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Due to a shortage of resources and a growing competition of land use, sustainable and efficient resource utilisation becomes increasingly important. The application and multiple, cascading utilisation of renewable resources is aimed at to ensure an allocation and future availability of resources. Wood polymer composites (WPCs) are a group of innovative materials consisting of mainly renewable resources. By means of summarizing recent research, it is shown how WPC can potentially contribute to an enhanced cascading utilisation. For the production of WPC, waste materials and by-products from wood and agricultural industry, e.g. offcuts, sawdust, residues from board manufacturing, pulping sludge, can serve as a raw material. Furthermore, the cited literature presents the use of recycled polymers and biopolymers as a potential alternative for the polymer component of WPC. By using biodegradable polymers, a fully biodegradable composite can be formed. In addition to using recycled materials and potentially being biodegradable, it is pointed out that WPC furthermore offers the possibility of being recycled itself, therefore being considered as a "green composite". Although the influence of contaminated waste streams and mixed filler and polymer types on the properties of WPC made with such recyclates is yet not fully understood and no collection systems exist for post-consumer WPC, in-house recycling on the production sites is identified as a promising option as it reduces production costs and enhances resource efficiency and cascading utilisation. On the basis of cited life cycle assessments, the eco friendliness of WPC is assessed resulting in the conclusion that WPC cannot compete with solid wood with respect to environmental impact but is an environmentally friendly alternative to neat plastics in several applications. [ABSTRACT FROM AUTHOR]

This study investigated the mechanical and thermal properties of hot press molded wood plastic composite (WPC) panels produced from different amounts (30, 40, or 50% weight) of Scots pine ( Pinus sylvestris L.) wood decayed by brown-rot fungi and polypropylene with coupling agent (maleic anhydride grafted polypropylene, 3 wt%). The results were compared with the properties of WPCs produced with the sound wood. The holocellulose content of the decayed wood was found to be significantly lower than that of the sound wood. Although the flexural and tensile properties of WPCs produced with the decayed wood flour were lower than those of the WPCs produced with the sound wood flour, their thermal stabilities were better at the wood flour levels of 40 wt% and 50 wt%. The weight loss of the WPCs produced with a high amount of decayed wood was lower than that of the WPCs produced with the sound wood, their enthalpy and crystallization degree were higher than those of the WPCs produced with the sound wood as well. [ABSTRACT FROM AUTHOR]

This work investigates the effects of different design parameters such as hemp content in the skins (10–40% wt.), layer thickness (1 and 2 mm), and foaming agent content in the core (0% wt., 0.6% wt. and 1.2% wt.) on the flexural properties of three layer sandwich panels of hemp and high density polyethylene produced by compression molding. The results show that hemp content was the most significant parameter for the flexural properties of these panels. In addition, it was found that specific modulus and strength (per unit weight) were 30% and 36% higher when using a foam core, respectively. [ABSTRACT FROM AUTHOR]

A comparative study the effect of the addition of silane coupling agents, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane on ethylenevinylacetate and Telinnemonspessulana flour composites was performed. The silane coupling agents were added in the mixing stage of ethylene vinyl acetate and wood flour (untreated and mercerized). Tests were also made by mixing ethylenevinylacetate with previously grafted wood flour. Flour graft was performed with vinyltrimethoxysilane and 3- aminopropiltrietoxisilano. The compounds were tested for tensile testing to evaluate the coupling agents. It was found that the addition of amino-silane during mixing increased tensile strength, being this an important result since these are lightweight materials that can be used in the construction and automobile industry. [ABSTRACT FROM AUTHOR]

We produced wood-plastic composite board by using sawmill wastage of mahogany ( Swietenia macrophylla) wood and low density polyethylene. We used multi-response optimization to optimize the process parameters of composite board production including mixing ratio, fire retardant (%) and pressing time (min). We investigated the effects of these three process parameters in the mechanical and physical properties of the composite board. Afterwards, Box-Behnken design was performed as response surface methodology with desirability functions to attain the optimal level of mixing ratio, fire retardant and pressing time (min). The maximum modulus of elasticity (MOE) and modulus of rupture (MOR) were achieved at the optimal conditions of wood plastic mixing ratio of 60:40, pressing time of 9 min and zero fire retardant percentage. The optimized MOR and MOE were 13.12 and 1,781.0 N mm, respectively. [ABSTRACT FROM AUTHOR]

In this study, the effects of two variable parameters namely nanoclay and coupling agent on the durability against fungal attack and water absorption of wood plastic composites (WPCs) were investigated. Composites based on high density polyethylene (HDPE), sanding dusts (SDs), and nanoclay (montmorillonite type) were made by melt compounding and then hot-pressing. Maleic anhydride grafted polyethylene (MAPE) was used as coupling agent. Treated and untreated (control) composites were exposed to the fungal decay using white-rot fungus (Trametes versicolor) for 4, 8, and 12 weeks according to the modified ASTM D 1413 standard. The experimental results indicated that the exposure of the composites to a five-cycle of boiling and drying caused serious damage to the interfacial adhesion between SDs and HDPE matrix due to contraction and swelling stresses developed during the cyclic immersion. The composites filled with nanoclay were more resistant than the control sample to decay. However, based on statistical analysis significant differences in water absorption of the composites were not observed after addition of nanoclay. In general, fungal degradation and water absorption were significantly decreased by the incorporation of MAPE. However, addition of 6 wt% MAPE improved both properties more than 3 wt% MAPE. Morphological studies showed fungal colonization and some micro voids, which accelerate water absorption. In conclusion, this work has shown that addition of nanoclay and coupling agent can considerably decrease fungal decay and water absorption of WPCs. [ABSTRACT FROM PUBLISHER]

Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface. [ABSTRACT FROM PUBLISHER]

