Effects of different filler types on decay resistance and thermal, physical, and mechanical properties of recycled high-density polyethylene composites

This research investigated the incorporation of pine dust; a residual material from the furniture industry, into recycled high-density polyethylene (HDPE) to form a wood plastic composite (WPc) and analyzed how this integration affects the structure, mechanical properties, and water absorption of the resulting WPc. Here, after necessary required processing, different samples of different wt% (0wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, and 30wt%) and various sizes (less than 250 μm, 250-500 μm, and 500-1000 μm) of pine dust were mixed into recycled HDPE and fed into a single extrude extruder at 210 0C. The morphologies of the all-prepared samples were taken via stereoscopy microscopy. The tensile test, impact test, and water absorption quality of all WPc samples were tested. The test results showed that the ultimate load and strength were maximum at 15wt%, 20wt%, and 10wt% of 500-1000 μm, 250-500 μm, and less than 250 μm particle size mixed WPc, respectively. The impact test showed the impact resistance was maximum at 15wt% mixed pine dust WPc in all particle sizes. Similarly, water absorption was found to be increased with the increment of wt% of pine dust of all particle sizes in recycled HDPE.

This paper presents the effects of particle size and mixing ratio on the properties including physical, mechanical, and decay resistance of wood plastic composites (WPCs). In addition, it also presents the effects of immersion temperatures on water absorption (WA) and thickness swelling (TS) of the WPCs. WPCs with a thickness of 6 mm were fabricated from Albizia richardiana King & Prain wood particles and recycled polyethylene terephthalate (PET) by the flat-press method. To prepare the WPCs, two different wood particle sizes (0.5–1.0 and 1.01–2.0 mm) were used along with four different mixing ratios (w/w). Subsequently, the physical properties include density, moisture content, WA, and TS, and mechanical properties include modulus of elasticity (MOE) and modulus of rupture (MOR) of the produced WPCs was evaluated. Furthermore, decay resistance was evaluated by the weight loss percentage method. Moreover, the effects of immersion temperatures on WA and TS of WPCs after 24 h of immersion in water at three different temperatures, i.e., 25, 50, and 75 °C were investigated. Results showed that the wood particle size had impact on WPC’s density (only 6% decreased with the increase of particle size); however, the density decreased by 29% when the wood particle content increased from 40 to 70%. The WA and TS gradually increased with the increase of particle content and decrease of particle size. In addition, WA and TS increased proportionately with increasing immersion temperature from 25 to 75 °C. Furthermore, the highest MOE (2570 N/mm2) was found for the WPCs fabricated from large wood particles having the ration of 50:50 (wood particle:PET). For decay resistance, WPCs consisted of larger particles and higher PET content showed greater resistance against decay. Therefore, it is comprehensible that fabrication of the WPCs from 50% large particles and 50% PET is technically feasible and further improvement of WPC performance like enhancement of MOE and reduction of density using coupling agent and agricultural waste fibers, respectively, in the WPC formulation is recommended.

THE RECYCLED plastic and wood waste were recycled to produce new useful product, wood plastic composite (WPC), that having characteristics close to commercial wood. WPC was performed by compounding and forming different recycled polyethylene/wood flour (PE/WF) weight ratios as 70/30, 60/40, 50/50 and 40/60 using twin screw extruder. Based on the mechanical properties measured via dynamic mechanical analysis (DMA), an optimized ratio was found to be (50/50)and was chemically treated with chromic acid solution and investigated by FTIR that approved successful functionalization after treatment. The treated WPC was then coated with different epoxy nanocomposites including reactive rubber nanoparticles (RRNP), montmorillonite nanoclay (MMT) and carbon nanotubes (CNTs). The coated WPC was fully tested using mechanical characterizations (modulus and scratch), water absorption (dist. and sea water), and thermal gravimetric analysis (TGA). The results showed that WPC coated with epoxy/CNT, epoxy/MMT and epoxy/RRNP has an enhanced final product with promising mechanical and physical properties compared to blank or uncoated WPC specimens. Also WPC coated with all epoxy nanocomposites has got enhanced modulus, more scratch resistance, lower water absorption and developed thermal stability, compared to the un-filled epoxy coat. Of those, the epoxy-CNT nanocomposite is an optimized protective coat for WPC even after immersion in water with different conditions.

