Mechanical Properties Of Wood Plastic Composites Research Articles

Effect of Moisture on the Mechanical Properties of Wood-Plastic Composites Hybridized with Metal Grid Layers.

Wood-plastic composites (WPCs) are some of the most common modern composite materials for interior and exterior design that combine natural waste wood properties and the molding possibility of a thermoplastic polymer binder. The addition of reinforcing elements, binding agents, pigments, and coatings, as well as changes to the microstructure and composition, can all affect the quality of WPCs for particular purposes. To improve the properties, hybrid composite panels of WPCs with 30 wt. % and 40 wt. % of wood content and reinforced with one or three metal grid layers were prepared sequentially by extrusion and hot pressure molding. The results show an average 20% higher moisture absorption for composites with higher wood content. A high impact test (HIT) revealed that the absorbed energy of deformation increased with the number of metal grid layers, regardless of the wood content, around two times for all samples before water immersion and around ten times after water absorption. Also, absorbed energy increases with raised wood content, which is most pronounced in three-metal-grid samples, from 21 J to 26 J (before swelling) and from 15 J to 24 J (after swelling). Flexural tests follow the trends observed by HIT, indicating around 65% higher strength for samples with three metal grid layers vs. samples without a metal grid before water immersion and around 80% higher strength for samples with three metal grid layers vs. samples without a grid after water absorption. The synthesis route, double reinforcing (wood and metal), applied methods of characterization, and optimization according to the obtained results provide a WPC with improved mechanical properties ready for an outdoor purpose.

Mechanical properties of extruded continuous glass fiber reinforced wood Particle/HDPE composites: Effects of glass bundle tex and arrangement

Mechanical properties considerably reduce in wood-plastic composites (WPCs) due to the use of wood particles, so the structural applications of these composites are scarce. Thus, embedding continuous fibers is considered the most reliable method for increasing mechanical properties, although there are still challenges in employing this method on a large scale. In this study, an elaborated, special modular die with the capability of adjusting 14 rovings of continuous fibers was designed, manufactured, and implemented to simultaneously embed continuous glass fibers into the extruded WPC profile. More precisely, it was aimed to investigate the arrangement of fiber rovings into the desired positions in a WPC profile of 70 wt% wood content. Also, the effect of the glass bundle tex (at three level, 1200,2400 and 4800) and the fiber position (at four levels, 0, 2, 4, and 6 mm of relative movement of the guides) on the mechanical properties of WPCs was evaluated. According to the results, the flexural strength of reinforced specimens for 1200, 2400, and 4800 texes increased by 85.8, 107, and 159.7%, respectively, compared with the non-reinforced composite. Theoretical values were calculated and compared with experimental outcomes. Based on the results, The failure mode was non-catastrophic, which means the specimens were able to carry partial loading; a desirable characteristic for the structural applications.

Mechanical properties of wood-plastic composites produced with recycled polyethylene, used Tetra Pak® boxes, and wood flour

The recycling industry has developed rapidly in recent years. Paper, plastic, glass, and metals are the most recycled materials. In this study, composite boards were produced using recycled polyethylene (R-PE) mixed with used Tetra Pak® boxes (TPBs) and pine wood flour (PWF) as fillers. The ratios of TPB to wood flour used in study were 0%, 10%, 20%, 30%, and 40%. Six test groups of composites were prepared. For each group, four composite boards of dimensions 4 × 180 × 220 mm3 were produced. Some of the mechanical properties of the produced boards, such as the flexural strength, flexural modulus, tensile strength, tensile modulus, elongation at break, and Shore D hardness, were determined. The data obtained showed that the flexural modulus, tensile modulus, and density increased with the wood flour content. However, the flexural strength, tensile strength, and elongation at break decreased as the wood flour content was increased. As a result, it can be said that TPBs could be used as a filler instead of wood flour in the production of wood-plastic composites.

