The effects of expoxidized soybean oil on the mechanical, water absorption thermal stability and melting processing properties of wood plastic composites
To promote the environmentally friendly properties of wood plastic composites (WPC) fabricated via a polyvinyl chloride resin matrix, the effects of different amounts (0, 5, 15, 25, and 35 phr) of expoxidized soybean oil (ESO) on mechanical strengths, thermal stability, melting processing properties, and water absorption of the composite samples were studied. The results show that the tensile strength of WPC decreased. However, the elongation at break, water absorption and thickness swelling rates increased, especially for ESO addition amounts beyond 15 phr. The flexural strength and modulus of WPC followed an upward trend initially (at 5 phr ESO), then switching to a downward trend. The initial thermal stability at the first thermal decomposition stage and the melting processing temperature of the composites ewere effectively improved with the increase of ESO level. Compared to the samples without added ESO, the maximum thermal decomposition temperature (Tmax1 and Tmax2) values of the composites increased by 31°C and 8°C, respectively, while the melting processing temperature of the composites significantly decreased by 24°C corresponding to an added level of 35 phr. In summary, the WPC samples with 5-15 phr ESO addition not only effectively retained their the mechanical strengths and water absorption stability, but also improved their the thermal stability and melting processing properties.