Effects of organic peroxide and polymer chain structure on morphology and thermal properties of sisal fibre reinforced polyethylene composites

The effect of polymer chain structure, addition of dicumyl peroxide (DCP) to initiate grafting onto the fibre, and different fibre loadings on the morphology and thermal properties of polyethylene/sisal fibre composites was investigated. The gel content results suggest both crosslinking between the polyethylene chains and grafting onto the sisal fibres. There were significant differences in gel contents between the composites because of the differences in the polyethylene molecular structures. The SEM micrographs of the samples show clear evidence of grafting, particularly in the case of the LDPE and LLDPE composites. The presence of the sisal fibres gave rise to thermally less stable composites compared to the neat matrices, whereas marginal differences in stability were observed between the untreated and peroxide treated composites. The DSC results show interesting trends in terms of the influence of fibre content and dicumyl peroxide treatment on the crystallisation behaviour of the composites.