聚辛烯-1Mark-Houwink常数的确定及其分子量分布研究

本文用GPC结合特性粘度的方法,对聚辛烯-1四氢呋喃体系的Mark-Houmink常数进行订定。数据处理采用了Weiss法和流体力学平均分子量(?)_x两种方法,α值分别为0.701和0.625,相对误差10％左右,所得Mark-Hon-Wink方程Weiss法为:η]_(THF)~(25℃)=3.89×10~(-4)M]~(0.701)(?)_x法为η]_(THF)~(℃25)=4.14×10~(-4)M~(0'625)。本文还研完了聚合反应条件对聚辛烯-1分子量及分子量分布的影响。发现三种TiCl_3为主催化剂,三乙基铝为助催化剂时,其GPC谱图均为双峰型,两个峰的比例随聚合反应条件不同而变化。表明聚合体系至少有两种不同性质的活性中心,有着不同的形成和增长速率。

EVALUATION OF MARK-HOUWINK CONSTANTS AND STUDY OF THE MOLECULAR WEIGHT DISTRIBUTION OF POLY (1-OCTENE)

The Mark-Houwink constants of poly (1-octene) in THF at 25℃ were evaluated from GPC and η] of broad distribution samples. Two methods were used: calculation of K and a from the method developed by weiss and from the linear relation between in Inη] and InMx made by Goldwasser. More reliable results were obtained with the latter method. Determination of the molecular weight was made with the light scattering method, which gave Mw value close to that obtained from GPC. Then the Mark-Houwink equation for poly(l-octene) is THF 25℃= 4.14×10-4 M0.625. The effects, of polymerization conditions on molecular weight distribution were studied with GPC. When AlEt3 was used as cocatalyst, the distribution was bi-modal. The change of alkyl aluminiums caused greater effect on the distributions than the change of TiCl3 strucure.