偏氯乙烯-丙烯腈-苯乙烯共聚物颗粒发泡行为研究

用显微镜实时监测实验方法研究了偏氯乙烯 (VDC) 丙烯腈 (AN) 苯乙烯 (St)共聚物颗粒的发泡行为 ,考察的影响因素包括共聚物组成、发泡剂浓度、颗粒粒径、发泡温度等 .实验发现 ,共聚物中AN或St单元含量提高 ,发泡速率降低 .提高发泡温度或增加发泡剂浓度 ,均加快发泡速率 .由于在聚合物颗粒发泡时存在发泡剂损失 ,小粒径的VDC AN St共聚物颗粒发泡速率快 .当颗粒发泡生长较快时 ,发现有生长过头现象 ,这可能是由惯性生长造成的

STUDY ON THE EXPANDING BEHAVIOR OF VINYLIDENE CHLORIDE-ACRYLONITRILE-STYRENE TERPOLYMER PARTICLES

The expanding behavior of vinylidene chloride(VDC)-acylonitrile(AN)-styrene(St) terpolymer particles containing 1-fluoro-1,1-dichloroethane(HCFC-141b) was monitored on line by a microscope equipped with a heating apparatus and an automatically photographing system.Effects of the factors such as copolymer composition,expanding temperature,concentration of blowing agent and particle size on the expanding behavior were investigated.It was found that an increase of AN or St units in VDC-AN-St terpolymer led to a decrease of expanding rate of particles.The expanding rate of VDC-AN-St copolymer particles increased with the increase of temperature and concentration of blowing agent,and decreased with the increase of the size of VDC terpolymer particles due to the loss of blowing agent to the surroundings.An “overshoot" phenomenon of particle growth was observed at high expanding rate,which may be attributed to the existence of inertia growth in free expansion of polymer particles.