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The anisotropy and nonuniformity of wood-plastic composites (WPCs) affect the milling tool, which rapidly wears during high-speed milling of WPCs. Thus, the evolution mechanism of tool failure becomes complicated, and the prediction of tool wear cannot be precisely described mathematically. A neural network based on tool wear test was proposed to predict the tool wear condition during high-speed milling of WPCs. The traditional backpropagation (BP) neural network easily falls into the local optimal solution. A genetic algorithm (GA-BP) neural network prediction model was established by using the GA to optimise its initial weight and threshold. The BP model and the GA-BP model were evaluated in terms of mean square error and training times, and the generalisation verification was applied to the prediction model. After analysing and comparing the results of the two models, the GA-BP neural network model has better training speed and accuracy under the test conditions. The relative error between the predicted value and the actual value is controlled within 5%. [ABSTRACT FROM AUTHOR]

Although applications of wood-plastic composites (WPC) have rapidly increased, the raw materials used for producing WPC are still sound wood until now. The decayed wood usually is discarded or used as fire wood, which causes a serious waste of resources and environmental pollution. However, the decayed wood contains high lignin content which can be used for producing polymeric materials. In this study, decayed wood plastic composites (DWPC) with nano calcium carbonate (NCC), activated carbon (AC) and chitosan (CS) were fabricated and sound wood plastic composites (SWPC) without any additive were prepared. Compared to the results of physical and chemical properties of DPWCs with SWPCs, it was found that the mechanical properties, chemical structure, thermal stability, degree of crystallinity (Cr) and flame retardancy of DWPC with CS were better than DWPC without any additive, and even better than SWPC. The addition of CS (4%) to decayed wood powder (about 30%) and PVC (about 70%) could improve the physical, chemical, and bonding properties of DWPC, which could reach the level of sound wood plastic composites. The results of this work proposed a novel green strategy for utilizing decayed wood for making polyvinyl chloride/wood flour composites.

Outdoor building materials made of wood require preservatives containing chromated copper arsenate and other carcinogenic substances but still are subject to decay, hence they need to be replaced every few years. Wood-plastic composite (WPC) is an environmental-friendly composite of wood flour/fiber reinforced thermoplastic polymers (i.e., plastic). As WPC is made of plastic to evenly cover the wood flour, it has a lower moisture content than wood. In this study, maleic anhydride grafted polyolefin elastomers (POE-g-ma) and methyl methacrylate-butadiene-styrene copolymer (MBS) were used as impact modifiers to prepare WPCs from recycled polyethylene terephthalate (rPET) and recycled polyamide 6 (rPA6) blends (PET/PA6). The thermal properties of the WPCs with different mixing ratio polymer blends of rPET to rPA6 (E60/A40, E50/A50, and E40/A60) were investigated, as well as their mechanical properties after accelerated weathering. In addition, the creep behavior of the E40/A60 WPC under different environmental conditions was investigated. During the 10-h creep test, the POE-g-ma/WPC strain varied significantly more than MBS/WPC under environmental aging and higher loadings. The test results of impact and creep also show that the toughening effect of POE-g-ma/WPC was slightly better than that of MBS/WPC. In summary, the higher PET content resulted in lower flowability and a higher initial decomposition temperature, with the E60/A40 WPC having better anti-aged mechanical properties and more suitable for outdoor building applications. [ABSTRACT FROM AUTHOR]

The purpose of this study is to compare the characteristics of wood–plastic composites (WPCs) made of polypropylene (PP) and wood fibers (WFs) from discarded stems, branches, and roots of pomelo trees. The results show that the WPCs made of 30–60 mesh WFs from stems have better physical, flexural, and tensile properties than other WPCs. However, the flexural strengths of all WPCs are not only comparable to those of commercial wood–PP composites but also meet the strength requirements of the Chinese National Standard for exterior WPCs. In addition, the color change of WPCs that contained branch WFs was lower than that of WPCs that contained stem or root WFs during the initial stage of the accelerated weathering test, but the surface color parameters of all WPCs were very similar after 500 h of xenon arc accelerated weathering. Scanning electron microscope (SEM) micrographs showed many cracks on the surfaces of WPCs after accelerated weathering for 500 h, but their flexural modulus of rupture (MOR) and modulus of elasticity (MOE) values did not differ significantly during weathering. Thus, all the discarded parts of pomelo trees can be used to manufacture WPCs, and there were no significant differences in their weathering properties during 500 h of xenon arc accelerated weathering.