Mechanical properties of PVC-based wood–plastic composites effected by temperature

Compared with traditional wooden building materials, polyvinyl chloride (PVC)-based wood–plastic composites have advantages of good weather resistance, easy processing capability, energy conservation, and environmental protection and have been popular and widely used in the field of civil construction and garden engineering in recent years. Due to the difference in the thermal expansion coefficient between its component materials, the stress will accumulate in the wood–plastic composites (WPCs) when the temperature changes, which will affect the mechanical properties of the material and structure. In order to explore the changes in mechanical properties of WPCs under different temperatures and achieve a safe and controllable design, the differential scanning calorimetry (DSC) method was used in this study to measure the glass transition temperature of the WPC between 78.45°C and 88.30°C, and the glass transition temperature (Tg) was about 83.54°C. The tensile, compressive, and bending mechanical property tests of PVC-based wood–plastic composite materials under different temperatures were carried out in the ambient temperature chamber to obtain the failure characteristics, the load–displacement curve, and the influence of temperature on their mechanical properties.

Wood plastic composites (WPCs) from multilayer packaging wastes and rHDPE as pallets for green industry

People are becoming more aware of plastic pollution. Consumers, researchers, and manufacturers are seeking ways to reduce their contribution to the problem. Management of plastic wastes has still been severely environmental problems, especially those with multilayer or multicomponent structures due to the difficulty in recycling process. According to the concept of circular economy, this research aimed to overcome these problems by recycling the multilayer plastic film wastes after use from consumers (classified as post-consumer recycled resin, PCR) and transforming those into high-value products. In this work, Wood Plastic Composites (WPCs) made from mixtures of multilayer packaging wastes (PCRs), recycled high density polyethylene (rHDPE) and wood powders were studied in order to be used as pallets in green industry. Studied factors affecting WPC properties included PCR types (linear low density polyethylene (LLDPE), multilayered oriented polyamide (OPA)/PE and polyethylene terephthalate (PET)/PE films) and rHDPE:PCR weight ratios (40:5, 35:10, 30:15 and 25:20). WPC samples were compounded by a two-roll mill and then shaped into samples by a compression molding machine. Morphological, mechanical and thermal properties of WPCs were examined. From SEM study, it was revealed that wood powders and fibers were well distributed and randomly oriented in WPCs. Both PCRs (OPA/PE and PET/PE) were partially melted because the processing temperatures were below the crystalline melting temperatures of OPA and PET. PCR orientation in WPCs was aligned with the compression direction. Mechanical properties of WPCs from OPA/PE were similar to those of WPCs from PET/PE. WPCs from rHDPE:PCR weight ratios of 40:5 and 35:10 had good mechanical properties which passed the industrial target values. Optimum formulas were then used to form WPC samples by extrusion technique and fabricated into WPC pallets. It was found that the WPC pallets from wastes showed promising properties with high potential to replace conventional pallets in warehouses and industrial transport for green industry.

Mechanical performance of aluminum reinforced wood plastic composites under axial tension: an experimental and numerical investigation

Wood plastic composites (WPCs) are low-cost biomass composite materials with good mechanical stability and good weather resistance that are mainly used in the areas with low stress levels. Aimed at improving the mechanical properties of WPCs, this paper proposes a new WPC reinforced with aluminum. The WPC and aluminum were hot pressed to form an aluminum reinforced wood plastic composites (A-WPC). The axial tensile properties, stress–strain relationship, and failure mechanism of the composite were studied experimentally. The results show that the ultimate stress and strain, elastic modulus, and other mechanical parameters of A-WPCs are much higher than those of WPCs. The elongation at break is 10.13 times that of WPCs, which greatly improves the ductility. Based on the equivalent stiffness theory, two calculation models were proposed to predict the tensile stress–strain relationship of A-WPCs. The tensile rebound process of A-WPCs was analyzed in depth, and then the calculation formula of the residual curvature was deduced to compare with the test results. The experimental results are in good agreement with the calculation results.

