沉淀聚合制备低分子量聚丙烯酸及残液循环利用

Precipitation Polymerization of Low Molecular Weight Acrylic Acid and Recycling of Polymerization Residue

摘要:

以偶氮二异丁腈(AIBN)为自由基引发剂，石油醚为溶剂，异丙醇为链转移剂，通过沉淀聚合获得了低分子量的聚丙烯酸固体。考察了引发剂用量、链转移剂用量、单体浓度对聚合收率的影响，确定最佳聚合条件为： AIBN用量为单体质量的10%，链转移剂为单体质量的100%，单体浓度100 g/L, 反应温度80 ℃，反应时间4h。反应结束后产品在底部沉淀析出，溶剂直接循环利用，在最佳聚合条件下，残液循环利用5次，单体的累计转化率达到92.6%。凝胶渗透色谱(GPC)分析表明，残液循环利用得到的产品质均分子量(Mw)变化不大，保持在1000~1300，多分散性(PDI)为1.92~3.38。

Abstract:

The low molecular weight acrylic acid was synthesized by precipitation polymerization in petroleum ether utilizing azo-bis-isobutyronitrile (AIBN) as a free radical initiator and isopropanol as chain transfer agent. The influences of monomer concentration, initiator and chain transfer agent amount on the yield of polyacrylic acid are investigated. And the results showed the optimal polymerization conditions were that: the mass percent of initiator (AIBN) was 10% relative to monomer, the chain transfer agent was 100% relative to monomer, the monomer concentration was 100 g/L, and at 80 ℃ for 4h. Product was precipitated in bottom and the solvent can be removed and recycled. A monomer conversion of 92.6% was achieved after the residue was recycled for 5 cycles under the optimized polymerization conditions. The results of the gel permeation chromatography (GPC) showed that the weight average molecular weight (Mw) of polyacrylic acid was kept at 1000~1300 with minimal change and a polydispersity index (PDI) of 1.92~3.38 was obtained.