In this paper, we exclusively studied the effects of dry and wet pulverization of different wood flours on the fatigue performance of polypropylene (PP)/wood flour (WF) composites. Wood flours obtained from cypress and Scots pine trees were pulverized in both dry and wet conditions at two different mill-plate gaps, 200 Ām and 350 Ām, and were used as reinforcement in PP matrices. Master batches of PP with different types of pulverized WF were compounded before processing in an extruder. The PP/WF composites of initial WF were also prepared for comparison. The prepared composites were analyzed by tensile and fatigue tests. It was found that the tensile properties of wood/polypropylene composites were affected by the pulverization of WF. Fatigue test results displayed that wet pulverization of short cypress flour had a negative effect on the fatigue life of PP/WF composites, while wet pulverization of long cypress flour and pine flour had a positive effect on the fatigue life of PP/WF composites. [ABSTRACT FROM AUTHOR]

The impact of wood waste on the mechanical and biological properties of silicone-based composites was investigated using wood waste from oak, hornbeam, beech, and spruce trees. The density, abrasion resistance, resilience, hardness, and static tensile properties of the obtained WPC (wood–plastic composites) were tested. The results revealed slight changes in the density, increased abrasion resistance, decreased resilience, increased hardness, and decreased strain at break and stress at break compared with untreated silicone. The samples also showed no cytotoxicity to normal human dermal fibroblast, NHDF. The possibility of using prepared composites as materials to create structures on the seabed was also investigated by placing samples in a marine aquarium for one week and then observing sea algae growth.

Ar:O2 low pressure plasma (Ar:O2 LPP) surface treatment is proposed for increasing the surface energy and improve the adhesion of wood-polyethylene composite. The treatment time was varied between 20 and 90 s and the configuration of the shelves inside the plasma chamber (direct and secondary downstream) was also changed. Ar:O2 LPP treatment during 30-40 s created new surface carbon-oxygen groups, increased the surface energy, mainly its polar component, reduced roughness and caused ablation of wood-polyethylene composite, irrespective of the configuration of the shelves inside the plasma chamber. The increase of the treatment time above 40 s did not cause additional surface modifications. Adhesion of the wood-polyethylene composite was noticeably increased when was treated with Ar:O2 LPP. The surface modifications of Ar:O2 LPP treated wood-polyethylene composite were partially lost during 24 h after treatment. [ABSTRACT FROM AUTHOR]

Because of the surfaces of wood-plastic composite (WPC) materials are enriched in polymers of low surface energy, they exhibit low adhesion properties. UV/ozone is proposed as surface treatment for increasing the surface energy and adhesion of WPC materials made with different polymers (polyethylene, polypropylene and polyvinyl chloride). UV lamp-WPC surface distance and time of UV exposure were varied for optimizing UV/ozone treatment of WPC, and UV dose used ranged between 2.02 × 10−14 and 5.05 × 10−12 J·s/m2. UV/ozone treatment created new carbon-oxygen polar groups in WPC surfaces and increased their surface energy, mainly their polar component. Furthermore, ablation of the outermost WPC surface was produced, more noticeably by reducing the distance between WPC surface and UV lamp and by increasing the duration of the treatment. Noticeable increase in 180° peel adhesion was obtained in the joints made with UV/ozone treated WPC at 10–30 mm distance during 1–5 min (i.e., UV dose between 5.61 × 10−14 and 2.53 × 10−12 J·s/m2). Although 180° peel strength of joints made with acrylic adhesive tape and UV/ozone treated WPC for 10 min and 10 mm distance (UV dose: 5.05 × 10−12 J·s/m2) was not increased because of dominant effect of ablation over creation of polar groups, the cross-hatch adhesion to different coatings was highly improved, irrespective of the polymer used and the wood content of WPC; however, the surface modifications and adhesion of UV/ozone treated WPC were more marked when its wood content was higher and by using UV dose between 0.10 × 10−12 and 2.53 × 10−12 J·s/m2. [ABSTRACT FROM AUTHOR]