The objective of this study is to investigate the hygrothermal aging properties of wood plastic composites (WPCs) made of a recycled high density polyethylene (HDPE) highly filled with wood waste, inorganic filler and pigments with a resin/filler ratio of 27/73. Hygrothermal ageing test of the prepared WPCs with three different colors (original, red, and chocolate) was carried out by immersing specimens in distilled water at 45°C for 70 days. The hygrothermal ageing properties including water absorption, moisture diffusion coefficient, surface color change, and flexural properties of the WPCs were investigated. It was found that pigment colored WPCs have better hygrothermal aging properties including lower water absorption, less total color changes, and higher mechanical property retention rate after 70 days hygrothermal aging test. POLYM. ENG. SCI., 55:2127–2132, 2015. © 2015 Society of Plastics Engineers

In this study, Wood Plastic Composites (WPCs) were produced from post-consumer bulky wastes of recycled plastic and wood in order to minimize waste, decrease environmental effects of plastics, reserve natural resources, and support circular economy for sustainable production and consumption. Five different types of polypropylene (PP) or polyethylene (PE) based recycled plastics and wood obtained from urban household bulky wastes were used in the production of recycled WPC composites, r-WPCs. Virgin WPC (v-WPC) and r-WPC compounds were prepared with wood flour (WF) and maleic anhydride grafted compatibilizer (MAPP or MAPE) to evaluate the effect of recycled polymer type and compatibilizer on the mechanical properties. It was found that tensile strength properties of r-WPCs produced from recycled PP (r-PP) were higher than that of the r-WPCs produced from mixed polyolefins and recycled PE. r-WPCs containing anti-oxidants, UV stabilizers, and compatibilizer with different WF compositions were produced from only recycled garden fraction PP (PPFGF) to determine the optimum composition and processing temperature for pilot scale manufacturing of r-WPCs. Based on tensile, impact, flexural, and water sorption properties of r-WPC compounds with different formulations, the optimum conditions of r-WPC compounds for industrial manufacturing process were determined. Surface morphology of fractured surfaces as well as tensile, flexural and density results of r-WPC compounds revealed the enhancement effect of MAPP on interfacial adhesion in r-WPCs. r-WPC products (crates and table/chair legs) based on bulky wastes were produced using an injection molding process at industrial scale by using 30 wt% WF-filled r-WPC compound. This study demonstrated that r-WPC compounds from recycled bulky plastic and wood wastes can be used as a potential raw material in plastic as well as WPC industry, contributing to circular economy.Graphic

Fabricating wood‐plastic composites (WPCs) using recycled plastic and wasted biomass materials is one of the effective approaches to alleviate the global energy crisis and reduce carbon emission. However, the unsatisfactory mechanical properties and fire safety hazards significantly limit the application of WPCs. Herein, recycled high density polyethylene (R‐PE), bean dregs and intumesce flame retardant (IFR) were melt‐blended into flame‐retardant WPC by mechanochemical crosslinking. The results show that the as‐prepared WPC within 22 wt% IFR achieves a satisfactory UL‐94 V‐0 rating and a limiting oxygen index of 31.0%, exhibiting a 40%, 27.6%, and 16.4% reduction in peak heat release rate, total heat release and total smoke production respectively compared to controlled WPC. The results also revealed an unexpected improvement in the mechanical performance of WPCs using the strategy (elevation of 73.6% in the elastic modulus and 75.9% in the breaking elongation, respectively), which can be attributed to the improved interfacial compatibility between R‐PE, bean dregs and IFR. This work offers an innovative and feasible approach for fabrication of high‐performance fire‐retardant WPC based on recycling waste plastics and agriculture wastes, and contributing to the circular economy and sustainability in accordance with the greening strategy in the world.

