一、引言从文献中知道,丙烯腈均聚物的分级,已有許多人研究过,而丙烯腈共聚物的分級,还沒有看到报导。但这一工作具有实际意义。从文献中知渲,丙烯腈均聚物的分级,多采用二甲基甲酰胺为溶剂,庚烷为沉淀剂(1)(2)(3)(4)(5)。我們对这个体系作了实驗。在实驗中发現,二甲基甲酰胺与庚烷,在一般溫度下要分层,不万溶,只有在60℃以上才能互溶。而溫度高,对分级带来很多麻煩,如,引起高聚物的交联、降解等。于是,我們就想找寻别的体系。通过实驗摸索,认为二甲基甲酰 I. INTRODUCTION It has been known from the literature that the classification of acrylonitrile homopolymers has been studied by many people and the classification of acrylonitrile copolymers has not been reported yet. But this work is of practical significance. From the literature known rendering, acrylonitrile homopolymer grading, the more the use of dimethylformamide as a solvent, heptane precipitant (1) (2) (3) (4) (5). We experimented with this system. In the experiment found that dimethyl formamide and heptane, in general temperature to stratification, not Wan Rong, only above 60 ℃ to mutual solubility. The high temperature, to grading caused a lot of trouble, such as, caused by the polymer crosslinking, degradation and so on. So, we want to find another system. Through experimental exploration, that dimethylformamide