【摘要】 本工作研究了丁二烯在乙酰基丙酮镍-一氯二烷基铝体系中聚合的一般规律、聚合动力学及链转移过程。实验结果表明:聚合速率对单体浓度、主催化剂（镍络盐）浓度均呈一级关系,而对一氯二异丁基铝浓度呈二级关系,即 -（dM/dt）=k[M][NiA₂][Al（i-C₄H₉）₂Cl]²对一氯二乙基铝浓度则呈1/2级关系,即 -（dM/dt）=k[M][NiA₂][Al（C₂H₅）₂Cl]^1/2对这二种体系反应级数的不同作了解释。 实验测得丁二烯在乙酰基丙酮镍-一氯二异丁基铝体系中聚合的总活化能为8.0±0.5千卡/克分子,而在一氯二乙基铝体系中为 8.9±0.5千卡/克分子。 研究了丁二烯在本体系中聚合时单体浓度、主助催化剂浓度、聚合转化率、溶剂以及某些添加剂等因素对聚合物分子量的影响。结果表明:聚合物的分子量随单体浓度的增大而增大;随镍组份浓度的增大而减小;当体系中水分含量很低时,一氯二乙基铝浓度的改变对聚合物分子量基本无影响;在5—60％转化率及0—35℃范围内聚合物分子量变化不明显;庚烷中所得聚合物的分子量比苯中所得者低;添加水、吡啶、三溴化铝、三乙基铝、甲基环己烷及蒽等都不能显著提高聚合物的分子量。 计算链转移常数,得到对含镍组份为 84,对单体为 1.9× 10^-3,终止常数为 2.3×10^-3。因而得知本体系中主要的链转移过程是?更多还原

【Abstract】 The kinetic aspects and chain transfer processes of the stereospecific polymerization of butadiene initiated by catalyst systems consisting of nickel acetylacetonate and dialkyl aluminium chloride have been studied. It has been shown that the rate of polymerization is first order with respect to both monomer and nickel acetylacetonate concentrations, but second order with respect to the diisobutylaluminium chloride concentration. Thus the polymerization rate with diisobutylaluminuim chloride system is expressed as-dM/dt=k[M][NiA2][Al(i-C4H9)2Cl]2 When diethylaluminium chloride instead of diisobutylaluminium chloride is used, the rate of polymerization is 1/2 order in diethylaluminium chloride concentration, that is,-dM/dt=k[M][NiA2][Al(C2H5)2Cl]1/2 On the basis of these results, a possible polymerization mechanism of these two systems is proposed. The overall activation energy of polymerization has been determined to be 8.0±0.5 kcal/mole for the NiA2-Al(i-C4H9)2Cl system, and 8.9±0.5 kcal/mole for the NiA2-Al(C2H5)2Cl system. Effects of monomer concentration, catalyst concentration, conversion, solvent, and additive compounds on the polymer molecular weight were also studied. Variation of temperature from 0-35° has no significant effect on the molecular weight of polybutadiene obtained, indicating that the difference in activation energy, Ep-Et, is small. Values of chain transfer and termination constants are also presented. It appears that transfer to nickel-containing compound is the main chain transfer reaction in this system.更多还原