Characterization on Mixed-crystal Structure of Biodegradable Poly(butylene adipate-co-terephthalate) Copolymer Fibers

摘要

Biodegradable ideal random copolymer poly(butylene adipate-co-terephthalate) (PBAT), with 44 mol% bulylenes terephthalate (BT), was melt-spun into fibers with take-up velocity of 5 km/min. The crystal structure was characterized by WAXD, SAXS and DSC. PBAT fiber has well-developed PBT-like crystal structure despite of its ideal randomness and composition ratio (about 1:1); on the other hand, its melting temperature (ca.121℃) is over 100℃ lower than that of PBT. Based on the quantitative analyses on the lattice spacing, the crystallinity and the fraction of crystallizable BT sequences in PBAT, the crystal structure of PBAT fiber was clarified to be formed by mixed-crystallization of BT and BA units, where BA units were incorporated into BT lattice. This mixed-crystal structure was found to undergo PBT-like reversible crystal from transition upon the application and the removal of stress. However, due to the elastic property of PBAT fibers, its crystal form transition occurred in a higher strain region compared with the α to β transition of PBT fibers.