双水相中低相对分子质量聚丙烯酸钠的合成

实验以聚乙二醇/聚乙烯醇的混合物为分散剂,以过硫酸钾-尿素为引发体系,以甲酸钠为相对分子质量调控剂,在双水相中进行丙烯酸的聚合反应,制备相对分子质量为3 000～4 000的聚丙烯酸钠。考察了分散体系、引发体系、添加剂等因素对聚合反应的影响。结果表明:以聚乙二醇-聚乙烯醇为分散剂,m(PEG):m(PVA)=1.8:1,质量分数为5.0%～5.5%;以过硫酸钾-尿素为引发剂,n(K_2S_2O_8):n(CO(NH_2)_2)=1:1.5;n(K_2S_2O_8):n(AANa)=0.07:1;甲酸钠为丙烯酸钠聚合反应控制剂,质量分数为1%。于50～55℃,进行双水相中丙烯酸钠的聚合反应,单体转化率达99.6%,黏均相对分子质量可控制在3 000～3 600。双水相中制备的聚丙烯酸钠用于陶瓷铁粉的分散实验,表明分散性能较好。

SYNTHESIS OF LOW MOLECULAR WEIGHT SODIUM POLYACRYLATE IN AQUEOUS TWO-PHASE SYSTEM

Low molecular weight sodium polyacrylate was prepared via an aqueous two-phase polymerization method.The effects of composition of dispersing agent,initiator system and additives on the polymerization have been investigated.The optimum conditions were found as follows:polyethylene glycol-polyvinyl alcohol at the mass ratio of 1.8:1 and total mass concentration of 5.0%-5.5% as dispersing agent; potassium persulfate-urea as initiator system; the molar ratio of potassium persulfate to urea of 1:1.5 and potassium persulfate to sodium acrylate of 0.07:1;1% sodium formate as controlling agent for sodium acrylate polymerization; and the reaction temperature 50-55℃.When sodium acrylate was polymerized in the aqueous two-phase under these conditions,the monomer conversion was up to 99.6%,with the viscosity-average molecular weight of the polymer being controlled between 3 000-3 600.The sodium polyacrylate obtained has been used for the dispersion of ceramic ferro powder and showed good dispersability.