Performance Of Wood-plastic Composites Research Articles

The Effect of Chopped Glass and Carbon Fiber Reinforcement on Physical, Mechanical, and Fire Performance of Wood Plastic Composites

The Effect of Chopped Glass and Carbon Fiber Reinforcement on Physical, Mechanical, and Fire Performance of Wood Plastic Composites

Experimental investigation on the flexural behavior of aluminum alloy-reinforced wood plastic composite hollow members

An aluminum alloy-reinforced wood plastic composite flexural hollow member was proposed to overcome the low strength utilization efficiency caused by the poor creep performance of wood plastic composite, and the significant reduction of strength and elastic modulus after heating up. The uniaxial tensile experimental test of 6 composite tensile specimens of aluminum alloy-reinforced wood plastic composite and the flexural capacity trial of 4 groups of different spans were carried out in this paper. The results show that the strength and elastic modulus of the composite tensile test pieces can be calculated equivalently according to the stiffness and strength contribution of the wood plastic composite and aluminum alloy. The bearing capacity and flexural stiffness of the bending members decrease with an increasing span. The strain of all specimens agrees with the assumption of the plane section, and no shear lag effect emerges after applying force to the aluminum alloy-reinforced wood plastic composite hollow members. The sections of the samples were transformed into I-sections through stiffness equivalence when calculating the bending bearing capacity of the members. The equivalent parameters were brought into national codes for calculation, and the computed results of the European standard show the best agreement with the experiment results.

Effect of Short Glass Fiber Reinforcement on Physical, Mechanical Properties and Fire Performance of Wood Plastic Composites

Aim of study: This study aimed to improve some physical, mechanical properties, and fire resistance of wood-plastic composites (WPCs) with short glass fiber reinforcement (SGFR). Materials and Methods: The WPCs were reinforced with different ratios of short glass fiber (SGF). The effect of reinforcement on the water absorption (WA), thickness swelling (TS) as physical properties, flexural strength, modulus of elasticity, and tensile strength as mechanical properties were determined. The fire resistance performance was also evaluated by the limit oxygen index (LOI) test. Main results: The reinforcement improved the physical properties. The WA and TS values decreased with increasing glass fiber content. Flexural strength increased up to 28%, while 24% for tensile strength. There was a substantial enhancement in the modulus of elasticity (up to 122%). The glass fiber reinforcement also improved the fire performance of WPCs. Highlights: The higher properties could be obtained by synthetic fiber reinforcement for WPCs.

Enhanced Mechanical Properties of Polyvinyl Chloride-Based Wood-Plastic Composites With Pretreated Corn Stalk.

Wood–plastic composites (WPCs) are a type of environmentally friendly materials widely used in daily life. This paper selected low-value biomass, corn stalk (CS), as the lignocellulosic resource for polyvinyl chloride (PVC)-based WPCs. To depict the relationship between lignocellulosic composition (cellulose, hemicellulose, and lignin) and mechanical performance of WPCs, pretreatments have been optimized to selective removal of lignin using an alkaline-EtOH stewing process and selective removal of hemicellulose using an acid stewing process. The αC sample, in which both lignin and hemicellulose were removed, shows the highest degree of crystallinity (72.60%) as estimated from X-ray diffraction analysis results and fibrous morphology with the highest aspect ratio as seen in scanning electron microscopy images. Compared with PVC/CS, PVC/αC gives a substantial increase in tensile strength and modulus by 37.21 and 21.66% and flexural strength and modulus by 29.98 and 34.88%, respectively. These improvements lie in the reinforcing effect of a fibrous structure and the improved interfacial compatibility as proven by scanning electron microscopy and dynamic mechanical analyzer results. Considering the extracted lignin and hemicellulose can be further developed to valuable biochemicals, the pretreatment to CS adds value to both WPC materials and biorefinery products.

