关于氯乙烯悬浮聚合反应的机理及其动力学

本文作者认为乙烯悬浮聚合反应的机理是:PVC 及其大分子自由基不溶解于单体,但能被单体溶胀成为粘胶体,沉析出的处于粘胶体中孤立状态的大分子自由基很难有彼此相遇形成双基链终止(偶合或歧化)的机会,因此 PVC 大分子自由基与粘胶体中的单体发生的链转移反应便成为其唯一的或起主导作用的链终止过程。通过链转移反应,在大分子自由基链终止的同时,形成了单体自由基,后者仍可与粘胶体中的单体发生链的引发、增长及转移等过程。另一方面,由于初级自由基、单体自由基、大分子自由基及单体等的极性与空间位阻作用的影响,使得聚合形成的 PVC 大分子为自由单体首尾相接的链节结构。本文作者按照上述机理进行了一系列高转化率的氯乙烯悬浮聚合反应动力学方程的推导,所推导的动力学方程经过科学实验和生产实践数据的反复验证,证明其是符合客观实际的。

THE MECHANISM AND KINETICS OF VINYLCHLOR IDE SUSPENSION POLYMERIZATION

The mechanism of vinyl chloride suspension polymerization is considered by the present author as that PAC and its growing chain radicals are insolu- ble in their monomer,but they can be swollen by the monomer to form polymer gel.Bimolecular mutual terminations(coupling or disproportionation) of the precipitated growing chain radicals in the polymer gel can not take place.Therefore,the chain transfer between the growing chain radical and monomer will be the only process of termination.On the otherhand,owing to the influences of polarity and steric hindrance of the primary radical, monomer radical,growing chain radical and monomer,the head to tail molecular structure of PVC polymer will be formed. According to the mechanism stated above,the present author has derived the related kinetic equations,and it was proved that these equations are applicable to high conversions with very satisfactory agreements with the practical results of polymerization.