The cost of most primary materials is increasing, therefore, finding innovative solutions for the re-use of residual waste has become a topic discussed more intensely in recent years. WPCs certainly meet some of these demands. The presented study is focused on an experimental analysis of the effect of surface treatment on the adhesive properties of selected WPCs. Bonding of polymer-based materials is a rather complicated phenomenon and modification of the bonded area in order to improve the adhesive properties is required. Two traditional types of surface treatments and one entirely new approach have been used: mechanical with sandpaper, chemical with 10 wt % NaOH solution and physical modification of the surface by means of a MHSDBD plasma source. For comparison purposes, two high-density polyethylene based products and one polyvinyl-chloride based product with different component ratios were tested. A bonded joint was made using a moisture-curing permanently elastic one-component polyurethane pre-polymer adhesive. Standardized tensile and shear test methods were performed after surface treatment. All tested surface treatments resulted in an improvement of adhesive properties and an increase in bond strength, however, the MHSDBD plasma treatment was proven to be a more suitable surface modification for all selected WPCs.

In this paper, we exclusively studied the effects of dry and wet pulverization of different wood flours on the fatigue performance of polypropylene (PP)/wood flour (WF) composites. Wood flours obtained from cypress and Scots pine trees were pulverized in both dry and wet conditions at two different mill-plate gaps, 200 µm and 350 µm, and were used as reinforcement in PP matrices. Master batches of PP with different types of pulverized WF were compounded before processing in an extruder. The PP/WF composites of initial WF were also prepared for comparison. The prepared composites were analyzed by tensile and fatigue tests. It was found that the tensile properties of wood/polypropylene composites were affected by the pulverization of WF. Fatigue test results displayed that wet pulverization of short cypress flour had a negative effect on the fatigue life of PP/WF composites, while wet pulverization of long cypress flour and pine flour had a positive effect on the fatigue life of PP/WF composites.

This study determined the color change and the physical properties of extruded tea leaf-plastic composite (TPC) after accelerated weathering. The physical properties in TPC were studied using near infrared (NIR) spectroscopy. TPC experienced both change in color and loss of mechanical properties after weathering. The surface characteristics of TPCs also changed significantly after weathering. Exposure of TPC surfaces to weathering resulted in darkening of the color. The average board density (D), modulus of elasticity (MOE) and the modulus of rupture (MOR), for TPCs without weathering, were significantly larger than those for TPCs with different degrees of weathering. The majority of D, MOE and MOR changes occurred during the first 500 hours. The normalised difference vegetation index (NDVI) for TPC without weathering was significantly higher than samples with different durations of weathering. However, there was no significant difference between the values for different exposure times. The NDVI was the most important factor in determining D or MOE. Both the NDVI and the normalised difference lignin index (NDLI) values were used to predict D, using multiple linear regression. The results showed that NIR spectroscopy could potentially be used to determine the properties of tea leaf-plastic composites. [ABSTRACT FROM AUTHOR]

Recycled WPC product using in construction industry occasionally falls short of expectation owing to lack of sufficient ductility and damping capacity, ground waste rubber tire (WTR) with substantial elasticity can be a proper candidate to meet the gap when adding appropriately. Here, WTR after alkali activation was blended in waste wood flour (WWF) treated with compatibilizer, the mixture after oven-dried was subsequently filled into thermoplastic recycled polyethylene (RPE) or polypropylene (RPP) base (WTR/WPC) through hot-press molding process. Mechanical properties (tensile strength ft, flexural strength fb, impact strength fa) of RPE-based and RPP-based WTR/WPC strips with 4 different WTR fractions were characterized. Its damping properties (loss factor η) were measured and identified by ultrasonic agitation and half-power bandwidth identification method, respectively. The coarse WTR has balanced but stable effect on the improvement of ft, fb, fa, and η of WTR/WPC with rigid RPP base than that with flexible RPE, which attributes to the synthetic effects of good deformation capacity of coarse WTR themselves, strong bridging capacity of WWF, and sufficient stick-slip intercalation between WWF or WTR and rigid RPP. The ft, fb and fa, η with 5% coarse WTR of RPP-based WTR/WPC reaches 12.32 MPa, 15.74 MPa; 2.58 MPa and 0.0853, respectively. [ABSTRACT FROM AUTHOR]

We assessed the usefulness of phase-change material (PCM)-based thermal plates fabricated from wood-plastic composites (WPCs) in mitigating the urban heat island effect. The thermal performance of plates containing PCMs with two different melting temperatures and with two different albedo levels was evaluated. The results showed that the PCM with a melting temperature of 44 °C maintained lower surface and inner temperatures than the PCM with a melting temperature of 25 °C. Moreover, a higher surface albedo resulted in a lower surface temperature. However, the thermal performance of PCMs with different melting temperatures but the same surface albedo did not differ. Using PCM-based materials in roof finishing materials can reduce surface temperatures and improve thermal comfort. [ABSTRACT FROM AUTHOR]