Effect of Al powder on mechanical properties and microstructure of wood-plastic composites by selective laser sintering

To solve the problem of the low mechanical properties of wood-plastic composites (WPC) by selective laser sintering (SLS), a tiny amount of Al powders were added into WPC as the reinforcement in this work. Both the mechanical properties and the microstructure of SLS parts were investigated. The results showed that the bending properties of parts first increased to 128.08 % and then decreased to 118.1 % with the increase of Al powder content from 0.1 wt% to 2 wt%. The porosity and sintering neck size of fracture had the same change pattern as the mechanical properties of parts. The strengthening mechanism might be that the good thermal conductivity of Al powder would better facilitate the sintering behavior of composite powder and a stronger interface bonding between wood powders and PES matrix can be obtained. However, the mechanical properties of SLS parts with excessive Al powder decreased due to its reflecting lasers.

Research on the preparation and properties of biodegradable wood-plastic composites

In this work, the PLA/PBS/straw powder wood-plastic composite were fabricated by injection molding process. Special attention was paid to the effects of different parameters of injection molding process on the mechanical properties of the wood-plastic composite. The optimum injection molding process parameters of wood - plastic composites were determined by orthogonal experiment. According to the optimal injection molding process parameters, biodegradable wood-plastic composites filled with different compatibilizers were produced. The effects of MAPLA, silane and combination treatment on the interface compatibility and mechanical properties of the wood-plastic composite were investigated by scanning electron microscope and mechanical properties test. The results showed that the combination of the two compatibilizer treatments can improve the interface compatibility of wood-plastic composites, but the improvement of it mechanical properties is not obvious. The mechanical properties of wood-plastic composites were optimiz when the content of MAPLA was less than 5%.

Preparation and characterization of wood-plastic composite by utilizing a hybrid compatibilizer system

The challenge to improve the interface in wood-plastic composite (WPC) has continued to remain a major setback in the field of wood technology. In this work, a novel hybrid compatibilizer system was developed. Chinese fir (Cunninghamia lanceolata) waste and low-density polyethylene were used as a reinforcing lignocellulosic material and matrix, respectively. Maleic anhydride grafted polyethylene octene elastomer (MPOE), octadecyl organically modified montmorillonite (OMMT) and their combinations were used as compatibilizers. The as-produced composites were characterized for their mechanical and physical properties using the SEM, FTIR, and mechanical testing. The result shows a significant increase in tensile strength of about 41.46 % when a mixture of MPOE and OMMT were used as compatibilizers. Moreover, the addition of MPOE led to the improvement of the impact strength by 26.89 %. Thus, the utilization of both compatibilizers offers an efficient route to improve the interaction and mechanical properties of WPC.

Effect of repeated cycles of wetting and drying on mechanical properties of wood–polypropylene composites

Wood plastic composites (WPCs) are being used for many outdoor applications such as fencing, railing and decking. In outdoor conditions, composites are exposed to varying atmospheric conditions which may influence its mechanical properties. Among the various effects, most predominant one is the moisture absorption due to rainfall. It is necessary to evaluate the effect of moisture absorption/desorption on mechanical properties of WPC. In the present investigation, Melia dubia wood fibre-reinforced polypropylene composites were prepared with and without coupling agent at 40 and 60% fibre loading. Composites were also prepared with three different wood fibre sizes. The composites were exposed to 25 cycles of wetting and drying. During each cycle, the samples were immersed in water for a period of 100 h followed by drying in atmospheric condition for 100 h. Samples were weighed after wetting and drying in each cycle, and mechanical properties were evaluated at 0, 5, 10 and 25 cycles. The results indicated that the composites with higher wood content and fine particle size exhibited higher water absorption and increased loss in mechanical properties. Composites prepared with coupling agent exhibited relative lower moisture absorption and smaller loss in mechanical properties compared to uncoupled composites.

