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本工作研究了异戊二烯在己烷中用Ln(naph)_3-Al(i-Bu)_2H-Al_2Et_3Cl_3催化剂的聚合,发现催化剂呈非均相,聚合物分子量很低,在高Al(i-Bu)_2H浓度下,对Al(i-Bu)_2H的链转移速度与其浓度不成正比。分子量数据表明,链转移是与吸附在催化剂表面上的Al(i-Bu)_2H相关,可用Langmuir吸附等温式描述,因此,可以认为,链转移是在催化剂表面上吸附的Al(i-Bu)_2H与增长链之间发生的。测得对Al(i-Bu)_2H的链转移速度常数k_a为8.3秒~(-1)(60℃)。
In this work, we investigated the polymerization of isoprene in hexane using Ln (naph) _3-Al (i-Bu) _2H-Al_2Et_3Cl_3 catalyst. The results showed that the catalyst was heterogeneous and the molecular weight of the polymer was very low. -Bu) _2H, the chain transfer rate of Al (i-Bu) _2H is not proportional to its concentration. Molecular weight data indicate that chain transfer is related to Al (i-Bu) 2 H adsorbed on the surface of the catalyst and can be described by Langmuir adsorption isotherm. Thus, it is believed that chain transfer is the adsorption of Al (i-Bu) on the catalyst surface, What happened between _2H and growth chain. The chain transfer rate constant k_a for Al (i-Bu) _2H was determined to be 8.3 seconds -1 (60 ° C).