The aim of this study was to evaluate and characterize various properties of experimental composition prepared from graphitic carbon nitride (g-C 3 N 4 ), wood flour (WF) and polypropylene (PP). g-C 3 N 4 with different concentrations (1 wt.%, 3 wt.%, 5 wt.% and 10 wt.%) were used as reinforcing filler for wood plastic compositions (WPCs). Maleic anhydride grafted polypropylene (PP-g-MA) was added as a coupling agent to increase the interaction between the components. Water absorption, morphology, physical, mechanical and thermal properties of the as-prepared composites were evaluated. The results showed that the tensile modulus of the composite was increased by 142.9% with increasing of g-C 3 N 4 contents to 5 wt.%, reaching approximately 498 MPa compared to WPC. Moreover, the flexural and tensile strengths reached their maximum values when the concentrations of g-C 3 N 4 were 1 wt.% and 3 wt.%, respectively. When maintaining the g-C 3 N 4 at a low concentration, it was well dispersed in the WPC with thin plate shape. However, when more g-C 3 N 4 (3–10 wt.%) was introduced, the enhancing effect began to diminish because of the agglomeration of g-C 3 N 4 which caused poor interfacial adhesion. The water absorption results showed a lower value with the addition of 1 wt.% g-C 3 N 4 , and the thermal tests showed that the degradation temperature shifted to higher value clearly after the addition of g-C 3 N 4 . Besides, with the addition of g-C 3 N 4 improved the outward color compared to the control sample. [ABSTRACT FROM AUTHOR]

The bending and tensile properties of polypropylene (PP) composites panels prepared from wood flour (50 wt%) or rice husk flour (50 wt%), PP (47 wt%) with coupling agent (maleic anhydride-grafted PP, 3 wt%), and aramid fabric were investigated. Three types of composite panels were produced using the aramid fabrics which were placed in single face layer, in core layer, or in two surface layers of the composite panels. The composite panels were manufactured using a dry blend/hot press (compression molding) method. The tensile and bending properties of the composite panels were greatly improved by the incorporation of aramid fabric. The composite panels having aramid fabrics positioned in two layers close to top and bottom layers had the highest bending and tensile properties, followed by one layer and core layer reinforcements, respectively. The tensile strength and modulus of wood flour-PP composites with the aramid fabric placed in the top and bottom layers were found to be 57.0 MPa and 5120 MPa while they were found to be 28.2 MPa and 3785 MPa for the wood flour-PP composites with the core layer of aramid fabric, respectively. The tensile strength and modulus of wood flour-PP composites without aramid fabric were found to be 12.5 MPa and 2540 MPa, respectively. Similar trends were observed for the rice husk flour-PP composite panels. [ABSTRACT FROM AUTHOR]

In the search of useful environmentally friendly fiber reinforced plastics, this is the first study that evaluates the capability to use natural pine rosin (in pure or maleated glycerol ester form) as a biodegradable coupling agent. Polypropylene as polymer matrix and discarded agave fiber (Agave tequilana) as reinforcing agent at different concentrations, were coupled with each one of the two rosins above mentioned; a commercial maleated polypropylene (Epolene, E-43) agent was used to compare their effect. As generic reference, composites without coupling agent were also tested. Mechanodynamic and mechanostatic tests clearly show an increment in mechanical properties of the composites, using any of the 3 coupling agents. The results obtained with maleated rosin were similar or slightly better than the ones obtained with the commercial agent for composites with high fiber content. Fiber content and coupling agent effect on composites crystallinity, was evaluated by differential scanning calorimetry. In addition, water absorption as a function of time was followed to evaluate the effect of surface modification, and FTIR analysis allowed the observation of the fiber-polymer matrix interaction that was promoted with the coupling agents. The effect of such interaction obtained with the different coupling agents, was observed by scanning electron microscopy. The results show the feasibility to use the natural pine rosin in pure or modified form as biodegradable coupling agents. [ABSTRACT FROM AUTHOR]

Dimensional stability of wood plastic composites (WPCs) made from polypropylene and pine wood flour with and without coupling agent was investigated. The pine wood flour was prepared from wood chips which had been immersed, respectively, in boiling water for 1 h, 3 h, and 5 h or in distilled water for 1 day, 3 days, and 5 days at room temperature. It was found that thickness swelling (TS) and water absorption (WA) of the WPCs made using extracted wood were lower than those of WPCs produced with unextracted wood. The TS and WA values of WPCs decreased with extraction duration both for cold and hot water extraction. The effect of hot water extraction on the TS and WA properties of the WPCs was more pronounced than cold water extraction. [ABSTRACT FROM AUTHOR]

This article presents the application of waste sanding dusts in order to evaluate its suitability as reinforcement for thermoplastics as an alternative to wood fibers. The effects of sanding dust loading and nanoclay content on the physical and mechanical properties were also studied. Overall trend showed that with addition of sanding dusts, tensile and flexural properties of the composites were significantly decreased, due to the reduction of interface bond between the fiber and matrix. It was found that flexural, tensile and withdrawal strength of fasteners were moderately enhanced by the addition of 2 wt% nanoclay in the matrix. However, with increase in the nanoclay content (4 and 6 wt%), the flexural and tensile properties decreased significantly. The results also showed that the withdrawal strengths of screws are much higher than those of nails. At certain amount of sanding dust, with increasing nanoclay loading the withdrawal strengths of fasteners (screws and nails) were considerably decreased. The thickness swelling and water absorption of the composites dramatically decreased with the increase in nanoclay loading. Except thickness swelling, both variable parameters (sanding dust and nanoclay contents) showed significant influence on physico-mechanical properties. [ABSTRACT FROM PUBLISHER]