Experimental study on the effect of Cordia africana’s and Austria pine’s wood species on the performance of wood plastic composite

With its market demand expansion and increased application areas, products of wood-plastic composite (WPC) have been developing and growing rapidly in many countries over the last decades. This paper attempts to investigate the effect of wood species that are waste from the furniture industries on the performance of wood-plastic composites (WPCs). The samples were prepared by varying the wood flour species at 30wt% mixed with 70wt% HDPE (High Density polyethylene). The wood species used for samples preparation are Cordia africana’s /wanza/ wood flour, Austria pine’s wood flour, and the mixture of both wood species flour in 15wt% of each wood species and the resulted composites tensile and impact properties determined. Morphological and water absorption characteristics of these composites were also determined. The composite from the mixture of wood species exhibited best interfacial bonding between matrix and reinforcement that resulted in providing the best water absorption property, and the maximum tensile strength of the composite which is, 15.465 MPa. Compared with the pure HDPE, the reduction of impact strength with the addition of wood was also observed. Wood species in wood-plastic composites are an essential factor for the performance of WPCs.

EFFECT OF NATURAL AND ACCELERATED AGING ON THE PROPERTIES OF WOOD-PLASTIC COMPOSITES

The correspondence of natural and laboratory-accelerated aging of WPC has long beenahighly important problem discussed by many scholars. In this work, the changes in moisture content (MC), modulus of rupture (MOR), modulus of elasticity (MOE), screw holding force and creep recovery rates of two groups of wood-plastic composites (WPC) after natural and accelerated aging (high-low temperature cycles and freeze-thaw cycles) were studied to provide guidance for the use of WPC in outdoor applications. The results showed that, after the natural aging and freeze-thaw cycles treatments, MC increased significantly with both 167% of the untreated value of wood-HDPE composites with 30% wood fiber content and a thickness of 25 mm (W25), while 67% and 133% of the wood-HDPE composites with 30% wood fiber content and a thickness of 20 mm (W20), but is almost unchanged after the treatment with high-low temperature cycles. The mechanical strength, including MOR, MOE, screw holding force and creep recovery rate, decreased after natural and accelerated aging. The greatest decreases of MOR, MOE, screw holding force and creep recovery rate were 14%, 13%, 21%, and 7% for W25, while 5%, 8%, 8%, and 14% for W20 respectively. Environmental aging can reduce the strength of WPC, but the bending strength retention rate is more than 85%, showing that performance of WPC is relatively stable compared to wood materials, which is oneof thereasons for the widely use of WPC in outdoor applications.

Weathering performance of waterborne acrylic coating systems on flat‐pressed wood–plastic composites

ABSTRACTThis study applied coating systems containing two different waterborne acrylic resins with an ultraviolet (UV) absorber on the surfaces of polyvinyl chloride‐based flat‐pressed wood–plastic composites (WPCs) evaluated and the effects of waterborne acrylic coating on the performance of WPCs in outdoor conditions. The results showed that waterborne acrylic coating systems enhanced the surface quality of WPC. The decrease in flexural strength was found to reach up to 22%, while it was about 25% for modulus. The color changes on the surface decreased by 55% as a result of the UV absorbability of the coating systems. Moreover, the chemical changes in the composites were found to be almost nonexistent in the attenuated total reflection–Fourier transform infrared spectroscopy for WPCs coated with both formulations. The light microscopy images revealed that the coating systems minimized deformation on the surface. In comparison to the control samples, it was seen that the surface roughness of the WPC was also improved by using waterborne acrylic coating systems. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48518.

Colemanite: A Fire Retardant Candidate for Wood Plastic Composites

The use of raw boron minerals (i.e. tincalconite, colemanite, and ulexite) was evaluated to increase the fire performance of wood plastic composites (WPCs) in comparison with commercially available fire retardants (FRs). Cone calorimetry and limited oxygen index tests were performed to evaluate the fire properties of WPC specimens. Artificial weathering and 3-point bending tests were also performed on the test specimens loaded with the highest loading level of FRs. The most important decrease in the heat release rate values was 42% and 40% in the magnesium hydroxide- and colemanite-added WPCs at a loading level of 15% (w/w), respectively. Incorporation of colemanite and ulexite into the WPCs increased the limited oxygen index levels by nearly 13% at the same loading level. An increase was observed in the peak heat release rate values in all of the WPC specimens after accelerated weathering. All of the FRs had statistically improved MOE values compared with the control WPC specimens. In particular, the incorporation of zinc borate and borax increased the MOE values by approximately 48% and 42%, respectively. Similar to the effect on the MOE values, zinc borate and borax improved the modulus of rupture the most (approximately 18%).