In this research work, the possibility of defect detection in wood–plastic composites (WPCs) by shearography method has been assessed. Shearography is one of the practical nondestructive test methods that has been commonly used for detecting defects in polymer-based composites. In this experimental work, first, a defect (hole) was intentionally drilled on one side of the extruded WPC and then the shearography test and analysis was performed on it. This preliminary step was performed to evaluate the application of the test and calibration. Subsequently, the injection-molded WPCs with different volume fraction of wood content were assessed via shearography test for detection of the probable defects in their structures. The results indicated that shearography method can be effectively used for defect revelation in wood–plastic composites. [ABSTRACT FROM AUTHOR]

An experimental study was carried out to investigate the effect of temperature on the mechanical properties and the fracture mechanism of wood–plastic composites (WPCs) under tension. The specimens were prepared via injection molding of various weight fractions of pine wood particles and high-density polyethylene (with and without coupling agent, maleic anhydride-grafted polyethylene (MAPE)). The deformation and fracture behaviors of the samples at different temperatures were studied using a portable microscope setup during the test. The results indicated the significant effect of the test temperature on the fracture mechanism of WPC specimens. At room temperature, the dominant fracture mechanism for the samples without MAPE was debonding, whereas wood cracking was the dominant fracture mechanism in the presence of MAPE. At high temperatures, debonding was prominent over wood cracking in all samples (with and without MAPE), whereas at low temperatures (below 0°C) wood cracking was the dominant fracture mechanism. [ABSTRACT FROM AUTHOR]

Aluminum–wood–plastic composite (A-WPC) beams are a novel type of structural components formed by the co-extrusion of a wood–plastic composite (WPC) on the surface of a hot-rolled aluminum plate. In this study, composite beams of three different spans were designed to examine the flexural performance of A-WPC beams. For each group of specimens, the four-point flexural test was conducted to determine and analyze the failure mode, yield load, flexural bearing capacity, strength utilization, deformability, and strain distribution. The results show that when the span–height ratio is low, folding failure occurs on the compression side of the reinforced A-WPC composite beam, whereas when the span–height ratio is large, deformation and cracks occur on the tension side of the reinforced A-WPC beam first. Compared to the specimen with a span–height ratio of 18, the average ultimate load of the specimen with a span–height ratio of 12 was higher(66.75%), while the average deflection at failure was lower(38.03%). Compared to the specimen with a span–height ratio of 12, the average ultimate load of the specimen with a span–height ratio of 6 was higher(65.97%), while the average deflection at failure was lower(43.86%). The strength utilization of the reinforced A-WPC beam is 8.71%–9.26% higher than that of various engineered wood beams, and 3.46%–8.61% higher than that of various glulam beams. Based on these results, this paper proposed a method for calculating the flexural bearing capacity of the A-WPC beam. The calculation and test results indicate that the reinforced A-WPC beam exhibits excellent flexural performance and can be used as a model for composite beam design. • The reinforcement design of composite beam with aluminum–woodplastic​ composite. • The failure modes and experimental characterization of flexural test of reinforced aluminum–wood–plastic composite beam. • The flexural bearing capacity calculation of reinforced aluminumwood–plastic-composite beam. [ABSTRACT FROM AUTHOR]

Debonding is the dominant fracture mechanism in wood–plastic composites, and the direction of wood fibrils significantly affects the normal and tangential wood–plastic interfacial properties. This study was aimed at simulation of the mixed-mode damage initiation and growth in wood–plastic interfaces using the cohesive zone model. The wood–plastic interfacial properties in longitudinal and transverse directions were determined. The opening and sliding displacements across the wood–plastic interfaces were measured by means of digital image correlation techniques, and the force-displacement diagrams were obtained from the experimental data. The Nelder–Mead algorithm was employed to identify the wood–plastic cohesive parameters through optimization of the force-displacement results of the numerical simulation and experimental data. Accordingly, the obtained cohesive parameters were implemented in the finite element (FE) models for damage prediction of the irregular-shaped particles in wood–plastic specimens. Very good agreements were found between the FE simulations and the observed fracture patterns . [ABSTRACT FROM AUTHOR]

