporated into poly(vinyl chloride) (PVC) with a fixed content (10 phr) of E-chopped strand glass fiber. The physical, mechanical and wear properties, in terms of specific wear rate, were then assessed as a function of wood content and sliding distance. The experimental results suggested that the addition of wood flour increased the flexural modulus and strength up to 40 phr; beyond this concentration, the flexural properties decreased. Hardness was not affected by the addition of wood flour. The mechanical and wear properties of WPVC composites were found to improve with the addition of the E-glass fiber. Xylia kerrii Craib & Hutch. wood exhibited the lowest specific wear rate for non-reinforced WPVC composites, whereas Hevea brasiliensis Linn. wood showed the lowest specific wear rate for the glass fiber reinforced WPVC composites. The longer the sliding distance, the greater the specific wear rate in all cases.     

Effect of wood species on property and weathering performance of wood plastic composites

The effects of wood species on mechanical, thermal and accelerated weathering behaviors of high-density polyethylene based wood plastic composites (WPC) were investigated. The selected wood species are poplar, Douglas-fir, black locust, white oak, and ponderosa pine. Hybrid poplar and Douglas-fir based composite ranked highly in flexural properties. Thermogravimetric analysis indicated that thermal stability of the WPC is species dependent. The final decomposition of hemicelluloses in the hardwoods occurred at higher temperatures compared to that of softwoods. Color and chemical changes that occurred due to accelerated weathering were monitored using colorimetry and Fourier transform infrared spectroscopy. Weathered WPCs showed that color change and lightness increased with exposure time; degree of increase depends on wood species. WPC oxidation by weathering was assessed by carbonyl group concentration and was shown to increase with exposure. Hybrid poplar and ponderosa pine were shown to have good color stability among the wood species examined for WPC.     

Effects of chemical preservative treatments on durability of wood flour/HDPE composites

The main objective of this study was to determine the durability of chemical preservatives treated wood flour/high density polyethylene (HDPE) composites to white-rot fungus (Coriolus versicolor). Specimens, containing treated and untreated poplar wood flour (PF, 60%), were mixed with HDPE (38%) as polymer matrix and maleic anhydride grafted polyethylene (MAPE, 2 wt.%) as coupling agent. Two fungicide materials, namely 3-iodo-2-propynyl butylcarbamate (IPBC, 0.3, 0.6 and 0.9 wt.%) and 2 thiazol-4-yl-1H-benzoimidazole (TBZ, 0.3, 0.6 and 0.9 wt.%) were used in preparation of wood plastic composites (WPCs). Then, treated and untreated composites were exposed to the fungal decay for 12 weeks according to the European Union (EN) 113 standard. Mechanical and physical properties of the composites were evaluated before and after fungal incubation. The experimental results indicated that treated composites were more resistant to decay, with strength losses significantly lower than the untreated (control) sample. Physical properties in terms of water absorption and thickness swelling were improved by the incorporation of fungicide agents, but no significant differences were observed between the treaded samples. Weight losses for the various treated composites ranged from 1.1% to 4.5%. In addition, IPBC treated samples showed slightly lower weight loss compared with the treated composites with TBZ. The highest weight loss corresponds to the control. Accordingly, IPBC and TBZ can be effectively used as preservatives for WPC. However, IPBC showed superior results compared to the TBZ and it is recommended for the WPCs preservation.     

Effect of coupling agent and nanoclay on properties of HDPE,LDPE, PP,PVC blend and Phargamites karka nanocomposite

High density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and poly(vinyl chloride) (PVC) were solution blended by using a mixture of xylene and tetrahydrofuran as solvent and polyethylene-co-glycidyl methacrylate (PE-co-GMA) as compatibilizer. The minimum ratio of solvents to obtain a homogenous solution was optimised. Wood polymer composites (WPC) were prepared by using solution blended polymer, wood flour and nanoclay. X-ray diffraction studies of WPC treated with 1 and 3 phr nanoclay showed higher exfoliation compared to WPC treated with 5 phr nanoclay. TEM study also supported the above findings. FTIR studies indicated an interaction between wood, PE-co-GMA and clay. SEM study indicated an increase in miscibility among polymers due to addition of PE-co-GMA as compatibilizer. Thermal stability improved on addition of clay to the WPC. WPC treated with 3 phr clay showed highest mechanical properties. Hardness and water absorption were improved significantly with the addition of nanoclay to wood/polymer composite.     

