Non-isothermal thermogravimetric analysis (TGA) was employed to investigate the degradation of polypropylene (PP) during simulated product manufacturing in a secondary process and wood–plastic ...composites. Multiple batch mixing cycles were carried out to mimic the actual recycling. Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW), Friedman, Kissinger and Augis models were employed to calculate the apparent activation energy (Ea). Experimental investigation using TGA indicated that the thermograms of PP recyclates shifted to lower temperatures, revealing the presence of an accelerated degradation process induced by the formation of radicals during chain scission. Reprocessing for five cycles led to roughly a 35% reduction in ultimate mixing torque, and a more than 400% increase in the melt flow rate of PP. Ea increased with the extent of degradation (α), and the dependency intensified with the reprocessing cycles. In biocomposites, despite the detectable degradation steps of wood and PP in thermal degradation, a partial coincidence of degradation was observed under air. Deconvolution was employed to separate the overlapped cellulose and PP peaks. Under nitrogen, OFW estimations for the deconvoluted PP exposed an upward shift of Ea at the whole range of α due to the high thermal absorbance of the wood chars. Under air, the Ea of deconvoluted PP showed an irregular rise in the initial steps, which could be related to the high volume of evolved volatiles from the wood reducing the oxygen diffusion.
In this study, the influence of fire retardants, namely aluminum trihydrate, zinc borate, melamine, graphite, titanium dioxide on the durability of polypropylene-based co-extruded wood–plastic ...composites is studied. The composites underwent accelerated weathering under a xenon-arc lamp source during 1000h. FTIR analysis of the composite surface revealed a degradation process which was accompanied by chemical changes, including vinyl-like and carbonyl groups accumulation; fire retardants did not influence the photo-oxidation mechanism of the composite. Fire retardant-loaded samples had smaller color change compared to the unfilled one. The tensile properties of all composites declined after the weathering. Significant changes in the surface morphology of the weathered composites were observed with a scan electron microscope.
•Cascading use potentials of resources in Wood–Plastic Composites are addressed.•Using recycled HDPE is technically and economically feasible up to 70% in the matrix.•Economic feasibility of using ...recycled wood depends on waste wood processing and sorting techniques.•Technical properties of WPC are more affected by wood proportion than wood origin.
The market share of Wood–Plastic Composites (WPC) is small but expected to grow sharply in Europe. This raises some concerns about suitable wood particles needed in the wood-based panels industry in Europe. Concerns are stimulated by the competition between the promotion of wooden products through the European Bioeconomy Strategy and wood as an energy carrier through the Renewable Energy Directive. Cascade use of resources and valorisation of waste are potential strategies to overcome resource scarcity. Under experimental design conditions, WPC made from post-consumer recycled wood and plastic (HDPE) were compared to WPC made from virgin resources. Wood content in the polymer matrix was raised in two steps from 0% to 30% and 60%. Mechanical and physical properties and colour differences were characterized. The feasibility of using cascaded resources for WPC is discussed. Results indicate the technical and economic feasibility of using recycled HDPE from packaging waste for WPC. Based on technical properties, 30% recycled wood content for WPC is feasible, but economic and political barriers of efficient cascading of biomass need to be overcome.
•AFM was firstly used to characterize the surface morphology and roughness of weathered wood–plastic composites.•Composites containing lignin showed less loss of flexural strength and modulus and ...less roughness on weathered surface compared with lignin-free composites.•ATR-FTIR and XPS analyses demonstrated in detail that significant chemistry changes occurred in wood flour, lignin, and cellulose.•The crystallinity of PP increased in all weathered samples due to chain scissions and recrystallization.•The stabilization and antioxidation effects of lignin were proved.
In this study, six groups of polypropylene composites reinforced with wood flour (WF), cellulose, and lignin at different loading levels were exposed in a QUV accelerated weathering tester for a total duration of 960h. The changes in surface morphology, chemistry, and thermal properties of weathered samples were characterized by atomic force microscope (AFM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetric (DSC), respectively. The flexural properties of all samples were tested after different durations of weathering. The results showed that: (1) the surface roughness of all samples increased after weathering; (2) composites containing lignin showed less loss of flexural strength and modulus and less roughness on weathered surface compared with lignin-free composites, indicating the functions of stabilization and antioxidation of lignin; (3) the crystallinity of PP increased in all weathered samples due to chain scissions and recrystallization; (4) ATR-FTIR and XPS analyses demonstrated in detail that significant changes occurred in surface chemistry, accompanied by the photodegradation and photo-oxidation of lignin and cellulose with prolonged weathering time.
•Fabricated photothermal and storage conversion bio-composites with unique honeycomb structure on phase change microcapsules.•Reinforce the energy storage, temperature regulation ability, interface ...strength and photothermal conversion efficiency of WPC.•Thermal transfer and storage mechanism of the composites are inspected thoroughly.