Form-stable phase change material based on fatty acid/wood flour composite and PVC used for thermal energy storage

This work focused on a novel form-stable phase change material (FSPCM) for building energy saving. Capric acid (CA) and palmitic acid (PA) were selected to prepare binary eutectic. The CA-PA/wood flour (WF) composites with different mass ratios were prepared by the vacuum impregnation method. After the shape-stabilized properties were investigated, the results indicated that there were the good encapsulate capacity of WF to CA-PA eutectic and the slight effect of WF on the crystallization. Phase change wood plastic composites (WPCs) using CA-PA /WF composites as the latent heat storage medium and PVC as the matrix were prepared. The relations between mass ratios of CA-PA /WF composites and mechanical properties of WPCs were discussed. The results revealed that the WPCs with appropriate mass fraction of CA-PA eutectic had desired mechanical properties for practical applications. The prepared composites were examined by the scanning electron microscope (SEM), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and accelerated thermal cycling test. SEM images showed that the WPC prepared by the CA-PA /WF composite with the mass ratio of 0.4:1(WPC0.4) was more compact and uniform, but as the amount of CA-PA eutectic increased, more gaps and cracks appeared. DSC results showed that the WPC0.8 melted at 22.03 °C with a latent heat of 28.16 J/g and froze at 20.06 °C with a latent heat of 29.77 J/g, which was more applicable to the thermal energy storage systems for buildings. FTIR results demonstrated that there was no chemical reaction between CA-PA eutectic and components in WPC. The prepared FSPCM exhibited excellent thermal stability for the building materials from the TG analysis. Furthermore, the results of accelerated thermal cycling test showed that the composite had a good thermal reliability after 500 thermal cycles.

Physical and Mechanical Properties of Wood-Plastic Composites Made with Microfibrillar Blends of LDPE, HDPE and PET

The effect of microfibrillar blends of recycled plastics on selected physical and mechanical characteristics of wood-plastic composites (WPCs) was investigated in this study. The production of wood plastic composites was carried out through a two-step extrusion technique. The plastic blends were drawn after extrusion to obtain microfibrillar morphology. The addition of polyethylene-co-glycidyl methacrylate (E-GMA) enhanced compatibility between the two phases and a homogenous structure was seen in the fracture surfaces by scanning electron microscopy (SEM). The crystallinity of base polymers increased with the addition of polyethylene terephthalate (PET) microfibrils, E-GMA and wood flour. The X-ray diffraction (XRD) patterns were also used to determine the crystallinity of all samples. According to the XRD results, the crystallinity degree of recycled plastics was higher than that of virgin plastics. E-GMA improved the water resistance of wood-plastic composites. The mechanical properties of samples were improved with the addition of PET microfibrils. The microfibrillar blending technique was found to be an effective approach for the production of high quality WPCs from recycled plastic blends.

Influence of birch false heartwood on the physical and mechanical properties of wood-plastic composites

The influence of birch false heartwood was investigated relative to the physical and mechanical properties of wood-plastic composites. Birch wood (sapwood and false heartwood) particles were modified with 5 wt% NaOH (by wood content) and 5 wt% 3-aminopropyl-triethoxysilane (by wood content) before being compounded with polypropylene in a co-rotating twin-screw extruder. The compounded composites were then injection moulded into standard test samples. The resulting composites were grouped into four categories: birch sapwood, modified birch sapwood, false heartwood, and modified false heartwood. Neat polypropylene samples were produced as a reference. The samples were tested for their tensile and flexural properties, water absorption, thickness swelling, and ultraviolet aging. The compositions of the composites were analysed using Fourier transform infrared spectroscopy. The results showed that the tensile strength of all of the samples decreased after water absorption. Water absorption decreased the impact strength of all of the composites. Ultraviolet radiation degraded the neat polypropylene and lowered the mechanical properties of all of the composites. Surface chalking was observed in all of the wood-plastic composites exposed to ultraviolet aging, with colours ranging from brown and brownish black to white.