Effects of hemicellulose extraction on properties of wood flour and wood-plastic composites

Hygroscopicity, low durability, and low thermal resistance are disadvantages of lignocellulosic materials that also plague wood-plastic composites (WPCs). Hemicellulose is the most hydrophilic wood polymer and is currently considered as a sugar source for the bioethanol industry. The objective of this research is to extract hemicellulose from woody materials and enhance the properties of WPC by diminishing the hydrophilic character of wood. Hemicellulose of Southern Yellow Pine was extracted by hot-water at three different temperatures: 140, 155, and 170 °C. Wood flour was compounded with polypropylene in an extruder, both with and without a coupling agent. Injection molding was used to make tensile test samples. The thermal stability of wood flour was found to have increased after extraction. Extraction of hemicellulose improved the tensile strength and water resistance of composites, which may indicate a decrease in the hygroscopicity of wood flour, better compatibility, and interfacial bonding of the filler and matrix.     

High density polyethylene and poly(ethylene terephthalate) in situ sub-micro-fibril blends as a matrix for wood plastic composites

Wood plastic composites were prepared based on in situ formed poly(ethylene terephthalate) (PET) sub-micro-fibril reinforced high density polyethylene (HDPE) matrices, using a two-step reactive extrusion technology. The use of ethylene-glycidyl methacrylate (E-GMA) copolymer improved phase compatibility in the sub-micro-fibril blends (SMFBs) with 75% HDPE and 25% PET. Most of in situ formed PET fibrils were less than 500 nm in diameter. The PET fibrils obviously increased mechanical properties of the blend, especially the moduli. The subsequent addition of 40 wt.% wood flour did not influence the size and morphology of PET fibrils, and the fibrils and wood fibers had a synergic reinforcement effect on composite properties. Compared with the HDPE/wood composites, the SMFB/wood system had 65% higher tensile strength, 95% higher tensile modulus, 42% higher flexural strength, and 64% higher flexural modulus, respectively. The technology offers a way to use engineering plastics (i.e., PET) for high performance WPC manufacturing.     

Influence of refiner fibre quality and fibre modification treatments on properties of injection-moulded beech wood–plastic composites

Thermo-mechanical pulp (TMP) fibres made from beech wood were produced using increasing refiner gap widths and thus with increasing fibre length and coarseness. Fibres (60% by weight) were compounded in an internal kneading mixer using high-density polyethylene as the matrix and injection-moulded. Fibre lengths and length/width ratios were determined (a) before processing and (b) after injection-moulding and Soxhlet extraction using the optical FibreShape system. An increase in fibre length resulted in a decrease in water absorption and an improvement in flexural strength and modulus of elasticity of the wood–plastic composites (WPC). However, flexural strength of the WPC with TMP fibres was not improved compared to WPC with wood flour when maleic anhydride-grafted polyethylene (MAPE) was used as a coupling agent. After injection-moulding, differences in length of the various TMP fibre types were minor. Fibre geometry before processing strongly influences the water absorption and flexural properties of the composite. Fibre treatment with emulsified methylene diphenyl diisocyanate (EMDI) resin before compounding was shown to be equally efficient in reducing water absorption and improving flexural strength as the addition of MAPE during the compounding step.     

A comparative study on the effects of Coriolus versicolor on properties of HDPE/wood flour/paper sludge composites

In this study, the effects of white-rot fungus (Coriolus versicolor) on the properties of high density polyethylene (HDPE)/wood flour/paper sludge composites were examined. In addition, the effectiveness of using coupling agent on the durability of decayed and undecayed WPCs was investigated. Two different types of sludge materials, namely paper making waste water sludge (PS) and ink-eliminated sludge (IES) were used. The mechanical properties, morphology, and water absorption of fabricated composites were investigated. At a similar wood flour loading, except for modulus of elasticity, the fungi treated composites showed lower mechanical properties (such as modulus of rupture and unnotched Izod impact strength), and higher water absorption compared to untreated composites. According to the results, addition of wood flour decreased the resistance of the composites to moisture and fungal environment. The exposure of the composites to a 4-cycle (2, 24, 48 and 72 h) water immersion caused serious damage to the interfacial adhesion between wood flour and polymer matrix due to contraction and swelling stresses developed during the cyclic exposure. The detrimental effect of fungal treatment on the water uptake of the composites could be explained by the degradation of lignin which made the cellulose content more accessible. Further, it makes chains of cavities that accelerate water absorption. However, the weight losses of all cases of treated composites were low (less than 2.5%), while PS filled composites were more susceptible to white-rot fungi. The addition of coupling agent during the compounding of wood flour and HDPE prevented the colonization and proliferation of fungus on the surface of the composites, and had an advantageous effect on the water uptake and mechanical properties of both treated and untreated composites.     