Because the strength of the wood plastic composite (WPC) is based on the fiber-matrix interaction, we have studied the influence of a coupling agent to modify the plastic matrix with different proportions of maleic anhydride-grafted polypropylene (PP-g- MA). Therefore, the physical-mechanical properties of a novel series of WPC with 20% fiber by injection technique were evaluated. It is worth mentioning that in the previous step to the injection process, these materials were mixed in a co-rotating twin screw extruder under mild conditions, because it was possible to reduce by 50% the residence time of the fiber with regard to polymer. The thermogravimetric analysis (TGA) results for the WPC extrudates showed the onset temperatures of degradation with intermediate values T10 of ~ 295 °C compared to the starting components (fiber, PP). The final product had a loss of ~ 3.4% associated with the second thermal process suffered material. The mechanical analysis showed an increase in tensile strength of 20.3% in the new WPC, while the flexural strength reached 46.2%. In the micro-structural analysis of the final products incorporating the fiber into the matrix was made using Scanning Electron Microscopy (SEM). Finally, the optimal mixing ratio necessary to achieve a significant increase in mechanical properties is determined. [ABSTRACT FROM AUTHOR]

This article presents an experimental study on the effect of polymeric matrix flow behavior on the properties of the reprocessed wood–plastic composites (WPC) of high-density polyethylene (HDPE) and wood sawdust. WPCs are considered as sustainable materials due to their durability in the environmental conditions and recyclability. Three grades of HDPE were utilized as polymeric matrix with different melt flow indices (MFIs). Composites containing 60 wt% of sawdust were manufactured via a twin-screw extruder to produce 15 mm rod-shaped profiles (named here as virgin WPCs). In reprocessing, the produced WPC profiles were then ground to obtain WPC granules and then reprocessed (reextruded) via the same extruder. The mechanical properties of both the virgin and the reprocessed profiles were obtained from the bending tests and tensile tests, and the physical tests including water uptake and density measurements were also carried out. Interestingly, reprocessed composites produced with the low and middle MFI HDPE showed an increase in mechanical properties compared with the virgin ones, while for the composites with the high MFI HDPE, opposite result was observed. Water uptake measurement also indicated the best performance of the composites produced with the middle MFI HDPE. [ABSTRACT FROM AUTHOR]

Defibration conditions influence wood fiber characteristics and thereby properties of fiber-based materials. In this study, the effects of several defibration conditions on mechanical and physical properties of fiber-based wood-plastic composites (WPCs) are illustrated. Various WPCs were tested containing different thermo-mechanical pulps (TMPs) or groundwood pulp (GWP), whereby material composition (50 wt% wood fibers, 47 wt% polymer, 3 wt% coupling agent) and the production process (internal mixer, injection molder) were kept consistent. The data from the experiment revealed that differing defibration conditions led to statistically significant differences in the tested flexural, tensile, and impact properties as well as in the water absorption of WPC. Overall, the GWP and the TMP which was produced under the mildest defibration conditions performed best in fiber-based WPCs. Therefore, grinders and refiners may be equally suitable to produce pulp for WPC usage. As a side-effect within this study, the reinforcing effect of fiber application on flexural and tensile properties was on an extraordinarily high level. [ABSTRACT FROM PUBLISHER]

Incineration and landfilling of waste from the timber industry are practices condemned and unused. The reuse of wood waste as a dispersive phase in composite materials has been the focus of much research to develop new products, mainly for the automotive and construction industries. The wood-plastic composites (WPC) present characteristics, such as moderate strength, light weight, and high durability. Besides, they are inexpensive and sustainable, which make them attractive for innovative design. This work investigates the effect of eucalyptus sawdust, a chemical admixture and silica particles on the physical and mechanical properties of WPC upon a statistical methodology. The silica-particle addition was added by the matrix phase replacement to reduce the overall costs, because the latter is nearly 87 % more expensive. A microstructural analysis was conducted to better assess the variables studied. Results have shown that the composites made with 20 wt. % of sawdust addition, 10/50 US-Tyler sawdust particle size and maleic anhydride addition appeared to have acceptable properties for engineering applications. [ABSTRACT FROM AUTHOR]

