P(nBA-co-St)接枝VC反应中的缓聚及复合物结构与性能

采用丙烯酸正丁酯与苯乙烯共聚物P(nBA-co-St)胶乳为种子,通过乳液接枝共聚氯乙烯(VC)制备了P(nBA-co-St)/PVC复合树脂。粒径分析结果表明,PVC已成功地包覆在种子上,从透射电镜照片能清楚分辨出复合粒子具有核壳结构,文中合理解释了在该接枝共聚过程中显现的缓聚现象。动态力学分析结果表明,随着核层共聚物中PSt组分含量增加,复合材料在低温区的力学损耗峰逐渐移向高温方向,纯PnBA核因比PSt组分更易接枝VC,从而显著影响了复合树脂低温区的玻璃化转变温度。试样冲击断面的扫描电镜分析揭示,P(nBA-co-St)原位增韧PVC的机理源于基体的剪切屈服。

Retardation Polymerization of P(nBA-co-St) Latexes-Grafted VC and Structure & Properties of P(nBA-co-St)/PVC Composites

P(n-butyl acrylate-co-styrene)/poly(vinyl chloride)[P(nBA-co-St)/PVC]composite resins were prepared via seeded emulsion copolymerization of vinyl chloride(VC) using n-butyl acrylate(nBA) and styrene copolymer latex as seeds.Diameters and morphology of latex particles were characterized by laser particle size analyzer,SEM and TEM.The results demonstrate that the PVC chains successfully covered onto the P(nBA-co-St) seeds.A phenomenon of retardation polymerization appeared in VC graft copolymerizing the P(nBA-co-St) was reasonably explained.Pure PnBA core greatly influenced Tg of the composite resin in the low-temperature transition region.This result should stem from the different degrees of PnBA-or PSt-grafted PVC to cause the difference of the graft copolymer content in the resin.The fractured surface for the P(nBA-co-St)/PVC sample with 75/25 mass ratio of nBA to St units showed a "root or beard" morphology.SEM analysis confirms that toughening mechanism in the materials derives from the shear yielding of the PVC matrix.