Effects of Rice Husk Modification with Liquid Natural Rubber and Exposure to Electron Beam Radiation on the Mechanical Properties of NR/HDPE/Rice Husk Composites

Rice husk (RH) powder is a natural fibre capable of reinforcing natural rubber thermoplastic (TPNR) NR/HDPE composites on specific modification of the particle surface. In this study the modification of RH powder involved pre-treatment with 5% sodium hydroxide (NaOH) solution, soaking in LNR solution and exposure of LNR coated RH to electron beam (EB) irradiation. Preparation of NR/HDPE/RH composites was via melt-mixing in an internal mixer at predetermined conditions. Morphology study of the composites using scanning electron microscope (SEM) showed a homogeneous distribution of modified RH particles and particle-matrix interaction in the composite. Modified RH filled composites exhibited a significant change in mechanical properties. The maximum stress and impact strength were 6.7 MPa and 13.2 kJ/m^2, respectively at 20 kGy radiation, while the tensile modulus was 79 MPa at 30 kGy dose. The interfacial RH-TPNR interaction for the LNR-EB treated RH particles had improved in the EB dosage range of 20-30 kGy. However, over exposure to radiation caused degradation of rubber coat and interaction between particles to increase. Agglomeration of filler particles would occur and caused inhomogeneous distribution of filler in the composite.