Three different nondestructive testing (NDT) methods were used on the wood-plastic composites (WPC), which were made of either recycled or virgin high-density polyethylene (HDPE) with poplar fibers as filler. The values of dynamic Young’s modulus of WPC based on recycled or virgin HDPE were measured by the different NDT methods, and the values of static bending modulus of elasticity (MOE) were also determined by three point bending test according to ASTM D790-03. The paper analyzed the variability of the dynamic young’s modulus of WPC based on recycled or virgin HDPE obtained with different NDT methods, and the correlativity was also estimated between the dynamic Young’s modulus and the static MOE of WPC based on recycled HDPE. These results suggest that WPC can be made of recycled HDPE, and the NDT methods can be appropriate to estimate the dynamic Young’s modulus of WPC based on recycled HDPE.

This research work is focused on the development of an alternative method for manufacturing Wood Plastic Composite (WPC) panels based on Wood Veneers (WVs) and High-Density Polyethylene (HDPE) through compression molding, which enhances the physical properties, particularly, water absorption and moisture content. The aim of the present research was to develop alternative panels to replace commercial ones, which are heavily affected by hot, humid climates. In this context, the study began with the design process, which consisted of the collection and processing of primary material, production of the additional components necessary for the manufacturing process, determination of the WV ratio, and preparation of the samples. Thereafter, physical and mechanical tests were carried out on WPC, HDPE (control), commercial gypsum boards (GBs), plywood (PW), and medium density fiberboard (MDF) samples. The results indicate that the method applied to manufacture the WPC samples improved physical properties, achieving a water uptake of less than 4% in both proportions of replacement tested, in contrast to commercial panels, which reached values between 10% and 40%. In addition, a greater load capacity was achieved for lower thick elements.

In this paper, we have investigated the stability, mechanical properties, and the microstructure of wood–plastic composites, which were fabricated using recycled high-density polyethylene (HDPE) with pine wood flour used as fillers. Composite panels were obtained using hot-press molding. The tensile and flexural properties of the composites based on recycled HDPE revealed the strength properties of the composites can be improved by increasing the polymer content, also the composite formulation significantly improved the morphology and the stability. Scanning Electron Microscope (SEM) was used to characterize the morphology of the wood particulate/HDPE interface. It was clearly proved from the results that wood-plastic composite (WPC) based on recycled high density polyethylene (HDPE) can be successfully utilized to fabricate stable and strong WPCs.

Compression wood (CW) is a reaction wood formed in gymnosperms in response to various growth stresses. Many of the anatomical, chemical, physical, and mechanical properties of CW differ distinctly from those of normal wood. Because of different properties, the CW is much less desirable than normal wood. This study was conducted to investigate the suitability of CW flour obtained from black pine (Pinus nigra Arnold) in the manufacture of wood plastic composite (WPC). Polypropylene (PP) and CW flour were compounded into pellets by twin‐screw extrusion, and the test specimens were prepared by injection molding. WPCs were manufactured using various weight percentages of CW flour/PP and maleic anhydride‐grafted PP (MAPP). Water absorption (WA), modulus of rupture (MOR), and modulus of elasticity (MOE) values were measured. The results showed that increasing of the CW percentage in the WPC increased WA, MOR, and MOE values. Using MAPP in the mixture improved water resistance and flexural properties. CW flour of black pine can be used for the manufacturing of WPC as a reinforcing filler. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

<p>Environmental and sustainability concerns push the industries to manufacture alternative materials having less environmental impact. The Wood Plastic Composites (WPCs) produced by blending the biopolymers and natural fillers permit not only to tailor the desired properties of materials but also are the solution to meet the environmental and sustainability requirements. This work presents the elaboration and characterization of the fully green WPCs prepared by blending a biopolymer, BIOPLAST® GS 2189 and spruce sawdust used as filler with different amounts. Since both components are bio-based, the resulting material is entirely environmentally friendly. The mechanical, thermal, structural properties of these WPCs were characterized by different analytical methods like tensile, flexural and impact tests, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD). Their water absorption properties and resistance to the termite and fungal attacks were determined in relation with different wood filler content. The tensile and flexural moduli of WPCs increased with increasing amount of wood fillers into the biopolymer, but WPCs became more brittle compared to the neat polymer. Incorporation of spruce sawdust modified the thermal properties of polymer: The degradation, cold crystallization, and melting temperatures shifted to higher temperatures when spruce sawdust was added into polymer. The termite, fungal and water absorption resistance of WPCs decreased with increasing wood amount in WPCs, but remained in durability class 1 (durable) concerning fungal resistance and quoted 1 (attempted attack) in visual rating regarding to the termites resistance except that the WPC with the highest wood content (30 wt%) rated 2 (slight attack) indicating a long term durability. All the results showed the possibility to elaborate the easy injectable composite materials with adjustable properties by incorporation of BIOPLAST® GS 2189 and spruce sawdust. Therefore, lightweight WPCs allow both to recycle wood industry byproducts and to produce a full ecologic material.</p>

