氯乙烯与甲基丙烯酸- 2-羟乙酯乳液共聚研究

对氯乙烯5甲基丙烯酸-2-羟乙酯(VC-HEMA)乳液共聚的稳定性、动力学和组成控制进行了研究。发现:由于反应过程中HEMA主要分配在水相,对乳化剂十二烷基硫酸钠有强烈增溶作用,并存在HEMA水相聚合,使乳液聚合稳定性随HEMA/H2O比增大而降低。随投料单体中HEMA含量增加,共聚速率和聚合转化率降低。得到了VC-HEMA共聚竞聚率为rVC=0.0123,rHEMA=18.53,乳液共聚表观竞聚率r'VC=0.341,r'HEMA=4.29。VC-HEMA间歇乳液共聚得到的共聚物组成极不均匀,采用多步添加HEMA的半连续乳液共聚,合成了组成较均匀、HEMA质量分数在10%以下的共聚物。

Emulsion Copolymerization of Vinyl Chloride and 2- Hydroxyethyl Methacrylate

Polymerization stability, kinetics and control over copolymer compositions were investigated for vinyl chloride and 2- hydroxyethyl methacrylate (VC and HEMA) emulsion copolymerization system. The greater aqueous solubility of HEMA resulted in the increase of the solubility of sodium dodecylsulfate (SDS) in water, and aqueous polymerization of HEMA, so the latex became unstable as the feeding ratio of HEMAH2O increased. The copolymerization rate decreased with increase of HEMA fraction in the feeding monomers. The reactivity ratios of VC and HEMA in bulk copolymerization were obtained as rVC=0.0123,rHEMA=18.53, while the apparent reactivity ratios of VC and HEMA in emulsion copolymerization were obtained as r'VC=0.341, r'HEMA=4.29. The composition of VC- HEMA copolymer varied significantly with conversion in the batch emulsion coplymerisation, while the copolymer with more uniform composition could be prepared by semi- continuous emulsion copolymerization.