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 (Tg) and β transition (Tβ) regions. PVC, when quenched through Tg and then annealed at 40°C, exhibits a sub‐Tg 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‐Tg endothermic peaks previously observed by differential scanning calorimetry (DSC). A sub‐Tβ peak in the tan δ or the loss modulus functions can be produced by quenching through Tβ. The effect of heating rate on the sub‐Tβ peak is explored.