A novel thermal energy storage (TES) composites system consisting of the microPCMs based on n-octadecane nucleus and SiO2/honeycomb-structure BN layer-by-layer shell as energy storage materials, and wood powder/Poly (butyleneadipate-co-terephthalate) (PBAT) as the matrix, was created with the goal of improving the heat transmission and photothermal responsiveness of building materials. The microPCMs were made via mini-emulsion interfacial polycondensation and electrostatic self-assembly to anchor BN on the surface of the SiO2 shell. The two kinds of microPCMs we designed had regular spherical morphology, BN was successfully anchored outside the SiO2 shell, showing a honeycomb structure and good heat storage performance (140.4 J/g and 140.6 J/g). The thermal energy storage wood plastic composites (TES WPCs) had considerable energy storage capacity and temperature regulation ability. The TES WPCs with the unique honeycomb structure of BN-MicroPCMs (BN-WPC) had better heat transfer performance and photothermal conversion efficiency (69.54%), and the thermal conductivity, specific heat capacity and energy storage efficiency of which were increased by 75.06%, 87.06% and 200% respectively. Meanwhile, the unique honeycomb structure strengthened the interfacial bond strength of TES WPCs and brought satisfactory mechanical strength, and the tensile strength, elongation at break, bending strength and bending modulus of BN-WPC are increased by 51.16%, 97.01%, 81.28% and 742.74%, respectively compared with the WPC added with S-MicroPCMs (S-WPC). These results indicated that this research by designing the BN honeycomb structure layer on the traditional microPCMs surface, obtained the rapid thermal response of high-performance TES WPCs in residential construction, thermal energy storage, solar energy collection system and thermal regulation has broad application prospects.
Lightweight wood‐plastic composites (WPC) are made from expandable polystyrene and wood particle using a mold foaming technique, and their fire resistance is improved with the addition of melamine ...phosphate (MPP) and aluminum hypophosphite (AHP). Flame retardancy is characterized and shown to be significantly enhanced on limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimetry tests. The fire behavior investigation indicates that the LOI value of WPC/12MPP/3AHP sample can reach 33.5% and UL‐94 rating was V‐0. The total heat release, total smoke production, peak of smoke production rate and peak of heat release rate of WPC/15MPP are reduced by 23.2%, 47.5%, 28.6% and 17.3%, respectively, compare with the pure one. Mechanical properties characterization of composites also reveals that MPP/AHP has a positive influence on the impact strength, modulus of elasticity and modulus of rupture.
The preparation process of lightweight wood‐plastic composites.
Wood–plastic composites were injection-molded from recycled acrylonitrile–butadiene–styrene and polystyrene from post-consumer electronics in the interest of resource efficiency and ecological ...product design. The wood content was raised in two steps from 0% to 30% and 60%. Reinforcement performance of recycled particleboard was compared to virgin Norway spruce. Styrene maleic anhydride copolymer was used as the coupling agent in the composites with a 60% wood proportion to investigate the influence on interfacial adhesion. The composites were characterized by using physical and mechanical standard testing methods. Results showed increased stiffness (flexural and tensile modulus of elasticity), water uptake and density with the incorporation of wood particles to the plastic matrices. Interestingly, strength (flexural and tensile) increased as well. Wood particles from Norway spruce exhibited reinforcement in terms of strength and stiffness. The same results were achieved with particleboard particles in terms of stiffness, but the strength of the composites was negatively affected. The coupling agent affected the strength properties beneficially, which was not observed for the stiffness of the composites. The presence of cadmium, chromium, copper, arsenic and lead in the recycled resources was found by an elementary analysis. This can be linked to color pigments in recycled plastics and insufficient separation processes of recycled wood particles for particleboard production.
•Recycled WEEE-plastics and particleboard were investigated for potential use in WPC.•Increasing wood content resulted in increased stiffness and strength of WPC.•The coupling agent SMA affected strength properties but not the stiffness of WPC.•Elementary analysis obtained content of Cd, Cr, Cu, As and Pb in recycled resources.
The Babool, Sheesham, Mango, and Mahogany trees are commonly found in India. The wood-plastic composites (WPCs) were prepared by injection molding using wood dust of the selected Indian trees as the ...reinforcements in the polypropylene matrix. The mechanical, wear, and morphological characterizations of WPCs were performed. Different wood dust proportions were utilized to observe the comparative variation in Young's modulus, wear rate, and morphology of the WPCs. The resistance to natural weathering and biodegradability of WPCs were evaluated following ASTM D1435–99 and ASTM D5338-11 respectively. The degradation of the WPCs due to Ultraviolet-B (UVB) radiation is also examined. The structure-property relation was established and the usability of different WPCs for different applications was highlighted.
In this study, polypropylene (PP) was reprocessed at various cycles to simulate recycling to be used as a matrix for highly loaded wood plastic composites (WPC). The neat and composite samples were ...produced using a batch mixer and injection molder. The extent of PP recycling was analyzed using chromatography, rheology, microscopy, and other physical/mechanical properties. While successive thermo-mechanical processing caused considerable chain scission of the PP, shown by the reduction in melt viscosity and the average molecular weight. While, other properties like tensile strength and modulus did not change significantly. The repeated reprocessing allowed for the incorporate of high 70 wt% wood flour (WF) to produce highly filled WPC. Overall, the WPCs displayed appealing physical properties through the increase in hardness and stiff characteristics while reducing the composites elongation by ~17%. This indicates that the recycling of PP could be of great importance to reduce waste accumulation by producing WPCs for construction and other applications.
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