Wood–plastic composites (WPCs) have been proposed as an alternative to natural wood due to their physical and mechanical properties. Development of these composites from natural fibers is receiving widespread attention partly because of growing environmental awareness. To dispose of produced waste from industry, low-value fiber resources could be converted into high-value products. This research studies the combination of polyvinyl chloride (PVC) to rubberwood (RBW) fiber, to palm oil trunk fiber, and to palm oil shell (POS) fiber. Composite performance optimization, material option comparison, basic engineering performance improvement, and durability of WPCs have been investigated. A two-stage process consisting of compounding and forming to produce WPCs using 40%–60% natural fiber reinforcements was carried out. Physical and mechanical properties of the WPCs were studied. The results showed that WPCs consisting of 60% RBW fiber and 40% PVC yielded the highest modulus of elasticity and modulus of rupture, which are approximately 90,130 MPa and 433 MPa, respectively. The ultimate compressive strength with a value of approximately 316 MPa was achieved from 60% POS fiber and 40% PVC. Reinforcing 40% POS fiber in 60% PVC exhibited the lowest water absorption rate. The overall result indicates an improvement of engineering performance, making better use of industrial wastes and indirectly assists environmental conservation endeavor along the process. [ABSTRACT FROM AUTHOR]

In this research, for the first time, the effects were investigated of nanoclay as a secondary reinforcement, titanium dioxide (TiO2) and hindered amine light stabilizer (HALS) as UV stabilizers on some properties of high density polyethylene (HDPE)/pistachio shell flour (PSF) composite as the new wood plastic composite (WPC). WPCs of HDPE/PSF with different levels of nanoclay (Cloisite 20A), TiO2 and HALS were prepared. Some properties were investigated before exposure to weathering conditions. Design of experiments (DOE) was carried out to find the best formulation and decrease the number of tests. WPC granules were prepared by melt-mixing method using a twin screw extruder, and then moulded using an injection moulding machine to prepare samples. The results of X-ray diffractometry (XRD) indicated partial exfoliation and intercalation of samples containing 3 and 6 per hundred composite (phc) of nanoclay. The tensile strength and modulus of HDPE/PSF samples containing 3 and 6 phc nanoclay showed 20% increase compared to samples without nanoclay. The presence of TiO2 and HALS in the formulation did not have a significant effect on tensile properties. The nanoclay presence in HDPE/ PSF formulation improved the water absorption resistance. [ABSTRACT FROM AUTHOR]

In this work, the influence of four variable parameters including fiber types (poplar and rice straw), fiber contents (45, 60, and 75 wt%), fiber sizes (20-40 and 40-60 mesh), and blending methods (hot-pressing and extrusion) on the physico-mechanical properties of wood plastic composite panels were studied. Generally, the results showed that each of the above-mentioned parameters had significant effect on the nail and screw withdrawal strength (pull-out load) and density, whereas their interactions did not have highly impressive effects on the properties. All tested properties vary significantly with fiber origin. Composites filled with larger fiber size, produced panels with higher withdrawal strength and density. The effect of blending method on density was maximal. Withdrawal strength values of each sample decreased with increase in fiber loading. The lowest withdrawal strength values of nail and screw were obtained from the samples filled with rice straw. It was found that strength properties of the composites can be improved moderately by adding 45 wt% fiber, 20-40 mesh particle and poplar flour. According to the results, the blending method is a significant variable in the determination of withdrawal strength. Therefore, the blending method can be recommended based on the end product applications. [ABSTRACT FROM AUTHOR]

The use of lightweight construction material with high corrosion resistance and low cost plays an important role in the design and construction of marine structures such as waterfronts. One of the most common methods for strengthening the structures is composite fibre reinforced plastic (FRP) sheet that is used for member retrofitting including wood plastic composite (WPC). The WPC material is produced from wood and compressed resin, which has good mechanical properties as well as economic benefits. The main problem of WPC reinforced with FRP sheets is the debonding of the sheet from WPC surface, which leads to premature and non-economic failure in members. One of the existing methods to solve this problem is surface preparation. However, surface preparation of wood plastic composite has some additional problems, such as operational cost, environmental pollution, etc. Therefore, to avoid debonding, another method has been used, known as the grooving method at the lower parts of beams. The laboratory used 50 I-shaped specimens with the same geometrical and mechanical properties. Initially, some slots such as longitudinal, transverse and diagonal grooves were created on the surface of specimens and filled by an epoxy. All beams were armed using one or two layers of GFRP sheets embedded at the lower part and were tested under four-point flexural loading. Grooves of different shapes, various widths and depths as well as the number of reinforcement layers were determined for considering their effect on the beam's behaviour. The results expressed that the debonding of FRP sheets can be delayed by selecting the longitudinal grooves with certain width and depth, which also leads to resistance improvement. [ABSTRACT FROM PUBLISHER]

This study was aimed at identifying the best approach of incorporating nano-graphene (NG) into bagasse/polypropylene composites to enhance their mechanical and physical properties. The composites with different NG contents were produced by melt compounding in a twin-screw extruder and then by injection molding. The mass ratio of the bagasse flour (BF) to polymer was 15/85 and 30/70 (w/w). Water absorption, thickness swelling, tensile strength, bending characteristics, impact strength and morphological properties of the produced composites were evaluated. In general, applying NG would improve mechanical properties of the composites. The mechanical test results indicated that when only 0.1 wt % of NG was added, tensile and flexural properties reached their maximum values, while the notched impact was slightly decreased. The composites containing 0.1 wt % NG and 30 wt % BF exhibited the highest tensile, flexural and notched impact strength values. Although incorporating NG into the polymer matrix effectively improves mechanical properties, this improvement comes at proper nanofiller loading (0.1 wt %). Addition of NG almost did not change the average water uptake and thickness swelling, compared to the control (without NG) samples. Morphological study confirmed that high contents (0.5-1 wt %) of NG were easily agglomerated. Thermal analysis showed slight increase in thermal stability of WPCs after incorporation of NG particles. In addition, it was found that the effect of BF was notable in material properties of the composites. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bamboo charcoal (BC) was used as reinforcing filler of wood-plastic composites. [•] BC could have strong interfacial interaction in the wood-plastic composites (WPCs). [•] The BC-WPC composites displayed lower water absorption properties. [•] The BC-WPC composites displayed higher flexural, tensile and thermal properties. [ABSTRACT FROM AUTHOR]

