共查询到19条相似文献,搜索用时 93 毫秒
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稀土催化合成反式,环化和顺反立构嵌段聚异戊二烯 总被引:1,自引:0,他引:1
采用新型稀土催化体系L3-nLnXn-R3Al-RX,研究了催化体系各组分、室温下再陈沦时间、RX和R3A种类及用量、溶剂种类等因素对异戊二烯聚合的影响。在此基础上,经经环化聚合合成出环化聚异戊二烯,并尝试了异戊二 立构癌段聚合,用I动态力学测试等方法表片了聚合物的结构,合成出含1,4-结构68.1%含环化结构的28.9%,顺-1,4和反-1,4链段的Tg分别为-29℃和70℃的顺反立嵌段聚异戊二 相似文献
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异戊二烯阻聚剂的研究 总被引:2,自引:0,他引:2
本文用膨胀计法研究抗氧剂二乙基羟胺、对叔丁基邻苯二酚和2,2,6,6,-四甲基-4-氧-哌啶氮氧自由基对过氧化二碳酸二(2-乙基已基)酯引发异戊二烯聚合的阻聚作用. 相似文献
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采用负载钛催化剂,在0 ̄30℃下对异戊二烯(Ip)本体沉淀聚合的动力学进行了研究。结果表明,体系在单体相未消失之前为稳态聚合,其稳态聚合速率方程为:Rp=kpf[Ti]0[Al]0[M]0,即在单体相未消失前,Rp为恒量。计算出Ip本体沉淀聚合的表观活化能为29.7kJ/mol,催化剂利用率为20% ̄30%,高于溶液聚合法。 相似文献
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Polymerization of isoprene (IP) with alkyllithium (RLi) catalysts in the presence of amines such as triethylamine (TEA), 1,2-dipiperidinoethane (DPPE) and N,N,N′,N′-tetramethyldiaminoalkanes [(CH3)2N(CH2)nN(CH3)2 where n=1, 2, 3, 4 and 6 (TMDAA)] has been studied. By adding the amines, the polymerization rate of IP was accelerated, and the contents of 3,4- and 1,2-units in the resulting polymers increased. The effects of methylene chain length of the TMDAA on the polymerization were examined. It was found that both the polymerization rates and the microstructure of the polymers depend on the methylene length of the TMDAA. The amines having 2 and 3 methylenes in (CH3)2N(CH2)nN(CH3)2 favoured production of the polymer consisting of predominantly 1,2- and 3,4-units. It was proposed that two types of active sites for the polymerization of IP were produced depending on the number n of the TMDAA. Two types of active species were confirmed to be produced with sec-BuLi in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) depending on the TMEDA/sec-BuLi mole ratios. © 1998 SCI. 相似文献
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研究了异戊二烯在两种金属催化作用下均相线性二聚生成月桂烯的影响因素 ,得到优惠工艺条件 :反应温度 13℃ ,催化剂∶异戊二烯 (mol/mol) =0 .0 5∶1 0 ,胺∶异戊二烯(mol/mol) =0 .0 7∶1.0。对加入失活剂的反应液进行蒸馏处理 ,常压下回收溶剂和未反应的异戊二烯 ,含量分别大于 98%和 96% ;在减压条件下分离出月桂烯 ,含量大于 90 %。回收的溶剂和异戊二烯可以再利用 ,月桂烯的总收率大于 4 0 % ,异戊二烯直接二聚合成月桂烯工艺简单 ,便于放大 相似文献
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Victor A Rozentsvet Valery G Kozlov Elza F Ziganshina Natalya P Boreiko Sergei V Kostjuk 《Polymer International》2013,62(5):817-826
The activity of ZnX2‐based initiating systems (X = Cl, Br, I) in the cationic polymerization of isoprene was studied. The highest activity was achieved when co‐initiator (ZnX2) was solubilized in a minimal amount of strongly coordinating solvent such as diethyl ether or acetone and when trichloroacetic acid was used as an initiator. It is shown that the polymerization rate increased in the series ZnI2 < ZnCl2 < ZnBr2. An increase of initiator concentration and temperature also led to an increase of the polymerization rate. The obtained polyisoprenes did not contain high‐molecular‐weight and insoluble fractions and were characterized by low number‐average molecular weight and relatively narrow molecular weight distribution. Unsaturation of polyisoprene decreased with an increase of monomer conversion and reaction temperature. The unsaturated part of the polyisoprene chain possessed predominantly 1,4‐trans microstructure with regular and inverse addition, whereas the 1,2‐ and 3,4‐isomers were present as minor components. It is shown that the synthesized low‐molecular‐weight polyisoprenes are effective plasticizers for rubber compounds in the manufacture of tyres. © 2012 Society of Chemical Industry 相似文献