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本文用傅里叶变换红外光谱(FTIR)研究了从高弹态缓冷、高弹态淬火以及其后在低于T_g温度热处理的三种不同热历史聚氯乙烯膜的结构差异。在升温在位FTIR测量中,发现经低于T_g温度热处理的样品在与示差扫描量热(DSC)热焓吸收牛相对应的温度区间有构象突变发生,并用高分子链缠结的观点加以解释。 相似文献
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The polyester-polyetber segmented copolymer has been investigated by rheo-optical FTIR during stretehing for the informastion on strain induced crystallizatinn of soft segment chains, hard and soft chain orientation.At room temperature 15℃, the soft segment chains of polyester-polyether being to crystallize at 220% strain and the degree of crystallixation increa(?)e with draw ratio, but there will not be any soft segment chains crystallization above 21℃even at bigber strain. The average orientation of hard segment chains are higher than that of the soft chain at high strain level, both are positive oriented into the stretching direction at allover strain level. This indicates that the b(?)d (?)ent ch(?)ins are dispersed into the elastomeric phase and without forming spherulite. 相似文献
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高聚物的物理老化和链的凝聚缠结 总被引:12,自引:0,他引:12
本文基于高聚物在物理老化和拉伸变形过程中构象弛豫行为的实验结果,进一步阐明了高分子链局部凝聚缠结的观点。 相似文献
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用红外光谱研究了无规聚甲基丙烯酸甲酯的丙酮、苯、氯仿溶液成膜样品的立构复合状况。结果表明无规聚甲基丙烯酸甲酯在丙酮和苯中确能形成立构复合结构,结构的形成主要是依靠分子链中间规和等规链段的相互作用。对丙酮样品的退火实验表明,在退火过程中能够发生间规链段的自聚集现象。 相似文献
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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. 相似文献
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