Wood and plastic wastes are endangering our environments in Nigeria today. These waste materials by this study were recycled into Wood Plastic Composites (WPC) by mixing Sawdust (SD) each of Milicia exels, Ceiba petandra and Cola gigantia with polyethylene terephthalate (PET) plastic wastes using weight based ratios 20:80, 30:70 and 40:60 in a locally fabricated extruder. The melted PET and SD mixture were fed into the extruder already preheated to 190°C temperature. The WPC samples were collected into a rectangular mould and compressed to dimension 125mm x 12.7mm x 3.2mm and 25.4mm x 12.7mm x 12.7mm based on ASTM D695 and ASTM D790. Samples were allowed to cool down before subjecting them to physical and mechanical tests. The impact of wood type and mix ratio on the physical and mechanical properties of the WPC (water absorption, thickness swelling, linear expansion, modulus of rupture and elasticity) were investigated using analysis of variance at significant difference (P ≤ 0.05). The SD/PET mix ratio of 20:80 and 40:60 of Milicia exels ranked first in terms of physical and mechanical test respectively. This study shows that there is a future for WPC production in Nigeria for external and internal building applications.

The effect of the untreated and alkaline treated rubberwood flour (RWF) on water absorption, tensile and flexural properties of the wood plastic composites (WPCs) was investigated. The surface of RWF was treated by an alkaline treatment with NaOH solution of 2% w/v concentration for 24 h. The results showed that the RWF treated with alkaline could enhance the interfacial adhesion with rPP and also improve the water absorption and tensile and flexural properties of WPCs. In addition, the alkaline treatment and RWF content significantly affected the tensile and flexural strength. The alkaline treatment also increased water resistance of WPCs, which at 20% RWF content showed the lower water absorption (2.04%). The highest tensile strength (17.75 MPa) and flexural strength (35.73 MPa) of WPCs were achieved with an alkaline treatment at 30 wt% RWF. Moreover, the tensile and flexural modulus of WPCs increased with increasing RWF content (20% to 50%).

In recent decades, due to the increase in environmental awareness and noticeable environmental degradation, the area of wood waste management has attracted increasing attention. The purpose of this study is to develop a new type of highly filled polyurethane wood-composite (PU-WC) by the utilization of large amount of wood wastes without addition of a catalyst. Although wood-plastic composites (WPCs) are widely known, there is still a lack of knowledge about WPCs with a polyurethane matrix. Obtained results showed that composites with a wood content of up to 80% show mechanical properties to commonly used MDF boards. This may be caused proper adhesion between polyurethane matrix and the wooden filler which was confirmed by scanning electron microscopy. The flexural strength of the manufactured composites varied between 19.25 and 25.11 MPa, while the flexural modulus varied between 966 and 1255 MPa. Dynamic mechanical analysis (DMA) of the composites showed a shift of Tgβ (from −70.3 to −52.3 °C) and Tgα (from 94.9 to 117.8 °C) to higher temperatures with increasing filler amount. The observed shift could be interpreted as a reduction of polymer chain mobility and an increase in cross-linking density of composites with a higher amount of wood. This is caused by chemical reactions between isocyanates and reactive hydroxyl groups on the wood surface. Thermogravimetric analysis has shown that PU-WC degrades in one step with Tmax at around 360 °C and T2% significantly reduce with greater addition of wood. Water absorption tests that water absorption strongly depends on wood content and varies between 13 and 80%. Moreover, cyclic water absorption tests showed no considerable difference between the water adsorption of samples after each cycle. Our work suggests that PU-WC can be used successfully as a potential substitute for wood or different types of wood-plastic composites (WPC).

Closed-loop recyclable wood-plastic composite as a sustainable alternative to wood: A solution for utilizing wood waste and promoting carbon sequestration