Study on the deformation mechanism of metal oxide reinforced wood plastic composites

• Wood plastic composites with 10-30 wt.% wood were studied. • Deformation in compression was dominated by ductile mode and void coalescence. • Zinc, copper and silicon oxide were added to WPC with 10 wt.% wood. • Highest yield stress and strain were achieved for WPC 10 wt.% wood. • Hybrid WPCs with 1wt.% SiO 2 showed highest elastic modulus. Wood plastic composites have attracted attention as alternatives to natural wood and polymer products due to environmental and economic advantages. In this study, wood plastic composites were prepared from high density polyethylene and poplar wood flour (10, 20 & 30 wt.%) and the deformation mechanism was studied. Fourier transform infrared spectroscopy revealed that the bonding between the polyethylene and wood is physical. Compression tests showed that samples containing 10 wt.% wood had the highest elastic modulus of 588.35±128.32 MPa, yield stress of 29.00±5.05 MPa and strain at yield of 4.93±1.73 %. An increase in wood content to 20 and 30 wt.% decreased the elastic modulus, yield stress and strain. Scanning electron micrographs confirmed that the failure was ductile and dominated by void coalescence around wood particles. Furthermore, zinc oxide (0, 1.5, 2, 2.5 and 5 wt.%), copper oxide (0, 1.5, 2, 2.5 and 5 wt.%) and silicon oxide (0, 1, 2 and 5 wt.%) were added in a total constant weight percent of 5 wt.% to wood plastic composites containing 10 wt.% wood. Results showed that the addition of all three oxides decreased the elastic modulus, yield stress and strain except for addition of 1wt.% SiO 2 particles which slightly increased the elastic modulus. These effects were explained by the tendency of silica particles to agglomerate and the tendency of copper and zinc oxides to accumulate around silica nanoparticles. Furthermore, deformation was found to occur by debonding and void coalescence.