Phase Transition and Mechanical Properties of Elastomer

Mechanical properties of elastomers and their mixtures were investigated with respect to phase transition, that is, strain-induced crystallization of natural rubber. On crystallization of unstretched natural rubber, effect of fatty acids present in the rubber was investigated by polarized light microscopy. The fatty acids were proved to be nucleating agent on the crystallization. The strain-induced crystallization and its effect on the mechanical properties were investigated by measuring tear strength of blend of SBR with natural rubber dispersoid. Despite superposition of tear energy of SBR, the natural rubber/SBR blend showed abrupt increase in tear energy at melting temperature of natural rubber. Since, after removing fatty acids with acetone, the acetone-extracted natural rubber/SBR blend was superposed with temperature shift factor of SBR, fatty acids were suggested to play an important role in not only tear energy but also strain-induced crystallization.