Investigation of Crude Palm Oil as an Alternative Processing Oils in Natural Rubber : Effect of the Unsaturated Fatty Acid

Abstract

Petroleum based processing oils is the hydrocarbon oils derived from petroleum refining process and commonly used as extender or processing oils to improve the rubber processability. Hydrocarbon oils can be classified as paraffins, aromatics, naphthene and olefins oil based on their molecular structure. The studies on replacement of hydrocarbon oils with natural processing oils had been studied by vast number of researchers due to finite resources and the toxicity of the hydrocarbon oils which enhanced awareness in using natural based oils. These natural processing oils are from vegetable or animal. The vegetable oils contain mainly unsaturated fatty acids. Studies showed that the unsaturated fatty acids affect the cure characteristics and the mechanical properties of the filled vulcanizates as these fatty acids took part during the vulcanization and promote the filler-rubber interaction. In this study, natural rubber (NR) of grade Standard Malaysian Rubber 20 (SMR 20) with the loadings of paraffin oil (PO) and crude palm oil (CPO) between 1 to 5 phr was investigated. Within the loadings of PO and CPO studied, the unsaturated fatty acid in CPOs were reported to results in plasticizing effect which results in lower minimum and maximum torques. Though that the unsaturated fatty acid which took part during the vulcanization prolonged the cure time, it resulted in higher CB-SMR 20 interaction. The tensile properties, tear strength, hardness and abrasion resistance of the CPO recipes were affected by combination of plasticizing effect and better CB-SMR 20 interaction.