High-Temperature Hot Air/Silane Coupling Modification of Wood Fiber and Its Effect on Properties of Wood Fiber/HDPE Composites

The surfaces of poplar wood fibers were modified using high-temperature hot air (HTHA) treatment and silane coupling agent. The single factor test was then used to investigate the performances (e.g., the change of functional groups, polarity, cellulose crystallinity, and thermal stability) of modified poplar wood fibers (mPWF) through Fourier transform infrared spectrometry, X-ray diffraction and thermo-gravimetric analysis for the subsequent preparation of wood-plastic composites (WPCs). The effect of HTHA treatment conditions—such as temperature, inlet air velocity, and feed rate—on the performances of WPCs was also investigated by scanning electron microscopy and dynamic mechanical analysis. The main findings indicated that HTHA treatment could promote the hydration of mPWF and improve the mechanical properties of WPCs. Treatment temperature strongly affected the mechanical properties and moisture adsorption characteristics of the prepared composites. With the increase of treated temperature and feed rate, the number of hydroxyl groups, holocellulose content, and the pH of mPWF decreased. The degree of crystallinity and thermal stability and the storage modulus of the prepared composites of mPWF increased. However, dimensional stability and water absorption of WPCs significantly reduced. The best mechanical properties enhancement was observed with treatment temperature at 220 °C. This study demonstrated the feasibility for the application of an HTHA treatment in the WPC production industry.

Heat Build-Up and Fire Performance of Wood-Polypropylene Composites Containing Recycled Mineral Wool

The heat build-up and fire performance of wood plastic composites containing recycled mineral wool filler were investigated. Six wood polypropylene composites with recycled mineral wool content between 0 % and 64 % were evaluated. It was found that the heat build-up of the studied composites increased with initial addition of recycled mineral wool, but increasing the content of recycled mineral wool in the composites further did not have a notable effect onthe heat build-up. Fire performance investigation showed that the addition of recycled mineral wool into the composites did not decrease the magnitude of heat release rate peak, but decreased the total heat release of the composites. Investigation of residual masses after the pyrolysis demonstrated a good dispersion of recycled mineral wool fibers in the polymer matrix. It is concluded that fire protection of the polymer matrix is essential when developing the fire performance of wood plastic composites with recycled mineral wool as filler.

Effects of EVA on the Weathering Resistance Performance of Wood Plastic Composite

Wood plastic composite (WPC) in this study was made from high density polyethylene (DHPE) or low density polyethylene (LDPE) with different species wood flour using extrusion. Ethylene vinyl acetate (EVA) was used to improve the weathering resistance performance of WPC. Degradation test and ageing test were employed to study the weathering stability of WPC modified by EVA. The results show that EVA can improve the ageing resistant performance of WPC and have no significant effect on the degradation resistant performance of WPC. It suggests that EVA can be used to improve the weathering resistance performance of WPC.

Effects of different surface treatment for wheat straw on performances of wood-plastic composites

Effects of different surface treatment for wheat straw on performances of wood-plastic composites

Effects of coupling agent treatment on impact strength and thermal expansion performance of wood plastic composite

Effects of coupling agent treatment on impact strength and thermal expansion performance of wood plastic composite

Effects of ethylene vinyl acetate content on physical and mechanical properties of wood-plastic composites

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

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

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

Effect of Fibrillation on the Performance of Wood-Plastic Composites with High Filler Content

Even though fibrous wood filler is known to be effective for improving mechanical and water-resistant properties of wood plastic composite (WPC), it has not been commercially adopted because of its high cost and less handling ability. In the present study, with an expectation of similar positive effect of fibrous wood filler, we carried out a fibrillation of a surface of practical wood flour in pre-mixed compound, containing wood flour, polypropylene, and compatibilizer, for producing WPC with high filler content by means of wet disk-milling. Scanning electron micrography revealed a micro-fibrillation on the surface of wood flour in the ground pre-mixed compound. The size of the surface micro-fiber could be controlled by disk-milling conditions. The formation of the micro-fibrous structure affected the melt viscosity of the compounds and improved mechanical properties of molded samples. The positive effect of the surface micro-fiber formation can be attributed to an interaction among the micro-fibers such as hydrogen bonding and entanglement. The observed reinforcement effect by the surface fibrillation was essentially identical to that of wood fiber although fibrillation was attained just in the surface of wood flour.