Die drawn wood polymer composites. II. Micromechanical modelling of tensile modulus

The Cox–Krenchel micromechanical model was applied to give predictions for the tensile moduli of isotropic and oriented wood polymer composites (WPC). The oriented WPC were produced by the Leeds die-drawing process using polypropylene filled with softwood and hardwood powders. The wood particles were extracted from the composites to determine their density and aspect ratio by dissolving in hot decalin. To measure particle shape and size, image analysis was employed. These experimental parameters were then introduced to the Cox–Krenchel model which was found to give prediction of tensile modulus in very good agreement with the experimental values.     

The utilization of bamboo charcoal enhances wood plastic composites with excellent mechanical and thermal properties

In order to enhance the mechanical properties and thermal properties of wood plastic composites (WPCs), bamboo charcoal (BC) was used as reinforcing filler of WPC, and a series of BC-WPC composites were prepared. The effect of BC and water treatment on water absorptions, morphologies, mechanical properties, the effect of water treatment on mechanical properties and thermal properties of the composites were investigated. The results showed that BC could have strong interfacial interaction in the WPC. The water resistance, flexural properties, tensile properties and thermal properties of BC-WPC were higher than WPC. The flexural and tensile properties were reduced and the impact strength was increased after water treatment. The presence of BC resists the influence of water absorption on composites mechanical properties.     

Effects of formulation variables on surface properties of wood plastic composites

Degree of surface quality of wood plastic composites (WPCs) is a function of both raw material characteristics and the manufacturing variables. The WPC panels comprised of different panel densities (800, 950, 1000, and 1080 kg/m³), wood flour contents (50, 60, 70, and 80 wt.%), wood flour sizes (<0.5, ?0.5 to <0.8, 0.8–1, and >1 mm), and hot-pressing temperatures (190 and 210 °C) were manufactured using a dry blend/flat-pressing method under laboratory conditions. The surface smoothness of the WPC panels improved with increasing WPC density, plastic content, and hot-pressing temperature while it deteriorated with increasing wood flour size. The reduction in the particle size of the WF resulted in a more compact structure on the WPC surface. In general, the wettability of the samples increased by increasing surface roughness.     

An experimental method for measurement of strain distribution between wood the flour particles and polymer matrix on micro-mechanical level

Wood plastic composites (WPCs) are comprised of wood flour and thermoplastic polymer. The matrix is typically high-density polyethylene, poly (vinyl chloride), or polypropylene. The effect of morphology and micromechanics of wood flour particles on the mechanical performance of the bulk composite is a relatively unexplored area. The knowledge about the in situ properties of wood particles and the interfacial properties between the wood particles and the polymer matrix in the bio-composites is very limited. The objective of this work is to characterize the full-field deformation and strain distribution in and around wood particles embedded in polymer matrix. The mechanical tests are performed in small-scale tensile loading stage on thin composite samples containing 1-3 wood particles orientated at various angles. The deformations and strains is measured using optical measurement system based on Digital Image Correlation (DIC) principle.     

Hydro and thermal stability of die drawn wood polymer composites in comparison to solid wood

Both isotropic and oriented wood polymer composites (WPC) based on 40% w/w of a softwood powder/hardwood powder and polypropylene (PP), together with solid pieces of wood, were subjected to water immersion and thermal expansion tests. Although generally die drawing increased the amount of water absorbed by the WPC by about 2-fold when compare to isotropic WPC, the oriented WPC exhibited extremely high hydro-dimensional stability. The values of the longitudinal and transverse swelling/shrinkage of the WPC oscillated only between 0 and −2.3% compared to values of between 4 and 14% for the solid woods. Incorporation of soft/hard wood powders into PP also substantially decreased its thermal expansion coefficient α in both the isotropic and the oriented states. This extremely positive effect was enhanced by increasing the draw ratio. In the longitudinal direction, α decreased from about 80 × 10⁻⁶ °C⁻¹ (for the isotropic PP) to 5 × 10⁻⁶ °C⁻¹ for the highly drawn PP filled with softwood.     

