The possibility of producing wood‐plastic panels using a melt blend/hot press method was studied in this research. The studied panels were compared with conventional medium density fiberboard (MDF) and particleboard (PB) panels. Wood‐plastic panels were made from high density polyethylene (as resin) and MDF waste and PB waste (as natural fiber) at 60, 70, and 80% by weight fiber loadings. Nominal density and dimensions of the panels were 1 g/cm3 and 35 × 35 × 1 cm3, respectively. Mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistances, and impact strength were studied. Results indicated that the mechanical properties of the composites were strongly affected by the proportion of the wood flour and polymer. Maximum values of flexural modulus of wood plastic panels were reached at 70% fiber content. Flexural strength, screw and nail withdrawal resistance, and impact strength of wood plastic composites declined with the increase in fiber content from 60 to 80%. This was attributed to the lack of compatibility between the phases. The produced panels outperformed conventional PB panels regarding their mechanical properties, which were acceptable when compared with MDF panels as well. The best feature in the produced panels was their screw withdrawal resistance, which is extremely important for screw joints in cabinet making. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

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In this research wood-plastic composite (WPC) panels were produced from high density polyethylene, MDF, and particle-board waste at 60, 70, and 80 wt% fiber loadings using the dry blend/hot press method. Physical and mechanical properties of the panels were studied and compared with conventional MDF and particle-board panels. The results indicated that the studied properties of the composites were strongly affected by the kind and proportion of the wood fiber and polymer. Maximum values of the flexural modulus of the WPC panels were reached at 70% fiber content. The flexural strength and impact strength of the WPC panels declined when fiber content increased from 60 to 80%. The flexural modulus of the WPC panels was lower than that of the virgin MDF panels but the flexural modulus of the composites with 70% fibers was close to that of particle-board panels. Flexural strength of MDF panels was noticeably higher than those of wood-plastic composites whereas the flexural modulus of particle-board panels was comparable to that of the wood-plastic composites at 80% fiber content. Furthermore, water uptake of wood-plastic samples increased with the increase in fiber content; however, it was relatively low compared with virgin MDF and particle-board panels.

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In this research, the influence of thermomechanically degraded polypropylene (PP) on mechanical properties of beech sawdust-PP composites was studied. For this purpose, a virgin PP (VPP) was thermomechanically degraded by two times extrusion under controlled conditions in a twin-screw extruder at a rotor speed of 100 rpm and a temperature of 190°C. The results showed that melt flow index, flexural modulus, and hardness of PP were significantly increased by extrusion and re-extrusion of VPP. The PP (virgin and recycled PP in each stage) and beech sawdust were compounded at 60% weight sawdust loading in a counter-rotating twin-screw extruder in the presence or absence of maleated polypropylene (MAPP) to produce sawdust-PP composites. The nominal cross section and density of the manufactured composites were 70 × 10 mm2 and 1 g/cm3, respectively. From the results, the composites containing recycled PP exhibited higher flexural properties and hardness and lower impact strength. In the presence of MAPP, all mechanical properties increased.