Mechanical properties of an extruded wood plastic composite

The focus of this study has been to fully describe the mechanical properties and behaviour of an extruded Wood Plastic Composite product. The use of plasturgy technologies for the elaboration of lignocellulose reinforced composites raises fundamental questions about the behaviour of these materials. Mechanical properties of a composite depend generally on fibre content, fibre/matrix interface link or added coupling agents. Processes play an important role on the reinforcement distribution in the matrix. The main purpose of this paper is to describe mechanical behaviour of WPC composites which are manufactured using an extrusion process. So, complete set of experiments has been realised: tensile, compressive, bending and shear tests. Longitudinal direction refers to extrusion process directional flow and transverse direction specimens have been tested. Mechanical performances of Wood Plastic Composites depend also on the link of fibre/matrix interface, fracture surface has been analysed using an optical microscope.

Morphology of wood species affecting wood-thermoplastic interaction: microstructure and mechanical adhesion

The main objective of the research presented here was to relate anatomical features of wood species that affect the interactions between polymeric phases and performance of wood plastic composites (WPC). These interactions were related to the probable interlocking volume and surface area for stress transfer in a WPC. Composites were produced from different wood species and analyzed using SEM (scanning electron microscopy). Results showed that wood species with high interfacial areas may increase mechanical interlocking, reflected in the viscous constant of the Maxwell model. A complicating factor was that the relation of cell wall thickness-lumen diameter and the interconnectivity between wood cells in a wood, affect the potential for cell collapse. When wood cells collapse, the penetration of the thermoplastic into the wood structure was almost always ceased. The collapse of wood cells during extrusion-injection molding processes reduced the potential surface for stress transfer between phases affecting the mechanical properties of composites. Undamaged wood cells may potentially be filled with HDPE thermoplastic enhancing modulus and increase the strength of WPC.

Dielectric properties of Simon poplar wood flour/polypropylene composite at oven-dry state

Interfacial compatibility is a crucial factor to the performance of wood-plastic composites (WPCs). Yet, so far, the coupling mechanisms of WPC have not been completely understood. In order to further clarify the interfacial coupling mechanism, the dielectric constant and dielectric loss factor of Simon poplar wood flour/polypropylene composites without additives at different wood contents were measured at oven-dry state, and parameters and thermodynamic quantities of the relaxation process were also analyzed and calculated. Consequently, an obvious relaxation process based on the reorientation of methanol groups in amorphous region of wood cell wall was observed exactly that its dielectric loss factor peak decreased with the decreasing wood content within the measured range of 50%–100%. With the trend of dielectric relaxation strength, the two changing trends both revealed that the existence of polypropylene could hinder reorientation of methanol groups. Following the decreasing wood contents, the effect of the hindrance on the dielectric properties turned obvious gradually. It elucidated that introduction of polypropylene caused the quantities of hydrogen bonds formed between each methanol group and the groups around it change. The same conclusion could be drawn from the analysis of thermodynamic quantities during the dielectric relaxation progress.

Correlation of water vapor adsorption behavior of wood with surface thermodynamic properties

To improve the overall performance of wood-plastic composites, appropriate technologies are needed to control moisture sorption and to improve the interaction of wood fiber with selected hydrophobic matrices. The objective of this study was to determine the surface thermodynamic characteristics of a wood fiber and to correlate those characteristics with the fiber's water vapor adsorption behavior. The surface thermodynamic properties, determined by inverse gas chromatography at infinite dilution or near zero surface coverage, were the dispersive component of the surface energy, surface acid-base free energy and enthalpy of desorption of acid-base probes, and surface acid-base acceptor and donor parameters (K A and K D ). Water vapor adsorption was expressed in terms of the percentage of weight gain (ΔW%) resulting from water vapor adsorption on the wood particles, calculated relative to their initial weight after preconditioning in a vacuum dessicator at room temperature. The results showed a strong correlation between ΔW% and K A , and between ΔW% and surface acid-base free energy of water desorption (ΔH AB water ), calculated from experimental K A and K D and values in the literature for acceptor and donor values of water. These results suggest that for substrates such as wood, whose surface Lewis acid-base properties are characterized by a relatively stronger tendency to accept electrons, the key to controlling water vapor adsorption is to manipulate the magnitude of ΔH AB water , primarily via K A , and to a lesser extent via K D .