Effects of Premixing Wood Flour with Compatibilizer with Different Characteristics on the Physical and Mechanical Properties of Wood/Plastic Composites

Abstract The addition of maleic anhydride (MA)-modified polypropylene (MAPP) as a compatibilizer increases mechanical and physical properties of wood/plastic composites (WPCs). It is thought that MA graft ratio (Gr), molecular weight (weight-average molecular weight [Mw]), and mixing methods of MAPP affect physical and mechanical properties of WPCs. However, evaluation, especially for mixing order, is not enough. The objective of this study was to investigate the effect of Gr and Mw of MAPP and its mixing methods on the mechanical and physical properties of WPCs. Two types of mixing methods were used: mixing the MAPP with the filler using a Henschel mixer before kneading with PP (premixing method) and mixing all of the materials at one time (one-step mixing method). The WPCs made with the premixing method had lower shear viscosity and higher flexural modulus than those made with the one-step mixing method. The particle size, moisture content, and surface morphology of fillers are thought to be more important in determining the shear viscosity of WPCs than the MAPP itself. The highest tensile, impact, and flexural strengths of WPCs were obtained in the WPC with premixing with low-Gr and high-Mw MAPP. It may be due to the effective reaction of the wood flour with MAPP and higher entanglement between the MAPP and PP. These results suggest that the premixing method could improve productivity and mechanical properties of WPCs.

Dynamic Mechanical Thermal Analysis of Wood Polymer Composite Endurance to Prolonged Ultra Violet Irradiation Exposure

This study was constructed to examine the viscoelastic properties and the microstructure of wood-plastic composites (WPCs) before and after being subjected to UV irradiation. The pellet of the wood polymer composites consists of polypropylene as the matrix and rice-husk flour as the reinforcing filler. The samples were UV irradiated from 5000 hours to 20,000 hours with the increment of 5000 hours to study the effect of weathering on the viscoelastic properties of the WPCs. The microstructures of the surface of the samples were examined using Optical Microscopy (OM). The mechanical properties of WPCs through dynamic mechanical analysis test were assessed for both polyvinyl chloride (PVC) and polypropylene (PP) samples. The value of storage modulus (E’) decreases when been exposed in the ultra violet irradiation, in both glassy and rubbery states. Moreover, the density of the WPC samples is closed to light weight and result is comparable. As for morphological properties test, the surface of cracked, voids appeared at the surface of the WPC samples of both PVC and PP interface and the density of composite decreased.

Heat transfer and mechanical properties of wood-plastic composites filled with flake graphite

Wood plastic composites (WPCs) are a new generation of green composites which can come mostly from recycled materials. The addition of the flake graphite (FG) fillers has a significant influence on the properties of WPCs and this study focuses on the heat transfer and mechanical properties of WPCs. The thermal conductivity increases with the increase of addition amount of FG and decreases with the increase of temperature. By comparing the temperature changes of specimens during heating and cooling process, WPCs with higher FG contents presents higher average equilibrium temperature. The WPCs adding FG fillers obtain a greater flexural modulus but a lower flexural strength due to the heterogeneous distribution of the stress. In general, the mechanical properties of WPCs decrease slightly with increasing content of the FG.

The Effect of MBS Toughening for Mechanical Properties of Wood-Plastic Composites under Environmental Ageing

Wood–plastic composites (WPCs) are a promising environmentally friendly material refers to composite that contain plant powders or fibers as reinforcement and plastic matrix. In this study, an epoxy resin and Methyl metharylate-Butadiene-Styrene Copolymer (MBS) were used as a compatibilizer and toughener and were filled into recycled polyethylene terephthalate (PET) and recycled polyamide 6 (PA6) blends (PET/PA6) and filled with wood flour to prepare the WPCs. The mechanical properties of the WPCs, including the tensile, flexural, and impact properties, with different mixing ratio polymer blends of PET to PA6 (E60/A40, E50/A50, and E40/A60) were investigated under different environmental aging conditions. The experimental results showed that different environmental conditions, such as temperature and humidity, markedly changed the mechanical properties of the WPCs with different mixing ratio polymer blends. In addition, the mechanisms responsible for the interface of the WPCs were identified by studying the fracture surfaces with field emission scanning electron microscopy.

