Effects of Wood Particle Sizes on Bonding and Mechanical Strength of Wood Plastic Composites

Abstract

Due to an increasing amount of household plastic waste, sustainable plastics waste management systems have become increasingly important. We report on the feasibility of using recycled polypropylene (PP) from the commonly used plastics to process composite panels for different applications. The plastics were obtained from polymer with Resin Identification Code (RIC) 5, for the PP. The samples were melted and then moulded using an injection molding machine. Other samples were mixed with different wood flour sizes and an investigation carried on the strength of wood-plastic composites (WPCs). The wood flour particle size of 0.268 µm and 1.23 µm were compounded with the plastic at a ratio of 1: 9. Fourier Transform Infra-Red (FTIR) spectra analysis, indicated a decline in the absorption peak of the spectrum for the smallest wood flour particles after the alkali treatment as compared to large particles. The wood flour of particle size of 0.268 µm had the highest ultimate tensile strength values of 15.36 MPa, while wood flour of particle cross-section size of 1.23 µm had the lower ultimate tensile strength values of 10.71 MPa. Analysis showed that as the cross-section size of the wood flour particles within the WPCs decreased, there was a concurrent increase in the ultimate tensile strength of the material. The investigation presents empirical evidence establishing a direct positive relationship between the strength characteristics of wood plastic composite and the particle dimensions of the constituent wood particles. This has been shown to be due to interfacial bonding and effectiveness of load transfer within the composite material.