Mechanical and Chemical Resistance Properties of High Density Polyethylene Filled with Corncob and Coconut Fiber

The effects of incorporating coconut fibre and corncob fibre as fillers on the properties of high density polyethylene (HDPE) have been studied. The study also investigated the effects on tensile strength and hardness of the composites after immersion in different chemical media, and the long-term water uptake behavior of the composites were also investigated. Results showed that the incorporation of coconut, and corncob fibres into HDPE increased the tensile strength of HDPE. While coconut fibre increased the hardness of HDPE at all the fibre contents investigated, the hardness of all corncob fibre filled HDPE was lower than the unfilled HDPE. The specific gravity of HDPE composites was found to increase with increase in fibre content and at the fibre contents considered. The tensile strength and hardness of coconut, and corncob fibre filled HDPE were greatly reduced after immersion in 10% HCl, 13% bleach, and 10% NaOH. The 3% H2O2 and 1% soap solution had negligible effects and showed small reduction in composite properties. All the prepared composites absorbed more water than unfilled HDPE. The amount of water absorbed was found to depend on fibre type, fibre content, and immersion time. None of the prepared composites reached equilibrium water absorption after seven weeks immersion in water. The present study highlighted the benefits and limitations of coconut, and corncob fibres as fillers for HDPE for barrier applications. It is hoped that these fibres should be considered by the plastic/composite industries for their various applications.