Compósito madeira-plástico a partir de resíduos de três espécies florestais

O presente estudo teve por objetivo avaliar as propriedades físicas e mecânicas de compósitos madeira-plástico, utilizando materiais de baixo nível de processamento. Para tal, utilizou-se madeira proveniente de resíduos de marcenaria, na forma de maravalha, de três espécies florestais (Pinus elliottii, Hovenia dulcis e Maclura tinctoria), e termoplástico do tipo poliestireno. Os dados foram submetidos ao teste de Duncan a 95% de confiabilidade. Para os ensaios mecânicos de módulo de ruptura (MOR) e módulo de elasticidade (MOE) todos os tratamentos apresentaram bons resultados, não se diferenciando entre si. Os ensaios de ligação interna e arrancamento do parafuso não apresentaram resultados satisfatórios, sendo que para este último o melhor resultado foi verificado para Hovenia dulcis. Quanto ao inchamento em 2 h e 24 h, todos os tratamentos mostram resultados positivos. De maneira geral, os resultados não foram influenciados pelas espécies utilizadas.

Physical and Mechanical Properties of Wood Plastic Composites from Teak Wood Sawdust and High Density Polyethylene (HDPE)

Sawdust is a waste from furnitureindustry which is mostly left in the garbage or burn for landfill in hugequantities every year. Efforts to find utilization of this material haveresulted mostly in low value. However, sawdust waste can be considered as analternative to fabricate fiber reinforced polymer composites for furniturefunction. This study was undertaken to determine the physical and mechanicalproperties of wood plastic composites, which were made under laboratoryconditions by hot pressing of high-density polyethylene (HDPE) with teakwoodsawdust as filler. Seven levels of mixed flour, 10, 20, 30, 40, 50, 60 and 70%,based on the composition by weight was added to the HDPE powder with palm oilas coupling agent. A flat pressing technology, the simplest method for capableof large dimension wood plastic panel production, was used to manufacturetesting specimens in dimensions 5.8 x 7.3 cm2. Investigation of themechanical property of the composites material, according to the Americansociety for testing and materials (ASTM) method, was done by impact strengthtester. The measurement results were found that impact strength was decreased uponthe increasing of the sawdust up to 30 % mixing then gradually increased. However,by increasing mixed flour content, water resistance of the panels wasnegatively influenced. The best appearance of composites material in comparisonwith the natural woods was ~30% sawdust powder mixing. The woodplastic panels were utilized for construction of a Thai spirithouse as an outdoor decoration.

Effects of moisture content, wood species, and form of raw materials on fiber morphology and mechanical properties of wood fiber‐HDPE composites

Use of high‐quality wood fibers as reinforcement materials in wood‐plastic composites (WPCs) significantly improves the overall performance of the resulting WPCs. This study focused on the preparation of various types of wood fibers for subsequent use in WPCs. Further, effects of moisture content, wood species, and form of raw material on the quality of prepared wood fibers and on the mechanical properties of wood fiber‐reinforced high‐density polyethylene were comprehensively investigated. The main findings indicated that the overall size of wood fibers increased significantly with the initial moisture content of raw materials; the best morphological features of fibers and the best corresponding mechanical properties of WPCs were obtained for an initial moisture content of 30 wt%. The lengths and diameters of wood fibers prepared from veneers were larger than those of fibers prepared from chips. A wood fiber diameter between 0.21 and 0.29 mm (60–80 mesh) and a length to diameter ratio between 5 and 8 yielded the best mechanical properties for the resultant products. Finally, the composites reinforced with pine fibers exhibited mechanical properties superior to those reinforced with poplar fibers. POLYM. COMPOS., 39:3236–3246, 2018. © 2017 Society of Plastics Engineers