Synthesis of polyethylene/coir dust hybrid filler via in situ polymerization with zirconocene/MAO catalyst for use in natural rubber biocomposites

In This study, polyethylene/coir dust hybrid filler was synthesized by in situ polymerization using a zirconocene/MAO catalytic system. The obtained hybrid filler was then used for the production of natural rubber biocomposites. The synthesis process of the filler was investigated with variation of coir dust loadings. It was found that increasing the amount of coir dust decreased the catalytic activities due to negative supporting effects. After introducing the PE/coir dust hybrid filler into natural rubber, SEM micrographs showed that the PE/coir dust filler were more compatible with the natural rubber matrix than the pure coir dust. This is owing to the hydrophobicity of the polyethylene in the hybrid filler. The results from a dynamic mechanical analysis showed that the natural rubber biocomposites with the hybrid filler provided a greater storage modulus than that with the pure coir dust. This suggests that the enhanced stiffness of the natural rubber biocomposites is probably due to the strong interaction between the hybrid filler and the natural rubber matrix. The strong interaction in the biocomposite can be confirmed by the low value of a loss factor (tan delta), which indicates a low degree of molecular mobility of the polymer chains, resulted from good adhesion on the filler surfaces.