Mechanical and thermal properties of injection molded wood plastic composites (WPCs) were prepared from poplar wood flour (50 wt%), thermoplastics (HDPE or polypropylene) with coupling agent (3 wt%), and hegzagonal boron nitride (h-BN, 2, 4, or 6 wt%) nano powder were investigated. The flexural and tensile properties of WPCs significantly improved with increasing content of the h-BN. Unlike the tensile and flexural properties, the notched izod impact strength of WPCs decreased with increasing content of h-BN but it was higher than that of WPCs without the h-BN. The WPCs containing h-BN were stiffer than ones containing wood flour alone i.e., the partial replacement of h-BN with polymer had a synergistic reinforcing effect. The tensile elongation at break values of WPCs increased with the addition of h-BN. The differential scanning calorimetry (DSC) analysis showed that the crystallinity, melting and crystallization enthalpy of WPCs increased with increasing content of the h-BN. The increase in the crystallization peak temperature of WPCs indicated that h-BN was the efficient nucleating agent for on thermoplastic composites to increase the crystallization rate. Based on the findings obtained from the present study, it could be said that the optimum content of h-BN in the WPC for structural applications was 4 wt%. [ABSTRACT FROM AUTHOR]

The wood plastic composites studied in this work are composed of high-density polyethylene matrix and Pinus pinaster wood fibers. Despite some interesting intrinsic properties, this wood plastic composite has limited mechanical properties because of the incompatibility between the polar hydrophilic fibers and the non-polar hydrophobic matrix. In this study, the effects of maleic anhydride-modified polyethylene additive, of carbon chains grafted by acetylation and of wood fiber contents on the tensile mechanical properties of the wood plastic composite were studied. Tensile tests were carried out using digital image correlation as an intrusiveness and robust method for strain measurements. Results showed first that the addition of wood fibers made the wood plastic composite stiffer but less flexible. Acetylation improved the interfacial adhesion properties: the Young modulus was increased and a lower strain at failure was reported. The coupling agent also increased the compatibility but mainly in the case where there was no grafted chain. With regard to the carbon chains, the number of grafts improved the elastic properties while their length did not appear to have any influence. Finally, a scanning electron microscope was used to characterize the post-mortem morphology of the fracture surfaces, the results of which supported the observations obtained from the tensile mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the preparation and characterization of wood flour/polypropylene (PP) composites filled with graphene nanoplatelets (GNPs). The effects of GNPs, as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polypropylene (MAPP) was added as a coupling agent to all the composites studied. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurements indicated that when 0.8wt.% GNPs were added, tensile and flexural properties reached their maximum values. At high levels of GNPs loading (3–5wt.%), increased population of GNPs leads to agglomeration and stress transfer gets blocked. The addition of GNPs filler moderately increased the impact strength of composites. Addition of GNPs decreased the average water uptake and thickness swelling by 35% and 30%, respectively, compared to the control sample (without GNPs). It was observed that the composites filled with GNPs decomposed at higher temperatures compared to the pure PP and control. In all cases, the degradation temperatures shifted to higher values after the addition of GNPs. The improvement of physical and mechanical properties of composites confirmed that GNPs have good reinforcement and the optimum effect of GNPs was achieved at 0.8wt.%. [Copyright &y& Elsevier]

Barrier and mechanical properties of wood powder composites based on recycled polyethylene (RPE) were modified using a commercial nanoclay masterbatch. X-ray diffraction, dynamic rheology and thermogravimetric analysis measurements showed that nanoclay from the selected masterbatch was well dispersed and formed a percolation network in both virgin and RPEs. The resulting nanocomposites promoted the thermal stability of matrix significantly. Modification efficiency of nanoclay, however, was evidently influenced by the type of matrix, where the strongest effect was achieved in a low viscosity virgin high density PE. The masterbatch was incorporated into an industrial formula designed extrusion quality RPE/wood flour composite. Processing procedures, mainly compounding cycles, and material composition, mainly clay content and type of coupling agent, were optimised. Two extrusion cycles led to higher uniformity of resulting composites than one cycle. Addition of a coupling agent, which has medium viscosity and plenty functional groups, led to enhanced tensile strength. The twice compounded composites were well stiffened and strengthened via combination of 6 wt-% clay and medium viscosity coupling agent. All composites without the addition of nanoclay burned faster after ignition and dripped much earlier and more compared to the composites containing nanoclay even with as small amount as 3 wt-% and being compounded once. The material with 6 wt-% clay showed the best sample integrity and burned slowest of all the tested composites. Furthermore, no dripping during combustion was seen for this material. This study shows that the incorporation of nanoclay using the selected masterbatch can effectively improve the flame retarding properties of RPE based wood composites. [ABSTRACT FROM AUTHOR]

Wood plastic composite, known as green composite, combines natural vegetable fibers and plastic and thus acquires the properties of both. In this study, coir was subject to alkali treatment to eliminate pectin, hemicelluloses, fat and impurities. Alkali treatment reduces the weight of coir and the greater the concentration and longer the alkali treatment time, the greater is the loss of coir fibers. This study uses coir fibers and polypropylene to make wood plastic composite. Alkali treatment can increase the mechanical property of the resulting wood plastic composite. In particular, the optimum parameters of the treatment are 17.5 wt% for 1 h. As is demonstrated by scanning electron microscope images, methylmaleic anhydride-graft-polypropylene improves the interface binding force between the coir and polypropylene. [ABSTRACT FROM AUTHOR]

