The glass transition of polymer crystals

摘要: Abstract The statement: “A solid is a condensed phase at temperature below its glass transition”, an operational definition. It leads to the corollary that for crystals be solid, they must their transition. In this paper evidence usefulness of definition presented. based on measurement transition in presence melting and crystallization. experimental tool temperature-modulated differential scanning calorimetry, TMDSC, which enables heat capacity irreversible latent Not only expected change during first-order identified, but it was also discovered some flexible polymer crystal can occur lower than order/disorder process without structure. Typical examples such behavior are seen poly(oxyethylene), poly(oxytetramethylene), aliphatic nylons, most likely polyesters, polyurethanes, polymers with other functional groups, separated by longer CH 2 -sequences. Such transitions above vitrification well-known mesophases described as liquid crystals, plastic condis small large molecules, attesting universality