This paper investigates the fracture mechanism of wood–plastic composites (WPCs) in tension utilizing a direct observation method. Several WPC specimens with various weight fractions (with and without coupling agent) were prepared via injection molding to create complex structures of irregular-shaped wood particles randomly dispersed in a thermoplastic high-density polyethylene matrix. The crack initiation and growth in WPC samples under tension were observed using a portable tensile test setup. It was observed that debonding between the wood particles and matrix was the primary fracture mechanism in WPCs with no compatibilizer. Moreover, the orientation of the wood particle significantly affected the fracture mechanism. On the other hand, the occurrence of wood cracking in the samples made with coupling agents was indicative of the bond strengthening property of these agents. The results indicated that the added compatibilizer affected the fracture mechanism and significantly reduced the ductility. Moreover, the increased amount of wood flour reduced both the ductility and the strength of WPCs. However, it was also observed that the strength reduction can be compensated by adding coupling agent. [ABSTRACT FROM PUBLISHER]

The purpose of this work is to compare the weathering properties of different types of wood-plastic composites (WPCs) based on high-density polyethylene (HDPE), recycled high-density polyethylene (rHDPE-I and rHDPE-II), low-density polyethylene (LDPE), polypropylene (PP), recycled polypropylene (rPP), polystyrene (PS), and recycled polystyrene (rPS). The modulus of rupture (MOR) and modulus of elasticity (MOE) of all WPCs decreased with increasing exposure time of weathering. Of these, the rHDPE-II-based composite exhibited the highest MOR and MOE retention ratios after 2000 h of accelerated ultraviolet (UV) weathering, while the PS-based WPC had the lowest values. In addition, the carbonyl index difference (CID) of various WPCs increased significantly as a function of exposure time. Among them, the PS-based WPCs exhibited the most severe degradation due to photo-oxidation on the surface, while the degradation of PE-based WPCs was the mildest. These results are consistent with the change in the surface cracking and flexural properties of the composites. The PS-based WPCs also exhibited higher moisture diffusion coefficients. The mechanical behavior of WPCs after weathering is influenced by a combination of factors, such as surface oxidation, morphology changes, and moisture absorption. [ABSTRACT FROM AUTHOR]

Abstract: Material performance testing of wood-plastic composites (WPC) requires adequate and time-efficient evaluation of the resistance against fungal colonisation and decay. This study investigates the effects of weathering on WPCs and subsequent material degradation by fungi. Weathering using UV radiation, water spray and repeated frost incidents caused micro- and macro-cracks. Fourier transform infrared spectroscopy (FTIR) demonstrated delignification of wood particles at the weathered WPC surface. Despite of increased surface area, accessibility for fungal hyphae and moisture content, weathering enhanced mass loss due to fungal decay only subtly but not significantly. These potentially enhancing effects for fungal decay are assumed to be outbalanced by delignification due to photo-oxidation and leaching of degradation products resulting in loss of nutrient sources essential for fungal growth. [Copyright &y& Elsevier]

Abstract: Flame retarded wood-plastic composites (WPCs) should allow safe application in areas of fire risk. Halogen-free flame retardants can contain high amounts of nitrogen, phosphorus or sulphur, which may serve as nutrition source for wood degrading fungi and accelerate wood decay. Therefore, the material resistance of WPCs with each of four flame retardants against both fire or fungal decay was examined in comparison to WPC without flame retardant. Expandable graphite showed the best performance against fire in cone calorimetry and radiant panel testing. Two ammonium polyphosphates and a third nitrogen-containing flame retardant were not as effective. Contrary to the possibility that flame retardants might enhance fungal decay of WPC, the opposite effect occurred in case of the wood-degrading fungi Trametes versicolor and Coniophora puteana according to determination of mass loss and decrease of bending modulus of elasticity. Only the surface mould Alternaria alternata slightly increased the degradation of WPCs with nitrogen-containing flame retardants compared to WPC without flame retardant according to mass loss data and FTIR-ATR analyses. Finally, WPC including expandable graphite as flame retardant was effective against both fire and fungal decay. [Copyright &y& Elsevier]

This paper presents a simulation study and experimental verification of a die design in extrusion processing wood-plastic composite profile. Flow balancing at the die exit is a major challenge in the profile extrusion die design as an unbalanced flow causes imperfect profile output. This is especially important when the final profile is complicated by having large dimensions and non-uniform thicknesses. In this study, an I-shaped profile of wood-plastic composite (WPC) has been considered for the die design. Finite element method has been used to design the die channel to yield a balanced output. Phases of die design and manufacture of the I-shape profile is presented. The results show that the prediction by the simulation could give a good insight to the die design which eventually could yield an acceptable profile. [ABSTRACT FROM AUTHOR]