The objective of the present study was to observe the morphology and characterize the mechanical properties of wood plastic composite foams. Recycled high density polyethylene was mixed with Pinus radiata D. Don (radiata pine) wood fiber of 60 mesh. The fiber concentrations were 15 and 25% by weight. The compounds were foamed with a chemical agent ACA (azodicabonamide) and MAPE (Epolene E-20) was used as a coupling agent. The composites were obtained by twin-screw extrusion. The results showed that the coupling agent has a positive effect on the adhesion of the recycled polymer and wood fiber. The density of the compounds decreased with blowing agent and the mechanical properties of hardness, impact, modulus of elasticity in bending and tension were higher for unfoamed composites. It was concluded that increasing the concentration of fiber increases the mechanical properties with the exception of impact resistance of the compounds that by incorporating the blowing agent decreased slightly. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate dimensional stability and mechanical performance of Paulownia elongata wood flour filled polypropylene composites with and without maleic anhydride-grafted polypropylene (MAPP) at 30, 40, 50, and 60wt% contents of the wood flour. The thickness swelling and water absorption of the specimens increased with increasing wood content but these increments were significantly lower than thermoplastic composites filled with other fast growing woods such as eucalyptus and poplar. The modulus of elasticity in bending and tensile of the polypropylene composites improved with increasing the wood flour content while the bending, tensile, and impact strengths decreased. Adding the MAPP (3wt%) significantly improved the dimensional stability and mechanical properties of the composites. All WPC types had a higher melting temperature compared to neat polypropylene. Thermal stability of the polypropylene increased with increasing wood flour content. The test results showed that P. elongata wood is an efficient reinforcing filler for thermoplastic composites in applications requiring high dimensional stability. [Copyright &y& Elsevier]

The sound transmission loss (STL) of precipitated calcium carbonate (PCC)-filled wood plastic composite (WPC) was studied using a numerical analysis method based on the mass law and sound scattering theory. Several physical models for explaining sound wave transmission in WPC were established, and relevant STL equations were derived. The STL of WPC filled with different PCC weight ratios was analyzed using these models. The results showed that the STL of WPC increased with an increase in sound frequency and PCC weight ratio. The improvement of sound insulation was attributed to the mass increase, sound scattering enhancement by the fillers, and PCC weight ratio. The predicted results showed similar trends to the experimental data under the same processing conditions. It was concluded that the proposed models can be used to analyze the STL of filled WPC. Larger inorganic particle size led to higher STL, but its effect was not obvious at lower frequency ranges. Predicted STL increased with increased weight ratio of wood for the whole frequency range tested. [ABSTRACT FROM AUTHOR]

The sound transmission loss (STL) of precipitated calcium carbonate (PCC)-filled wood plastic composite (WPC) was studied using a numerical analysis method based on the mass law and sound scattering theory. Several physical models for explaining sound wave transmission in WPC were established, and relevant STL equations were derived. The STL of WPC filled with different PCC weight ratios was analyzed using these models. The results showed that the STL of WPC increased with an increase in sound frequency and PCC weight ratio. The improvement of sound insulation was attributed to the mass increase, sound scattering enhancement by the fillers, and PCC weight ratio. The predicted results showed similar trends to the experimental data under the same processing conditions. It was concluded that the proposed models can be used to analyze the STL of filled WPC. Larger inorganic particle size led to higher STL, but its effect was not obvious at lower frequency ranges. Predicted STL increased with increased weight ratio of wood for the whole frequency range tested. [ABSTRACT FROM AUTHOR]

Abstract: Sliding friction behavior plays a critical role in diverse systems to determine the serviceability of end-used wood products, such as safety. The kinetic or dynamic coefficient of friction (μk ) is used to describe the relative motion between two objects, which is highly dependent on the material characteristics and surface topology. It has been discovered that the relationship between friction force and sliding time is a kind of regular/chaotic ‘stick–slip’ or random motion, i.e. nonlinear. However, studies on the nonlinear friction behavior of modified wood products are very limited. This study was aimed at providing a deep understanding of the kinetic friction behavior of wood decking products, including Chromated Copper Arsenate (CCA) treated spruce lumber (CCAS), heat-treated spruce lumber (HTS), wood plastic composite (WPC) lumber and untreated spruce lumber (UTS) as a control group. The authors extended their previous research on the evaluation of slip resistance of modified wood decking products in terms of static coefficient of friction (μs ). The experimental design included four types of specimens (CCAS, HTS, UTS and WPC), two surface conditions (dry and wet), three sliding speeds (10, 50 and 250mm/min), and two weights of sliding block (14 and 20kg). The testing set up was in accordance with ASTM D2394 “Standard methods for simulated service testing of wood and wood-base finish flooring”. It was found that (1) ‘stick–slip’ motion only occurred when a 20kg sliding block moved at a speed of 10mm/min on the dry surface of CCAS, HTS, and UTS specimens, while under the rest conditions, a random motion was found. However, only the random motion was observed under all conditions for WPC specimens; (2) the average μk values of all types of specimens under wet surface condition were larger than those under dry surface condition. The μk values of WPC specimens were the lowest among four types of specimens, followed by UTS, and then HTS and CCAS; (3) the ratios of μk to μs of CCAS, HTS, and UTS specimens ranged from 0.70 to 0.85, while those of WPC specimens varied between 0.40 and 0.50; and (4) good linear correlations between μk and μs were found in modified wood products tested. [Copyright &y& Elsevier]

Wood plastic composite (WPC) of wood flour (WF), high density polyethylene (HDPE), maleic anhydride-grafted polyethylene (MAPE) and lubricant was prepared by extrusion, and then exposed to different temperatures to evaluate the effects of freezing and thermal treatment on its dimensional and mechanical properties. At elevated temperatures, WPC expanded rapidly initially, and then contracted slowly until reaching an equilibrium state. Treatment at 52°C and relative humidity of 50% for 16 days improved the mechanical properties of WPC: flexure, tensile strength, and izod unnotched impact strength increased by 8%, 10% and 15%, respectively. Wide-angle X-ray diffraction (XRD) tests showed that the degree of crystalization of HDPE in WPC declined with increasing treatment temperature. [ABSTRACT FROM AUTHOR]

