排序方式: 共有77条查询结果,搜索用时 15 毫秒
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聚合条件对N-羧基-L-丙氨酸-环内酸酐开环聚合产物分子量的影响 总被引:3,自引:0,他引:3
用光气法制备了N-羧基-L-丙氨酸-环内酸酐(L-Alanine NCA).系统研究了L-Alanine NCA开环聚合反应过程中引发剂、溶剂、温度对聚合物分子量的影响.用硝基苯作溶剂,三乙胺作引发剂,所得聚合物特性粘度[η]=1.18.实验中发现,L-Alanine NCA可以顺利地进行热聚合反应。反应具有速率快,转化率高,分子量大的特点。甲苯溶剂中反应5小时所得聚合物[η]=2.35,高于采用引发剂的聚合体系产物的相应值。 相似文献
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桑蚕丝素蛋白的结构、形态及其化学改性 总被引:4,自引:0,他引:4
通过对桑蚕吐丝机构的描述,着重从高分子科学的角度介绍桑蚕丝和蚕丝素蛋白大分子的组成、形态及各种化学、物理性质,讨论了蚕丝素蛋白的纤维化机理,并简述了丝索蛋白纤维的化学接枝改性及其应用。 相似文献
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研究了几种O-酰基肟酮在313nm和365nm光照下引发丙烯腈和甲基丙烯酸甲酯光聚合。在低吸光度时,聚合速度对引发剂浓度符合0.5次方指数关系,而在高吸光度时,聚合速度、聚合物分子量都与引发剂浓度无关。引发剂消光系数越大,出现其指数为零的浓度越低。 相似文献
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The molecular weight distribution function (MWD) of AB, B type condensation polymers obtained by adding AB monomers in batches has been derived by statisticaland kinetic methods. Calculations show that the MWD of condensation polymers obtained by this process is much narrower than the Flory distribution and agrees with the Monte Carlo results very well. 相似文献
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The reactive intermediate cyclopropylidene, generated quickly by the reactions of dihalocyclopropanes with lithium or magnesium under ultrasonic irradiation, can be trapped by olefins and the corresponding spriopentane derivatives are obtained, Based on the identification of the intermediate and the products of the reaction, a mechanism is proposed that the radical intermediate should be generated at first via a single electron transfer process, sequentially it gains another electron from the metals to form the carbenoid intermediate which then leads to the main products by insertion, addition or rearrangement. On the other hand, it can also abstract the hydrogen atom from the solvent to form the corresponding monohalide which then converts into the cyclopropane derivatives. Discussions on and verifications for the reaction mechanism are given in this paper. 相似文献
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用红外光谱、核磁共振和示差扫描量热分析等手段对聚酰胺-46进行了基本表征,并用广角X射线衍射和扫描隧道电子显微镜技术对其聚集态结构进行了分析. 相似文献