In this study, the adhesion properties of adhesives and paints on wood–plastic composites (WPCs) after plasma treatment at atmospheric pressure and ambient air were investigated. Surface energy determination by means of contact angle measurements according to the Owens–Wendt approach and atomic force microscopy to detect changes in surface topography were carried out. An increase in the polar component of surface energy and an increase in surface roughness after plasma treatment were detected, indicating enhanced bond strength. To confirm these results, bond strength tests were conducted. By tensile bond strength tests, increased adhesion of waterborne, solventborne and oil-based paints on plasma treated surfaces was found. Furthermore, by shear bond strength tests, an increase in bond strength of plasma treated WPCs bonded with poly(vinyl acetate) and polyurethane adhesives was ascertained. [ABSTRACT FROM AUTHOR]

The purpose of this study is to compare the characteristics of wood–plastic composites (WPCs) made of polypropylene (PP) and wood fibers (WFs) from discarded stems, branches, and roots of pomelo trees. The results show that the WPCs made of 30–60 mesh WFs from stems have better physical, flexural, and tensile properties than other WPCs. However, the flexural strengths of all WPCs are not only comparable to those of commercial wood–PP composites but also meet the strength requirements of the Chinese National Standard for exterior WPCs. In addition, the color change of WPCs that contained branch WFs was lower than that of WPCs that contained stem or root WFs during the initial stage of the accelerated weathering test, but the surface color parameters of all WPCs were very similar after 500 h of xenon arc accelerated weathering. Scanning electron microscope (SEM) micrographs showed many cracks on the surfaces of WPCs after accelerated weathering for 500 h, but their flexural modulus of rupture (MOR) and modulus of elasticity (MOE) values did not differ significantly during weathering. Thus, all the discarded parts of pomelo trees can be used to manufacture WPCs, and there were no significant differences in their weathering properties during 500 h of xenon arc accelerated weathering. [ABSTRACT FROM AUTHOR]

The impact of wood waste on the mechanical and biological properties of silicone-based composites was investigated using wood waste from oak, hornbeam, beech, and spruce trees. The density, abrasion resistance, resilience, hardness, and static tensile properties of the obtained WPC (wood–plastic composites) were tested. The results revealed slight changes in the density, increased abrasion resistance, decreased resilience, increased hardness, and decreased strain at break and stress at break compared with untreated silicone. The samples also showed no cytotoxicity to normal human dermal fibroblast, NHDF. The possibility of using prepared composites as materials to create structures on the seabed was also investigated by placing samples in a marine aquarium for one week and then observing sea algae growth. [ABSTRACT FROM AUTHOR]

The impact of wood waste on the mechanical and biological properties of silicone-based composites was investigated using wood waste from oak, hornbeam, beech, and spruce trees. The density, abrasion resistance, resilience, hardness, and static tensile properties of the obtained WPC (wood-plastic composites) were tested. The results revealed slight changes in the density, increased abrasion resistance, decreased resilience, increased hardness, and decreased strain at break and stress at break compared with untreated silicone. The samples also showed no cytotoxicity to normal human dermal fibroblast, NHDF. The possibility of using prepared composites as materials to create structures on the seabed was also investigated by placing samples in a marine aquarium for one week and then observing sea algae growth.

The cost of most primary materials is increasing, therefore, finding innovative solutions for the re-use of residual waste has become a topic discussed more intensely in recent years. WPCs certainly meet some of these demands. The presented study is focused on an experimental analysis of the effect of surface treatment on the adhesive properties of selected WPCs. Bonding of polymer-based materials is a rather complicated phenomenon and modification of the bonded area in order to improve the adhesive properties is required. Two traditional types of surface treatments and one entirely new approach have been used: mechanical with sandpaper, chemical with 10 wt % NaOH solution and physical modification of the surface by means of a MHSDBD plasma source. For comparison purposes, two high-density polyethylene based products and one polyvinyl-chloride based product with different component ratios were tested. A bonded joint was made using a moisture-curing permanently elastic one-component polyurethane pre-polymer adhesive. Standardized tensile and shear test methods were performed after surface treatment. All tested surface treatments resulted in an improvement of adhesive properties and an increase in bond strength, however, the MHSDBD plasma treatment was proven to be a more suitable surface modification for all selected WPCs.