化学学报 ›› 1963, Vol. 29 ›› Issue (1): 19-27. 上一篇    下一篇

论文

从分子量分布研究高聚物溶液的超声裂解动力学

朱善農, 錢人元   

  1. 中国科学院化学研究所
  • 投稿日期:1962-04-27 发布日期:2013-06-03

KINETICS OF ULTRASONIC DEGRADATION OF MACROMOLECULES IN SOLUTION BY MOLECULAR WEIGHT DISTRIBUTION STUDIES

CHU SHAN-NONG, CHIEN JEN-YUAN   

  1. Institute of Chemistry, Academia Sinica
  • Received:1962-04-27 Published:2013-06-03

用超离心机沉降速度法,在θ-溶剂中测定经不同超声裂解时间的聚甲基丙烯酸甲酯裂解产物的分子量分布,从此计算出数均及重均分子量等数据,对裂解过程中分子量分布的改变与裂解动力学规律进行探讨。1.考虑试样多分散性及裂解过程中的分子量分布对裂解速率权重因子的影响,并用数论方法逐阶段计算超声裂解产物的分子量分布曲线,与各种裂解机构的计算结果比较,以Ovenall的断键规律与实验有良好的符合。而Jellinek,Mostafa的断键规律以及Bueche的切断位置恰在高分子键中间的近似计算方法等均与实验数据偏差颇大。2.Ovenall动力学方程在裂解后期,与实验结果偏差较大,需要修正。3.高分子经超声裂解断鏈后的最小聚合度必须大于e,实验数据说明这e值不可能分布很宽。4.计算一个单分散试样(聚合度为9×103)在裂解过程中的分子量分布的变化,其图形不同于Jellinek,Mostafa及Sata等推导的结果。

Despite of quite a considerable amount of theoretical and experimental studies on the kinetics of ultrasonic decisive conclusions about the scheme of bond scission and degradation kinetics have been reached.In view of the recent advances in the determination of molecular weight distribution (MWD) by the method of sedimentation velocity in a θ-solvent,the present authors attempted to attack this problem by MWD studies during the course of degradation process.A benzene solution of polymethylmethacrylate fraction of Mn =9.4 X 105 was used.Six samples were irradiated in ultrasound of 1 megacycles/sec for various durations.The MWD curves of these samples were determined in acetone-ethanol mixed solvent at θ-temperature.Number average molecular weights were calculated from the MWD data.