The effect of reinforcement on the mechanical properties of veneered wood fiber/polypropylene composites assembled with chlorinated polypropylene.

Wood fiber/polypropylene (WF/PP) composites are environmentally friendly materials with high dimensional stability and mechanical properties. However, the applications of WF/PP composites are limited by an unattractive surface texture. In this study, the WF/PP composites were decorated with poplar wood veneer using chlorinated polypropylene (CPP) as a hot melt adhesive, the bonding strength is over 1.18 MPa. Surface bonding strength tests and scanning electron microscopy (SEM) were performed to analyze the quality of the CPP bonding layer. The physical and mechanical properties of the veneered WF/PP boards and unveneered controls were examined to determine the effects of reinforcement. The result shows that after veneered the tension strength and modulus of the whole composite board were increased over 30% and 10%; the flexural strength and modulus were increased over 10% and 20%. Low-velocity impact testing was performed to determine the impact resistance properties of the composites. Higher ratios of wood fiber in the WF/PP composite led to a higher surface bonding strength, which was evident in the SEM images. Wood veneer decoration increased the mechanical strength of the whole composite board. A tighter bond along the CPP layer would provide additional reinforcement of the veneered composite's mechanical properties.