分子链大尺度高取向而小尺度接近无规取向态的非晶态聚对苯二甲酸乙二酯膜片

对非晶态聚对苯二甲酸乙二酯膜片经在Ｔｇ以上单轴拉伸然后淬冷至室温的试样，其物理性质的各向同性或各向异性进行了研究．实验结果说明这种分子链大尺度高度取向而小尺度接近无规取向的非晶态（ＧＯＬＲ态）其折光指数和小形变的拉伸模量是接近各向同性的，而热导率和微波介电常数很可能是各向异性的．     

分子链大尺度高度取向小尺度接近无规取向态的无规聚苯乙烯

在Ｔｇ以上３０℃对无规聚苯乙烯（ａ ＰＳ）薄膜进行了热拉伸，然后用各种实验方法测定的结果表明，该试样在红外二向色性，光学双折射及广角Ｘ 光衍射（ＷＡＸＤ）方面表现出各向同性；但是在热膨胀、溶剂溶胀以及应力 应变行为方面表现出显著的各向异性．以上结果表明，该试样小区域基本上无取向，而各向异性的性质是和试样中存在的大区域取向相联系的．     

大区域取向对非晶态聚对苯二甲酸乙二酯结晶的影响

大区域取向对非晶态聚对苯二甲酸乙二酯结晶的影响林辛，吴永升，高金贵，范庆荣（中国科学院化学研究所北京１０００８０）关键词聚对苯二甲酸乙二酯，溶剂诱导结晶，大区域取向Ｓｌｏｎｉｍｓｋｙ等’‘’“最早注意到区分小区域取向和大区域取向的概念，钱人元等”’对...     

FOURIER TRANSFORM INFRARED STUDIES OF POLY (ETHYLENE TEREPHTHALATE) FILM IN THE GLASS TRANSITION REGION

Three specimens from a solution-cast poly (ethylene terephthalate) (PET) film, one being liquid-N_2 quenched from 92℃(Q), one being slowly cooled from 92℃(SC) and one being quenched and sub-T_g annealed at 67℃(AN), have been studied by specimen difference spectra Q-SC and AN-Q and temperature difference spectra T-70 and T_2-T_1 for every 2℃steps on heating to 90℃at 2℃/min. SC and AN showed more gauche conformers than Q. That means that the PET chain has more trans conformers at higher temperatures and some of these are frozen during quenching through T_g. A band at 1340 cm~(-1) has been found to be complex containing overlapping bands reflecting trans in crystalline regions and trans in amorphous regions. The temperature difference spectra on heating through T_g showed that the spectral changes in Q are gradual while a rather abrupt change occurs in AN at 80—82℃for the bands at 1340, 1042 and 1020 cm~(-1). No new conformational structure or new vibrational mode is involved. A kind of locking mechanism is suggested which hinders the molecular vibrational changes in AN below T_g until a sudden release occurs at T_g. These locking sites can be nothing else than sites of tighter local packing of chain segments. Consequently it is believed that inter-chain van der Waals attraction energy plays a dominating role in the volume relaxation and sub-T_g annealing of quenched amorphous polymers.