共查询到20条相似文献,搜索用时 93 毫秒
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研究了聚合温度在30~60℃,以正丁基锂为引发剂、环己烷为溶剂、二硫化碳为结构调节剂的异戊二烯负离子聚合的反应规律,以及二硫化碳用量和聚合条件对聚异戊二烯微观结构的影响。结果表明,随着异戊二烯/环己烷的增加,聚异戊二烯中的顺式-1,4-结构含量降低;随着引发剂浓度的增加,顺式-1,4-结构含量也降低;随着反应温度升高,顺式-1,4-结构含量先增加后降低;随着二硫化碳用量的增加,顺式-1,4-结构含量先增加后略有降低。在50℃、异戊二烯/环己烷(质量比)为1/9、正丁基锂/异戊二烯(摩尔比)为0.68×10-3及二硫化碳/正丁基锂(摩尔比)为0.08×10-3时可制得顺式-1,4-结构摩尔分数最高约为96%的高顺式聚异戊二烯。 相似文献
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大连理工大学化工学院高分子材料系研究了聚合温度在30~60℃,以正丁基锂为引发剂,环己烷为溶剂,二硫化碳为结构调节剂的异戊二烯负离子聚合的反应规律,以及二硫化碳用量和聚合条件对聚异戊二烯微观结构的影响。结果表明,随着异戊二烯/环己烷质量比增大,聚异戊二烯中的顺式-1,4结构含量降低;随着引发剂浓度增大,聚异戊二烯中的顺式-1,4结构含量减小; 相似文献
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用动态酰化法测定聚醚中的伯羟基 总被引:1,自引:0,他引:1
作为聚氨酯泡沫塑料的主要原料聚醚,系由环氧乙烷和环氧丙烷聚合而成。环氧丙烷聚醚的端基为仲羟基,用环氧乙烷加成聚环氧丙烷聚醚的末端可制得伯羟基聚醚,据有关文献报道,含伯羟基高的聚醚在发泡过程中,活性大,熟化时间短,并能提高产品的阻燃性能和泡沫体的回弹性。因此,三官能团聚醚中,伯羟基的含量是一个重要指标,必须加以测 相似文献
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北京化工研究院燕山分院以环己烷为溶剂,苯乙烯(St)、丁二烯(Bd)以及异戊二烯(Ip)为单体,正丁基锂为引发剂,采用负离子聚合法合成了集成橡胶——星形苯乙烯-异戊二烯-丁二烯嵌段共聚物(SIBR),考察了星形SIBR的相对分子质量、侧基含量、嵌段比(即Ip的均聚物链段与 相似文献
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中国石油大连润滑油研究开发中心采用阴离子聚合法,以正丁基锂为引发剂,先合成了线形异戊二烯-苯乙烯嵌段活性链;再以二乙烯基苯(DVB)为偶联剂,采用分次滴加法合成了星形异戊二烯-苯乙烯嵌段共聚物。 相似文献
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以正丁基锂为引发剂,环己烷为溶剂,双四氢糠丙烷为结构调节剂,四氯化锡为偶联剂,采用负离子聚合法合成了锡偶联型苯乙烯-异戊二烯-丁二烯三元共聚物(SIBR)。通过核磁共振波谱仪、差热分析仪及黏弹谱仪等对聚合产物的微观结构、玻璃化转变温度、力学性能及动态力学性能等进行了分析测试。结果表明,随着双四氢糠丙烷与正丁基锂摩尔比的增大,SIBR中的1,2-聚丁二烯和3,4-聚异戊二烯结构含量明显增加,而1,4-聚丁二烯和1,4-聚异戊二烯结构含量明显减少;侧基含量和玻璃化转变温度均明显升高;0℃的损耗因子明显增大,而60℃的损耗因子均小于0.12;总体上对SIBR硫化胶力学性能的影响不大,SIBR硫化胶的拉伸强度均超过了19 MPa,300%定伸应力大于12 MPa,扯断伸长率大于350%,能够满足高性能轮胎对胎面胶的要求。 相似文献
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Summary Star-shaped block copolymers PCL-b-PMMA and PCL-b-PSt were successfully synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) on the basis of hydroxyl-terminated cyclotriphosphazene. The star-shaped PCL was synthesized by bulk polymerization of ε-caprolactone with hydroxyl-terminated cyclotriphosphazene initiator. Star-shaped PCL was converted into a macroinitiator via esterification with 2-bromopropionyl bromide. Star-shaped block copolymers could be obtained by ATRP of methacrylate (MMA) and styrene (St). The molecular weight of these star-shaped block copolymers could be adjusted by the variation of monomer conversion. 相似文献
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负载钛-三乙基铝体系催化异戊二烯聚合 总被引:1,自引:0,他引:1
