Properties of syndiotactic‐rich poly(vinyl alcohol) thin film in water. VII. Elastic behavior of swollen film in water through heating/cooling or cooling/heating cycles

摘要

AbstractThe thermoelastic behavior for highly swollen films of syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) was ascertained under loads in water through heating/cooling or cooling/heating cycles (in the range of 25–70°C). Thes‐PVA films kept at the high temperature of 70°C behaved as a perfect elastomer through the cooling/heating cycle and had very low Young's modulus, 2–3.5 × 106dyn/cm2. When highly swollens‐PVA films were kept at lower temperatures below about 50°C for a long time, microcrystals were formed or propagated in thes‐PVA films and plastic deformation occurred in addition to elastic deformation through heating process. The microcrystalline growth and propagation at lower temperatures were supported by an increase in Young's modulus and a decrease in the molecular weight