【作者】 薛英楠；

【导师】 李杨； 唐涛；

【作者基本信息】 大连理工大学 ， 高分子材料， 2009， 硕士

【摘要】 本文通过分子设计的方法合成了结构可控的短链支化聚乙烯,主要调控了分子量和支化含量两个参数,并对得到的样品进行了系统的结构表征。主要工作和结论如下:1、以仲丁基锂为引发剂,通过丁二烯阴离子聚合方法合成了一系列分子量可控、窄分子量分布的聚丁二烯,同时采用四氢呋喃一元调节体系对产物的1,2-结构含量进行了调控。通过GPC、FT-IR和¹H-NMR等表征手段对聚丁二烯的分子量和各种微观结构含量进行了研究,证明聚合物的重均分子量在1至14万范围内可调,分子量分布≤1.15,1,2-结构含量在7.0～29.7mol%之间。采用对甲苯磺酰肼对合成的聚丁二烯样品进行常压非催化加氢反应,得到了模型聚乙烯分子（相当于乙烯/1-丁烯共聚物）,通过FT-IR、高温¹H-NMR、高温¹³C-NMR和高温GPC等手段系统表征了产物的分子结构,结果证明加氢度可达100%,基本不存在副反应,加氢后高温GPC测试的分子量比加氢前常温测试的分子量有所降低。通过DSC分别研究了加氢样品的分子量和支化含量对产物结晶性能的影响,在相同支化含量下,分子量的增加会导致产物熔点和结晶度降低;而在相同分子量下,支化含量的增加也会导致熔点和结晶度的降低。对高1,4-结构含量（≥99.4%）聚丁二烯样品进行加氢反应得到了近乎完全线性的模型聚乙烯。2、采用茂金属催化剂Et[Ind]₂ZrCl₂催化乙烯与1-己烯共聚合反应,通过对聚合条件（温度、共聚单体浓度、Al/Zr比等）的控制,设计合成了分子量10万、支化含量0～5.5mol%的LLDPE系列样品和分子量5万、支化含量7.1～15.1mol%的LLDPE系列样品。通过FT-IR、¹H-NMR、¹³C-NMR、GPC和DSC等手段系统表征了样品的分子结构和结晶性能。结果表明1-己烯是无规插入到聚合物分子链上的,当共聚含量≥8.7mol%时,会出现HH二元组序列。对于10万分子量系列的样品,共聚单体含量的增加会导致熔点和结晶度下降。3、对合成的两种短链支化聚乙烯（加氢聚丁二烯、茂金属乙烯/1-己烯共聚物）以及茂金属均聚聚乙烯与乙烯/1-己烯共聚物共混物进行了流变表征。由于加氢样品条件的限制,没有得到支化含量与流变参数的对应关系;茂金属乙烯/1-己烯共聚物的储能模量、损耗模量和复合粘度随着分子量的增加而增加,随着短链支化含量的增加而降低;没有发现茂金属聚乙烯共混物流变参数与分子结构参数间的确切对应关系。更多还原

【Abstract】 In this dissertation,short chain branched polyethylene with controlled structure was synthesized by molecular design method.The molecular weight and short chain content were mainly controlled and systematic structure characterization of the obtained samples was done. Conclusions were summarized as follows:1.A series of polybutadienes with controlled molecular weight and low molecular weight distribution were synthesized via anionic polymerization using sec-BuLi as initiator. The 1,2-structure content was controlled by THF.The molecular weight and micro-structures were investigated by GPC,FT-IR and ¹H-NMR measurements.It was found that the molecular weight ranged from 10000 to 140000 and the molecular weight distribution was less than 1.15.The 1,2-structure content varied from 7.0 to 29.7 mol%.Then the obtained polybutadienes were hydrogenated by p-toluenesulfonyl hydrazide（TSH） under atmospheric pressure and resulted in model ethylene-butene copolymers.The molecular parameters were investigated by ¹H-NMR,¹³C-NMR,GPC and FT-IR.The results showed that the hydrogenation degree approached 100%without side reactions under proper conditions,but the M_w tested from high-temperature GPC was lower.The effects of M_w and branch content on crystallization properties were studied by DSC.It was showed that the melting point and crystallinity of the hydrogenated samples reduced either by increasing the branch content or by increasing the M_w.Finally,high 1,4-structure content polybutadiene was also hydrogenated to synthesize model linear polyethylene.2.Ethylene was copolymerized with 1-hexene via metallocene catalyst Et[Ind]₂ZrCl₂.By regulating the polymerization conditions,such as temperature,1-hexene concentration and Al/Zr ratios,two series of LLDPEs were obtained:（1） M_w was about 100000 and branch content ranged from 0 to 5.5 mol%;（2） M_w was about 50000 and branch content ranged from 7.1 to 15.1 mol%.The molecular parameters and crystallization properties were investigated by FT-IR,¹H-NMR,¹³C-NMR,GPC and DSC techniques.It was found that 1-hexene unit was isolated between ethylene blocks,and when the 1-hexene content was more than 8.7 mol%,HH diads appeared.The melting point and crystallinity decreased with increasing the 1-hexene content of series（1）. 3.Two kinds of short chain branched polyethylenes,the blends of metallocene homopolyethylene and ethylene/1-hexene copolymers were tested by rheological characterization.No dependence of the molecular structure and the rheolocical properties was found for the hydrogenated polybutadienes because of the limitation of the samples.The storage modulus,loss modulus and complex viscosity of the ethylene/1-hexene copolymers decreased both as the 1-hexene content of the copolymer increased and the molecular weight decreased.No dependence of the molecular structure and the rheolocical properties was found for the PE blends.更多还原