Plasticization and crystallization of cis‐1,4 polyisoprene mixed with methyl linolate

Crystallization behavior of synthetic cis‐1,4 polyisoprene mixed with methyl linolate was investigated by differential scanning calorimetry and dilatometry. At isothermal crystallization temperature of −25°C, a rate of crystallization decreased with the addition of 1 wt % methyl linolate, whereas it increased with a large amount of methyl linolate, about 30% by weight. Although Avrami constant of cis‐1,4 polyisoprene was 2.82, that of mixtures containing 1 and 30 wt % methyl linolate was found to be approximately 4. This implies the same crystallization mechanism was in operation in the mixtures. Since glass transition temperature, Tg, of cis‐1,4 polyisoprene decreased as the methyl linolate content of mixture increased, methyl linolate was found to be plasticizer for cis‐1,4 polyisoprene. The increase in the rate of crystallization in the mixtures was corresponding to the decrease in Tg.