Hironobu Kitagawa

The Influence of Feed Ratio of Starting Material on the Character of Polyester-Polyester Block Copolymer

The polyester-polyester block copolymers were prepared by the reaction of poly (1, 4-butylene terephtalate) (PBT) with e-caprolactone (e-CL). The effects of molar ratio of PBT to e-CL on molecular weight and on the character of block copolymer were studied. At the higher molar ratio of hard segment, the reduced viscosity ηsp/c of block copolymer tended to be higher. Good correlation between the numberaverage molecular weight _??_n and the intrinsic viscosity was well confirmed. The sequence lengths of the hard and soft segments depended both on the feed ratio of hard-PBT and soft-e-CL, and on the rate of transesterification. Average sequence length of hard segments (m) became shorter with increasing the amount of e-CL in feed, whereas that of soft segments (n) became longer. DCS curves of the copolymer having soft segment content lower than 60wt% showed no soft crystal melting. However, melting could be observed when soft segment contents of copolymers were higher than 75wt%. The hardness and modulus of block copolymer decreased with increasing the weight ratio of soft segment up to 60wt%, while they became higher when soft segment content was over 75wt%.

Studies on Polyester Elastomer I. Polymerization Behavior of .EPSILON.-Caprolactone for the Formation of Polyester-Polyester Block Polymer.

ポリ (1, 4-ブチレンテレフタレート) (以下PBTと略す) にe-カプロラクトン (以下e-CLと略す) を開環付加重合する挙動について調べ, 以下の知見を得た. PBTとe-CLの付加反応はPBT末端カルポキンル基を開始剤として進み, 反応速度はイオン成長反応速度式に従い, 平衡モノマー濃度よりこの反応は著しく正反応サイドへ進み, 反応温度235℃では反応時間120～150分でほぼ平衡に達する. 付加反応中に生じるエステル交換反応についてDSC法で調べたが, 反応時間90～120分で融点が安定し, 反応開始後短時間でブロック性が決定される. 13C NMRで反応中のハード及びソフトセグメント長の変化を見ると, DSC法の結果と一致しており, PBTとe-CLの仕込比率が7対3, 反応温度235℃の条件下では反応開始後90分でブロック性が決定される. 以上のことよりPBTとe-CLを反応することにより高融点のポリエステル-ポリエステルブロックポリマーが得られことが分かった.