Glass transition and crystallization phenomena in epoxidized trans-polyisoprene: a differential scanning calorimetry study

The effect of epoxidation of trans-1,4-polyisoprene (TPI) on the glass transition temperature Tg and crystallization of the polymer has been investigated by differential scanning calorimetry. The value of Tg is shown to be linearly dependent on the extent of chain modification, and increases from 201K for the unmodified polymer to 274K for complete epoxidation. The modification inhibits the extent of crystallization, and above 25 mol% epoxidation little or no cold crystallization occurs at 263K. The extent of crystallization is found to fit a previously proposed relationship: log(ΔHm) = logk + nlogxA, where ΔHm is the heat of fusion, k a constant, n the critical sequence length of repeating units for crystallization to occur and xA the mole fraction of unmodified repeat units. For TPI, values of n = 6-7 are found for samples crystallized at 263K.