硫氰化钠对过氧化物引发丙烯腈水溶液聚合的影响

<正> 关于硫氰化物对丙烯腈聚合的影响,早期的报道认为对过硫酸盐引发丙烯腈水溶液聚合时,硫氰化钾起阻聚作用.但丙烯腈在浓硫氰化钠水溶液中,可顺利地用偶氮双异丁腈(AIBN)、光、叔丁基过氧化氢(TBH)或TBH-醇胺引发聚合,在这些聚合反应中硫氰化钠无阻聚或缓聚作用.为了弄清硫氰化钠的影响,我们比较系统地研究硫氰化钠对丙烯腈水溶液聚合的影响.实验结果表明,其影响与所用的引发剂有关.如用TBH时,硫氰化钠起活化作用,缩短反应的诱导期,提高聚合速度与转化率,30—50℃

THE INFLUENCE OF SODIUM THIOCYANATE ON PEROXIDE INITIATED AQUEOUS POLYMERIZATION OF ACRYLONITRILE

Initiation of acrylonitrile(AN) polymerization in the aqueous solution of sodium thiocyanate by different peroxides was studied. It was found that the structure of peroxides play an important role, if TBH or H2O2 was used as initiator. Addition of small amount of NaSCN would act as activator, the induction period will be shortened as the concentration of NaSCN gradually increases. In case of TBH, percentage of conversion would increase at the same time, so TBH, could be applied to both concentrated NaSCN aqueous solution polymerization and plain aqueous solution polymerization. In case of H2O2, percentage of conversion would decrease at the same time, so H2O2 could be applied only to aqueous solution polymerization but not to concentrated NaSCN aqueous solution polymerization. Within the temperature range of 30-50℃, activation energies of TBH and H2O2 in initiating aqueous polymerization of AN in the presence of some NaSCN were determined to be 63.6 and 66.9 KJ.mol-1 respectively. For KPS, the presence of NaSCN would always show its inhibition effect in increasing induction period and lowering percentage of conversion.