Atsushi Kaji

Sequence distribution of segmented polyurethane-urea.

Segmented polyurethane-urea (SPU) elastomer was prepared from poly-tetramethyleneglycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI), and ethylenediamine (EDA). The SPU is a kind of block copolymer composed of soft and hard segments. 13C NMR spectra of the SPU were measured and the mean sequence lengths of polyurethane block and polyurea block were estimated from the signals of aromatic carbons. The mean polyurea sequence length was shorter than the hard segment as estimated by X-ray diffraction (Kimura et al.) or by other methods (Suzuki et al.). This polymer was found to be almost a random copolymer. The reactivity of the isocyanate group in MDI decreases slightly when the other side of isocyanate has reacted. The hard segment observed by X-ray diffraction or by other methods might only be the longer fraction of polyurea sequences.

Preparation of an acrylics-grafted polyester and its aqueous dispersion—Structural study of acrylics-grafted polyesters

Structural study of two grafted polyesters, which were different in mechanical properties, was investigated by DMA, TEM, and high-resolution solid-state 13C-NMR. Using DMA and TEM, a separated phase larger than 100 nm was not found in the grafted polyesters. The main chain and the side chain seemed miscible. Analysis of T1ρHs and their distributions made the difference of microstructure in the grafted polyesters clear. P(EA-AA)-grafted polyester, which was very brittle, had a separated phase in the grafted polyester. The separated phase was estimated to be at a size of about 3 nm. On the other hand, P(St-DEF-MAnh)-grafted polyester, which was very ductile, had a homogeneous microstructure. The difference in the microstructures of the grafted polyesters seemed to effect the mechanical properties of the grafted polyesters.

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.