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1.
The high-temperature crystallization of poly(p-phenylene terephthalamide) (PPTA) from dilute organic solutions was achieved through the introduction of a non-solvent, or precipitating agent, at the desired crystallization temperature. The morphology and crystal structure were examined for crystals produced from PPTA polymer with two different molecular weights (Mw = 46000 and 3430 g mol−1), using transmission electron microscopy. For the high-molecular-weight polymer, ribbon-like crystals were produced, while the low-molecular-weight polymer yielded small needles or platelets. In both cases, electron diffraction showed that the Northolt allomorph was obtained. For the high-molecular-weight polymer, the molecular axes were parallel to the ribbon axes in a chain-extended type structure. A hypothesis for the orientation of the low-molecular-weight PPTA in the small platelets, is also given. 相似文献
2.
Ying‐Hung So 《Polymer International》2006,55(2):127-138
Poly(2,4‐dimethyl‐1,4‐phenylene oxide) (PPO), poly(benzo[1,2‐d:5,4‐d′]bisoxazole‐2,6‐diyl‐1,4‐phenylene) (PBO) and poly(benzo[1,2‐d:4,5‐d′]bisthiazole‐2,6‐diyl‐1,4‐phenylene) (PBZT), which are polymers with extended conjugated structures, undergo a self‐sensitized photo‐induced electron‐transfer reaction. A second component is not required. This article presents many similar observations on these polymers when they are exposed to light and evidence to support the proposed photo‐induced electron‐transfer mechanism. Methods to stabilize these polymers against photo‐oxidation are also described. Workers investigating other conjugated polymeric systems may find the experimental methods, observations and polymer stabilization approaches discussed in this review useful. Copyright © 2005 Society of Chemical Industry 相似文献
3.
Graft copolymerization of acrylic acid (AA) onto polyphenylene sulfide (PPS) nonwoven initiated by low temperature plasma was studied. The effects of various conditions on graft reaction and the grafting rate were investigated. SEM images showed that PPS nonwoven was grafted, and the graft copolymerization only occurred on the surface of PPS. It may be due to the chain transference going with the graft copolymerization. It was found that with the increasing of plasma power, treatment time, space between electrodes, monomer concentration, and temperature of graft polymerization, the grafting rate increased at first, went to the top, and then decreased. The PPS nonwoven surface graft reaction could be optimized by the following processing conditions: 120 s of plasma treatment time, 50 W of plasma power, 1.5 cm of space between electrodes, 30% (w/w) of monomer concentration, and 50°C of temperature of graft polymerization. Measurement of XPS showed that the peak of C1s of graft polyacrylic acid was existed, and the peak area increased with the increase of the grafting rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5884–5889, 2006 相似文献
4.
PPTA/尼龙1010分子复合材料流变行为的研究 总被引:2,自引:0,他引:2
本文采用共沉淀法制备了聚对苯二甲酰对苯二胺(PPTA)/尼龙1010分子复合材料。测定了PPTA/尼龙1010分子复合材料的流变行为,发现PPTA使尼龙1010的表观熔体粘度变大,且PPTA/尼龙1010分子复合材料的表观熔体粘度对温度的敏感性不象尼龙1010那样突出。 相似文献
5.
低烟阻燃高抗冲聚苯乙烯的研究 总被引:17,自引:0,他引:17
用氢氧化镁(MH)和硼酸锌(ZB)与十溴二苯醚(DBDPO)-氧化锑或包覆红磷共同使用以阻燃高抗冲聚苯乙烯(HIPS)可使燃烧过程中的发烟量降低40%左右。与十溴二苯醚-氧化锑和包覆红磷体系相比,聚苯醚(PPO)和一种磷酸酯阻燃剂配合作用时HIPS的阻燃、抑烟作用以及对力学性能有较大改善作用。 相似文献
6.
对于聚对苯二甲酰对苯二胺(PPTA)和PBT-PTMG体系,比较了溶剂配比(CH2Cl2/NMP)、聚合物浓度、强极性溶剂的用量和加料方式对缩聚反应的影响。发现溶剂配比、基体聚合物PBT-PTMG影响PPTA的转化率和PPTA的分子质量。通过FTIR研究发现PPTA中的酰胺键-NH-和PBT-PTMG的醚键特征吸收均向低渡数位移;通过用PBT-PTMG 的良溶剂二氯甲烷对复合物进行产抽提,结果发现,刚性链PPTA与PBT-PTMG分子链有较强的氢键相互作用,从而改进了分子间的相容性,获得了PPTA/PBT-PTMG的微相复合物。PPTA/PBT-PTMG的微相复合物有较好的力学性能。 相似文献
7.
Jie Bian Weiqiang Wang Congsheng Guan Yonghui Zhao 《北京科技大学学报(英文版)》2005,12(6):572-576
Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis (EPMA) verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding. 相似文献
8.
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10.
超支化聚苯硫醚/聚苯硫醚共混纤维非等温结晶动力学及热性能研究 总被引:3,自引:0,他引:3
使用DSC方法研究了聚苯硫醚(PPS)以及超支化聚苯硫醚/聚苯硫醚共混纤维的非等温结晶动力学,分析了结晶峰值温度等参数,并用Ozawa方程和莫志深方程描述了非等温动力学。结果表明:超支化聚苯硫醚/聚苯硫醚共混纤维的非等温结晶动力学过程能够使用莫志深方程来描述。在共混过程中,少量的超支化聚苯硫醚在线型聚苯硫醚基体材料中能够起到成核剂的作用,提高结晶速率和结晶温度,减少结晶诱导期和半结晶时间。因此,超支化聚苯硫醚/聚苯硫醚共混纤维的结晶速率要快于纯聚苯硫醚纤维的结晶速率。热失重分析表明:超支化聚苯硫醚/聚苯硫醚共混纤维具有与纯聚苯硫醚纤维相同或更优良的热稳定性,添加超支化聚苯硫醚不会降低成品纤维的热稳定性。 相似文献