Effect of TiO2 and nanoclay on the properties of wood polymer nanocomposite

High density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and poly(vinyl chloride) (PVC) with Phragmiteskarka wood flour (WF) and polyethylene-co-glycidyl methacrylate (PE-co-GMA) was used to develop wood polymer composite (WPC) by solution blending method. The effect of addition of nanoclay and TiO₂ on the properties of the composite was examined. The exfoliation of silicate layers and dispersion of TiO₂ nanopowder was studied by X-ray diffractometry and transmission electron microscopy. The improvement in miscibility among polymers due to addition of compatibilizer was studied by scanning electron microscopy (SEM). WPC treated with 3 phr each of clay and TiO₂ showed an improvement in thermal stability. Mechanical, UV resistance and flame retarding properties were also enhanced after the incorporation of clay/TiO₂ nanopowder to the composites. Both water and water vapor absorption were found to decrease due to inclusion of nanoclay and TiO₂ in WPC.     

The effect of pre-softened wood chips on wood fibre aspect ratio and mechanical properties of wood–polymer composites

The objective of this work was to study the effect of chemical pre-treatment and moisture content of wood chips on the wood particle aspect ratio after compounding in a twin-screw extruder and on the mechanical properties of wood–polymer composites (WPCs). Composites with 50 wt.% wood content were manufactured using pre-treated and untreated wood chips. The effect of wood moisture content on composite properties was studied by using dried and undried wood chips. The mechanical properties and fracture surfaces of the composites as well as the microstructure and aspect ratio of wood particles after compounding were studied. The highest wood particle aspect ratio after extrusion was achieved by using pre-treated, undried wood chips as raw material. The chemical pre-treatment was found to enhance the defibration of wood chips as well as the mechanical properties of the composites.     

Effects of Daniella oliveri Wood Flour Characteristics on the Processing and Functional Properties of Wood Polymer Composites

The effects of particle sizes/distribution and contents on the processing, changes in microstructure and functional properties of wood polymer composites (WPCs) prepared from virgin high-density polyethylene (vHDPE) and sodium hydroxide (NaOH) treated Daniella oliveri wood flour via compression molding have been explored. Findings from this study suggested that an appropriate choice of wood flour characteristics could improve the interactions between the wood flour and the vHDPE matrix by eliminating incomplete wetting, segregation, and agglomeration of wood flour particles during processing while enhancing mechanical and thermal properties of the composites. Properties of the WPCs were optimized when wood flour of particle sizes/distribution and contents of +210–300 µm and 35 wt%, respectively, were blended with vHDPE matrix.     

Polybutene as a matrix for wood plastic composites

This study examined the feasibility of using polybutene-1 (PB-1), a ductile plastic, as a matrix for manufacturing wood plastic composites (WPCs) with improved toughness and ductility compared to currently commercialized WPCs. The processability, tensile, flexural, and impact properties of injection molded PB-1/wood-flour composite samples with varying proportions of wood flour were characterized. Analysis also included the morphology of fractured samples surface and adhesion between the polymer and wood flour using SEM. Comparisons of the mechanical properties and adhesion in the PB-1 composites to those of HDPE and PP-based WPCs found the composites made with PB-1 matrix significantly inferior in strength and stiffness (both in tensile and flexural) than their counterparts made of HDPE and PP matrices. In contrast, the processability, elongation at break, impact strength and adhesion in PB-1/wood-flour composites, superior to those of HDPE and PP, confirmed their suitability for use as a matrix in composites intended for applications subjected to high impacts.     

Mechanical,thermal expansion,and flammability properties of co-extruded wood polymer composites with basalt fiber reinforced shells

Basalt fiber (BF) filled high density polyethylene (HDPE) and co-extruded wood plastic composites (WPCs) with BF/HDPE composite shell were successfully prepared and their mechanical, morphological and thermal properties characterized. The BFs had an average diameter of 7 μm with an organic surfactant surface coating, which was thermally decomposed at about 210 °C. Incorporating BFs into HDPE matrix substantially enhanced flexural, tensile and dynamic modulus without causing a noticeable decrease in the tensile and impact strength of the composites. Micromechanical modeling of tensile properties for the BF/HDPE composites showed a good fit of the selected models to the experimental data. Compared to neat HDPE, BF/HDPE composites had reduced linear coefficient of thermal expansion (LCTE) values. The use of the pure HDPE and BF/HDPE layers over a WPC core greatly improved impact strength of core–shell structured composites. However, the relatively less-stiff HDPE shell with large LCTE values decreased the overall composite modulus and thermal stability. Both flexural and thermal expansion properties were enhanced with BF reinforced HDPE shells, leading to well-balanced properties of core–shell structured material. Cone calorimetry analysis indicated that flammability performance of core–shell structured composites was improved as the BF content increased in the shell layer.