In this research, effect of nanoclay (Cloisite10A), coupling agent (MAPE), spruce sawdust and electron beam irradiation dose on mechanical and water absorption properties of sawdust-low density polyethylene nanocomposite are investigated. Design of the experiments (DOE) is performed by the statistical Taguchi method. The XRD analysis depicts partially intercalated/exfoliated nanocomposites. The findings reveal that increasing cloisite10A concentration from 2.5 to 7.5 wt % has improved the tensile and bending strengths and modulus also water diffusion coefficient is reduced. Increase the sawdust content from 40 to 60 wt % not only markedly increases the tensile and flexural properties but also increases water diffusion coefficient and reduces toughness significantly. Electron beam irradiation dose of 60 kGy improves the tensile and flexural properties and decreases water diffusion coefficient. The SEM micrographs confirm a suitable coherence between lignocelluloses filler phase and low density polyethylene matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Wood plastic composite (WPC) boards are an emerging engineered wood composite that is a substitute for solid wood and other wood composite materials used for exterior applications, primarily decking. We are interested in understanding the strength of these boards and estimating the lower percentiles of failure under perpendicular pressure. The strength of WPC is determined by the perpendicular pressure required to permanently deform a board (modulus of elasticity, MOE) and the perpendicular pressure required to rupture the board (modulus of rupture, MOR). Two WPC production-size extrusion lines at the same facility are compared in this article by comparing the distributions of pressure to failure for samples of WPC extruded from each line. Parametric bootstrapping is used to calculate confidence intervals of the 1st, 5th, and 10th percentiles of the MOE and the MOR from each line. Furthermore, both parametric and nonparametric bootstrapping are performed to estimate confidence intervals on the differences between the two lines for the 1st, 5th, and 10th percentiles of the MOE and the MOR. A statistical difference between the strength of the WPC extruded from the two lines is found in the MOR. [ABSTRACT FROM AUTHOR]

Wood-plastic composites (WPC) have many applications as structural and non-structural material. As their outdoor application becomes more widespread, their resistance against weathering, particularly ultraviolet light and biodegradation becomes of more concern. In the present study, natural fiber composites (NFPC) made of bagasse and high density polyethylene, with and without pigments, were prepared by extrusion and subjected to accelerated weathering for 1440 h; then weathered and un-weathered samples were exposed to fungal and termite resistance tests. The chemical and surface qualities of samples were studied by ATR-FTIR spectroscopy, colorimetry, contact angle, and roughness tests before and after weathering. Using bagasse as filler does reduce the discoloration of weathered samples. Adding pigments may reduce the effect of weathering on lignin degradation, although it favors polymer oxidation, but it increases the weight loss caused by fungi. Despite the high resistance of samples against biological attack, weathering triggers attack by termites and fungi on the surface and causes surface quality loss. [ABSTRACT FROM AUTHOR]

Biological durability is an important feature for wood-plastic composites (WPC) intended for outdoor applications. One route to achieving WPC products with increased biological durability is to use wood preservative agents in the formulation of the WPC. Another option could be to use a chemically modified wood component that already exhibits increased resistance to biological degradation. There is also a need to use biobased thermoplastics made from renewable resources, which would decrease the dependency on petrochemically-produced thermoplastics in the future. The objective of this study was to examine moisture sorption properties, biological durability, and mechanical performance of injection-molded WPC samples based on acetylated or thermally modified wood components and a polylactate matrix. The biological durability was evaluated in a terrestrial microcosm (TMC) test according to ENV 807, followed by mechanical evaluation in a center point bending test. The moisture sorption properties were investigated via both water soaking and exposure in a high-humidity climate. Low or negligible mass losses were observed in the TMC test for all WPC samples. However, the mechanical evaluation after exposure in the TMC test showed 35-40% losses in both strength and stiffness for the WPC containing an unmodified wood component. [ABSTRACT FROM AUTHOR]

Summary: This study has tried to use HDPE and the coupling agent consistent MAPP and cornstalk fibers, create wood plastic composite material and its physical and mechanical properties such as tensile modulus, flexural modulus and humidity absorption is measured. After determining the percentage of 20, 30 and 40% of corn stalk fibers in the product and the use of two longitudinal mesh levels of 40 and 80 of them and using the 5% MAPP coupling agent testing was done and it was shown that increasing fiber length and percent increase in product humidity is absorbed. This is while the declines by increasing the fiber length changes of samples were during the tensile tests. In the bending test also increased fiber length and flexural modulus was increased. [ABSTRACT FROM AUTHOR]

Abstract: With increasing global concerns on environmental issues, Chromated Copper Arsenate (CCA) treated wood decking products have been step by step replaced by Wood Plastic Composite (WPC) lumber and heat-treated lumber. The slip resistance of decking is no doubt a critical safety index. Overall, there has not been a proper standard for measuring the slip resistance of WPC products. Canadian Construction Materials Centre (CCMC) uses the static coefficient of friction (μs ) to evaluate the slip resistance of WPC products, which stipulates that μs should be larger than 0.50. This study was aimed at measuring the slip resistance of WPC decking products in terms of μs and then comparing with others. There were four types of testing specimens including WPC lumber (WPC), CCA treated spruce lumber (CCAS), heat-treated spruce lumber (HTS) and untreated spruce lumber (UTS). μs was measured, according to ASTM D2394 standard, under two surface conditions (SCs) (dry and wet), two weights of sliding block (WSB) (14 and 20kg), and three sliding speeds (SSs) (10, 50 and 250mm/min). It was discovered that (1) The μs values of CCAS and HTS were always larger than those of UTS and WPC, and only at some specified testing conditions, the μs values of them could reach or exceed 0.50; (2) The μs values of all specimens under wet SC were larger than those under dry SC, and the increase of μs under wet SC was less significant than that under dry SC as the WSB increased from 14 to 20kg; (3) The μs values increased, regardless of the types of specimens, with increasing the WSB from 14 to 20kg; (4) There was no statistically significant difference in μs among three SS values used, 10–50 or 250mm/min. [Copyright &y& Elsevier]

