Abstract
Infrared absorption and dynamic loss tangent (tan δ) measurements were made on poly(ethylene terephthalate) to study the microstructure of the amorphous part which induced Case II swelling. Unoriented films crystallized by various methods including annealing to attain a wide variety of crystallinity were used as samples.
Case II swelling was independent of the amount of regular folding. It was inferred that the microstructure contains a large amount of ethylene glycol residue in trans conformation and is included in well-formed spherulites. The αa absorption in tan δ behavior, which is related to the microbrownian motion of chain segments in amorphous region, indicates that the texture may consist of the chain segments of highly elastic character.
