The effects of peroxide treatment on composites of linear low density polyethylene and short sisal fibre
Mokoena, Moipone Alice
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In this work sisal fibre (Agave sisalana) was used as reinforcement in LLDPE-sisal fibre reinforced composites. In recent years there has been an increasing interest in finding new applications for sisal fibre as reinforcement in composites. The inherent problem that sisal fibre is hydrophilic in nature and thus absorbs a considerable amount of water, poses a thread towards achieving good interfacial adhesion with hydrophobic thermoplastic materials. Thus it was necessary to consider treatment of the composites. Dicumyl peroxide (DCP) was used for this purpose. The influence of sisal fibre and DCP content on the thermal, mechanical and visco-elastic properties of LLD PE-sisal fibre composites was investigated. Results show a significant decrease in water absorption for the DCP treated samples, changes in the polymer melting behaviour as a result of the presence of sisal as well as cross-linking/grafting in the presence of DCP, and significantly improved stress and strain at break, especially at low sisal contents. The presence of sisal increases the tensile modulus, but DCP treatment does not seem to have much influence on this property. Stress relaxation reduces with increasing sisal content, but again DCP treatment does not seem to have much influence. Although not proved beyond any doubt, there are indications that peroxide treatment, especially at high DCP content, causes grafting between LLDPE and sisal, as well as degradation of LLDPE.