甲基丙烯酸甲酯光引发聚合中的初级自由基终止效应

本文研究了甲基丙烯酸甲酯在30℃时的光引发聚合。当光强较强时,聚合速率和光强的平方根不呈线性关系,聚合速率略低于经典动力学关系式所预示的数值。粘均聚合度的倒数和聚合速率也不呈线性关系。在考虑了初级自由基的终止反应后,这些偏离都得到了合理的解释。 比较甲基丙烯酸甲酯在30℃的光引发聚合和在60℃的过氧化苯甲酰引发聚合的数据,可以看出,初级自由基的终止效应在低温时更为重要。

THE PRIMARY RADICAL TERMINATION IN THE PHOTOPOLYMERIZATION OF METHYL METHACRYLATE

The bulk photopolymerization of methyl methacrylate at 30℃ was studied. In case of stronger light intensity, the rate of polymerization is no longgr proportional to the square root of light intensity. And a plot of the reciprocal of viscosity-average degree of polymerization against rate of polymerization is an upward curve rather than a straight line. These results are discussed in terms of primary radical termination reactions.By comparing the data of the photopolymerization of methyl methaerylate at 30℃ with those of benzoyl peroxide initiated polymerization at 60℃, it clearly shows that primary radical termination is more important at lower temperature than at higher temperature.