Dynamic mechanical studies of thermal aging in poly(vinyl chloride)

The effects of thermal aging on the dynamic mechanical properties of rigid poly(vinyl chloride) (PVC) and chlorinated poly(vinyl chloride) (CPVC) are examined in the glass transition (T_g) and β transition (T_β) regions. PVC, when quenched through T_g and then annealed at 40°C, exhibits a sub-T_g peak in the loss modulus function. The position of the peak moves to higher temperatures with increasing annealing time. The effect is analogous to sub-T_g endothermic peaks previously observed by differential scanning calorimetry (DSC). A sub-T_β peak in the tan δ or the loss modulus functions can be produced by quenching through T_β. The effect of heating rate on the sub-T_β peak is explored.