以负载钛(TiCl4/MgCl2)为主催化剂、三乙基铝为助催化剂催化异戊二烯聚合,研究了n(Ti)/n(Ip)、n(Al)/n(Ti)及温度等对单体转化率和催化效率的影响。采用FTIR和1H-NMR对聚合产物的微观结构进行测试表征,DSC测定聚合产物的熔点和结晶度。结果表明,所得聚合产物为反式-1,4-结构摩尔分数达98%的异戊橡胶;聚合体系的单体转化率随n(Ti)/n(Ip)的增大而升高,催化效率则先升高后降低;随n(Al)/n(Ti)和聚合温度的增大,催化效率和单体转化率均先升高后降低,最佳n(Al)/n(Ti)值为110~120,最佳聚合温度为20~25℃。 相似文献
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Summary By anionic polymerization in cyclohexane with secbutyllithium as initiator polyisoprene and poly (styrene-b-isoprene-b-styrene) have been prepared with 92 mole % and 90 mole % cis-1, 4 isoprene structural units respectively. From the13C NMR spectrum there is no evidence for chain reversals of the polyisoprene chain, which was claimed to prevent crystallization in lithium polyisoprenes in the unstretched state. By DSC it is shown that the polyisoprene sample crystallizes in the isotropic state at –25°C. The block copolymer shows stress induced crystallization as demonstrated by temperature dependent stressstrain measurements.Dedicated to Prof. Dr. G. Rehage on the occasion of his 60th birthday 相似文献
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Star-shaped polymers that consist of well-defined polystyrene (PS) arms were successfully synthesized in high yield by coupling
reaction between multifunctional core molecules and hydroxyl-terminated PS in the presence of 1, 3-dicyclohexylcarbodiimide
and 4-(dimethylamino) pyridine at room temperature. Several systems were investigated: (1) Pyromellitic dianhydride (PMDA)
and hydroxyl-terminated PS (PS-OH) with narrow molecular weight distribution, which was prepared by atom transfer radical
polymerization (ATRP) of St with 2-hydroxyethyl bromoisobutylate (HEBiB) as initiator. (2) PMDA and PS-OH prepared by conventional
free radical polymerization, with 2-mercaptoethanol as chain transfer agent. (3) Narrow molecular weight distributed alternating
copolymer of maleic anhydride (MA) and styrene (St), which was obtained via reversible addition fragmentation chain transfer
polymerization (RAFT) process, and PS-OH obtained by ATRP. The formation of star-shaped PSs was confirmed by proton nuclear
magnetic resonance (1H NMR) and gel permeation chromatography (GPC). 相似文献
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VO(P_(204))_2/烷基铝合成低分子量3,4-聚异戊二烯 总被引:2,自引:0,他引:2
以VO(P_(204))_2/烷基铝为催化体系,对异戊二烯进行聚合,考察了不同烷基铝、铝/钒物质的量比、陈化时间和聚合温度对聚合的影响.结果表明:VO(P_(204))_2-Al(Oct)_3催化体系在己烷中,铝/钒物质的量比为4.0,于40 ℃下的聚合物收率大于40%.所得聚合物的数均分子量为1.35×10~4 g/mol,分子量分布为3.1;其微观结构中含有约50%的3,4-结构单元,并且聚合条件对产物的微观结构无显著影响. 相似文献
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