Abstract: Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites incorporated with different contents of boron compounds; borax/boric acid and zinc borate, and phosphate compounds; mono and diammonium phosphates were investigated. The effect of the coupling agent content, maleic anhydride-grafted polypropylene, on the properties of the composites with fire-retardant was also investigated. The composites with the zinc borate had the highest dimensional stability and strength in the bending, tensile, and izod impact, followed by the monoammonium phosphate, borax/boric acid, and diammonium phosphate treatments. The treatments produced modest improvements in fire performance as indicated by reductions in the heat release rates. Best results were achieved with the phosphate treatments. The Scanning Electron Microscope–Energy Dispersive Spectroscopy elemental mapping of the samples revealed that the outer surface of the wood fibers was coated by some crystalline deposits of the fire-retardants. [Copyright &y& Elsevier]

This article presents a study on the rheological behavior of wood plastic composites with a mathematical approach to acquire their melt constitutive equation. The wood plastic composites were produced with four compositions of high density polyethylene as the matrix and very fine wood particles, smaller than 50 µm in size, as the fillers: 40, 50, 60 and 70 wt% of wood content. Storage modulus (G′), loss modulus (G′′), complex viscosity (η*) were measured for all four composites at a temperature of 170°C and for shear rates in the range of 1–500 rad/s. The results indicated a noticeable increase in all measured properties upon increasing the wood content. In mathematical approach, the main goal was to obtain the most fitted expression to relate shear stress with shear rate. Firstly power law model was applied considering a viscous behavior of the composites. In continue, generalized Maxwell model was used and the most fitted number of the elements in modeling was analyzed for various wood contents. Moreover, Cox–Merz rule was evaluated for the composites, where it showed that this rule is only valid for the composites in some special conditions. [ABSTRACT FROM PUBLISHER]

The tensile behavior of wood–plastic composite (WPC) with or without additive is studied using full-field strain measurements by 3D digital image correlation. It is shown that macroscopic values of the longitudinal strain are close to those measured by mechanical extensometer using standard mechanical tests. The modulus of elasticity provided by a Maxwell–Bingham model fitted to the experimental tensile curves is analyzed for several WPC formulations depending on the wood contents and the presence of additive. Color maps of the spatial strain distribution are commented. Moreover, the damage behavior and the degree of heterogeneity are analyzed thanks to the spatial standard deviation of the longitudinal strain field. [ABSTRACT FROM PUBLISHER]

Coconut fiber-filled composites based on PVC/ASA blend were developed. The results reveal that the impact strengths of the PVC/ASA/coconut fiber composites are significantly higher than those of PVC wood composites or polyolefin wood composites when comparison was made at the same fiber content. Dynamic mechanical analysis thermograms exhibit two distinct glass transition temperatures (Tgs) of the blend matrix, indicating partial miscibility of the blends. The storage modulus at room temperature and Tgs of the composites systematically increase with the fiber content. The tensile strength value of the blend as high as 45 MPa was obtained and found to only slightly decrease with the fiber content. The PVC/ASA blend shows a potential use as a matrix of high-impact wood composite products with good thermal dimension stability due to the outstanding impact strength and thermal properties of the blend. [ABSTRACT FROM PUBLISHER]

Abstract: The water absorption behavior and durability of extruded wood polypropylene composite (WPC) material used in Z-section sheet piles was investigated. An experimental technique to determine percentage water absorption and its effect on mechanical properties was implemented. Water absorption tests were carried out on specimens cut from flanges and webs of the Z-section by immersion in tap water at 21, 45 and 70°C. Freeze–thaw resistance of saturated composites was studied by cycling temperatures in the range of 21 to −29°C. The absorption behavior followed the kinetics of a Fickian diffusion process. This behavior was modeled using an analytical solution based on Fick’s second law of diffusion. Quasi-static bending tests were conducted periodically on specimens immersed in water to assess degradation in flexural properties. A significant decrease in mechanical properties of the water-saturated specimens compared to the dry control was observed. Degradation of flexural modulus was found to be a strong function of water absorption with initial decrement as percentage water absorption increased and finally stabilized as the absorption process approached saturation. However, freeze–thaw cycling did not have any significant effect on mechanical properties of saturated composites. A phenomenological model for moisture intrusion and its effect on mechanical properties was implemented and applied to explain the experimental findings. [Copyright &y& Elsevier]

Surface roughness and wettability of flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) (5, 10, or 15% by weight (wt)) at 50 wt-% content of the wood flour (WF) were investigated. The most common FRs, zinc borate (ZB), magnesium hydroxide (MH), and ammonium polyphosphate (APP), were used in the experiments. The WPC panels were made from dry-blended wood flour (WF), fire retardant (FR) powder, and polypropylene (PP) powder with maleic anhydride-grafted PP (2 wt-%) formulations using a conventional flat-pressing process under laboratory conditions. The contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Three roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the WPC panel surface using a fine stylus tracing technique. It was found that the surface smoothness of the WPC panels decreased with increasing content of the FR powder while the wettability increased. The control WPC panel without the FR had the smoothest surface, followed by the WPC panels containing the MH, ZB, and APP, respectively. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to enhance the dimensional stability of flat-pressed wood plastic composites (WPCs) containing fast growing wood fibres by a thermal-treatment method. The wood fibres were treated at three different temperatures (120, 150, or 180 °C) for 20 or 40 min in a laboratory autoclave. The WPC panels were made from dry-blended Eucalyptus camaldulensis wood fibres and polypropylene (PP) powder (50:50 by weight) using a conventional flat-press process under laboratory conditions. Thickness swelling and water absorption of the WPC panels significantly decreased with increasing the treatment temperature and time. The thermal-treatment of eucalyptus wood fibres slightly decreased the screw withdrawal resistance of the WPC panels as compared to the reference panels while the flexural properties and internal bond strength were more seriously affected by the treatment. The present study revealed that the thermal-treatment of the wood fibres significantly improved the dimensional stability of the WPC panels. [Copyright &y& Elsevier]

