丙烯腈与衣康酸在DMSO/H_2O中的聚合及聚合物性能表征

STUDY ON COPOLYMERIZATION AND PROPERTIES OF P(AN-co-IA) SYNTHESIZED IN DMSO/H_2O

采用丙烯腈 (AN)与衣康酸 (IA)为共聚单体 ,以偶氮二异丁腈为引发剂在混合介质二甲基亚砜 水(DMSO H2 O)中自由基沉淀共聚合 ,合成了高分子量的聚丙烯腈 .通过正交设计方法研究了聚合反应条件 ,如反应温度、单体浓度、混合介质DMSO H2 O配比等对聚合反应的转化率的影响 ,还重点探讨了混合介质DMSO H2 O配比对转化率和粘均分子量的影响 .采用DSC ,TG ,IR等手段研究了PAN均聚物及 (PAN co IA)的结构与性能 .研究结果表明 ,增加反应温度 ,降低单体浓度 ,降低喂料AN IA配比中IA的含量 ,均有利于提高聚合反应的转化率 .AN与IA共聚反应的转化率随着反应介质中DMSO含量的增加而降低 ,同时聚合物的粘均分子量也降低 .对于喂料AN IA配比中IA含量相同的P(AN co IA)共聚物 ,高分子量P(AN co IA)共聚物比常规低分子量的放热峰起始温度低 。

High molecular weight polyacrylonitrile ( PAN) was obtained by the free-radical suspension copolymerization of itaconic acid (IA) and acrylonitrile ( AN) which was carried out in DMSO/ H2O using azodiisobutyronitrile(AIBN) as initiator. Orthogonal design method was used to study the effect of polymerization parameters, such as the reaction temperature, monomer concentration, DMSO/H2O ratio, initiator content and so on, on the conversion of polymerization. The reaction temperature is the most important factor determining the conversion of copolymerization. The effect of DMSO/H2O ratio on the conversion and viscosity-average molecular weight was specially introduced. The copolymerization reaction rate and the viscosity- average molecular weight of copolymers may decrease as the result of the high chain transfer constant of DMSO. For copolymerization of AN, and IA, with the inclusion of good solvent DMSO, the solution degree of AN in DMSO/H2O is higher than in water., as a result, the resulting copolymer pellets becomes porous. The structure and properties of PAN homopolymer and P (AN-co-IA) copolymer were also studied by using DSC, TG and IR measurements. It was shown that the conversion of polymerization could be increased by increasing reaction temperature, decreasing monomer concentration and decreasing the. IA content in the feed AN/IA ratio. The results also demonstrated that the conversion of copolymerization of IA and AN decreased with the increase of DMSO content in the feed DMSO/H2O ratio. For the same IA content in the feed AN/IA ratio,the high molecular weight P(AN-co-IA) copolymers have the lower start exothermal reaction temperature and wider DSC exothermal peak as compared to the convertional low molecular weight P(AN-co-IA) copolymers,and these phenomena are consistent with the result of IR studies.