Abstract: A cradle-to-grave life cycle assessment was done to identify the environmental impacts related to alkaline copper quaternary (ACQ)-treated lumber used for decking and to determine how the impacts compare to the primary alternative product, wood plastic composite (WPC) decking. A model of ACQ-treated lumber life cycle stages was created and used to calculate inputs and outputs during the lumber production, treating, use, and disposal stages. Lumber production data are based on published sources. Primary wood preservative treatment data were obtained by surveying wood treatment facilities in the United States. Product use and disposal inventory data are based on published data and professional judgment. Life cycle inventory inputs, outputs, and impact indicators for ACQ-treated lumber were quantified using functional units of 1000 board feet and per representative deck (assumed to be 320 square feet (30 square meters) of surface decking material) per year of use. In a similar manner, an inventory model was developed for the manufacture, use, and disposal of the primary alternative product, WPC. Impact indicator values, including greenhouse gas (GHG) emissions, fossil fuel use, water use, acidification, smog forming potential, ecological toxicity, and eutrophication were quantified for each of the two decking products. National normalization was done to compare the significance of a representative deck surface per year of use to a family’s total annual impact footprint. If an average U.S. family adds or replaces a deck surfaced with ACQ-treated lumber, their impact “footprint” for GHG emissions, fossil fuel use, acidification, smog forming potential, ecological toxicity, and eutrophication releases each is less than one-tenth of a percent of the family’s annual impact. ACQ-treated lumber impacts were fourteen times less for fossil fuel use, almost three times less for GHG emissions, potential smog emissions, and water use, four times less for acidification, and almost half for ecological toxicity than those for WPC decking. Impacts were approximately equal for eutrophication. [Copyright &y& Elsevier]

The microstructure of wood plastic composite (WPC) with respect to wood particle content and maleic anhydride-grafted polypropylene (MAHPP) compatibilizer is studied by both linear and nonlinear rheological methods in this article. The complete long characteristic relaxation behavior in linear region, which is closely related to the structure of wood particle aggregates and MAHPP compatibilizing effect at the interface, is limited by observing time. Fortunately, the Fourier transform rheology (FTR) by the stress control mode is found to be an effective method for further investigating the structure with long relaxation time in WPC system. The plateau value of I at high stress and the range of ϕ are proved to be corresponding to the content of wood particle agglomerates in the WPC melts and the type of interfacial hydrodynamic interaction. The interesting outcomes suggest that MAHPP do has the effect on changing the properties of the heterogeneous interface and confirm the difference of the structure with long relaxation time in WPC can be easily captured by the high sensitive FTR indeed. [ABSTRACT FROM AUTHOR]

Wood plastic composite (WPC) development has been facilitated by the economical extrusion of WPC profiles for various applications. The physical and mechanical properties of WPC products can be optimized by regulating extrusion processing conditions and material formulations. Rectangular WPC profiles were produced with varied high-density polyethylene (HDPE), wood fiber (WF), and lubricant contents under different extrusion conditions in a twin-screw extruder extrusion line. Optimal tensile and flexural properties were obtained with 50 wt% WF at 7 and 3 wt% lubricant and maleated polyethylene (MAPE) contents. The apparent shear viscosity of the WPC melts decreased gradually with increased lubricant content. Hence, for practical applications, a combination of HDPE grade, WF, lubricant, and MAPE contents can provide the benefits of lower shear viscosity while maintaining the mechanical properties and surface smoothness of WPC profiles. [ABSTRACT FROM PUBLISHER]

Abstract: Wood plastic composite (WPC) beams retrofitted with carbon and glass fiber-reinforced polymer (CFRP and GFRP) composites offer an attractive solution to enhance the behavior of wood in terms of strength and ductility, as well as altering the mode of rupture of such structural members. However, very little is known about their performance. Thus, this paper presents a theoretical model based on nonlinear WPC properties, to investigate the behavior of hybrid WPC–FRP beams. In order to calculate the bending moment, the model considers an exponential function in the stress–strain diagram of WPC in both tension and compression parallel to the fibers. A four-point bending test configuration was conducted as short-term experiments to determine the load–displacement relationships of WPC beams with CFRP and GFRP sheets adhered to the tensile side. In order to validate the employed approach, the results obtained from the theoretical model were compared with the experimental results where a satisfactory agreement was achieved. [ABSTRACT FROM AUTHOR]

This study evaluated physical and mechanical properties of the wood plastic composite panels made from dry-blended rubberwood fiber-polypropylene (PP) powder formulations using a conventional flat-press process under laboratory conditions. Three levels of rubberwood fibers (Hevea brasiliensis), 40%, 50%, and 60% based on the composition by weight, were mixed with the PP powder without and with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. Water resistance of the panels was negatively influenced by the increasing wood fiber content. The modulus of rupture of the panels significantly increased with the increase in the wood fiber content from 40 to 50 wt% and then decreased as the fiber content reached 60 wt% but this decrease was not significant. The modulus of elasticity of the panels increased with the increase in fiber content from 40 to 60 wt%. Internal bond strength and screw withdrawal resistance declined with the increase in fiber content from 40% to 60 wt%. The formulations with MAPP were found to have higher strength and better water resistance. [ABSTRACT FROM AUTHOR]