Preparation And Characterization Of Toughened Poly (Vinyl Chloride) Resins

Unplasticized poly(vinyl chloride)(PVC) is brittle and notch-sensitive. In this thesis, organic rubber particles and organic/inorganic particles were applied to toughen PVC Acrylate polymer (ACR) latex particles with poly(butyl acrylate) core and poly(methyl methacrylate) or PVC shell, were synthesized by seeded emulsion copolymerization. ACR-g-VC and ACR-g-VC/nano-hydrotalcite resins, were prepared by vinyl chloride (VC) suspension copolymerization in the presence of ACR latex or ACR latex/nano-hydrotalcite particles, respectively. The particle and fusion characteristics of modified PVC resins, phase structure, mechanical and thermal properties of modified PVC, were investigated.To obtain ACR-g-VC resins with a suitable size and good particle feature, influences of the amount of added ACR latex, the composition and amount of dispersants and the agitation rate on the particle size distribution, internal and external morphology of particles, porosity and pore size distribution of ACR-g-VC resins were studied. It was found that ACR latex had a great effect on the liquid-liquid dispersion and stability of suspension polymerization system. The amount of dispersants added should be correspondingly increased as the amount of ACR latex added increased. When PVA with high alcoholysis degree worked with modified cellulose, the polymerization stability and the regularity of resins particles were improved. ACR-g-VC resins prepared by using PVA-2/modified cellulose composite dispersants had few surface membranes, low degree of primary particle aggregation, and high porosity. ACR-g-VC resins exhibited shorter fusion times than PVC.The structure and properties of ACR-g-VC were characterized by using electron micrography, thermogravimeric analyzer, etc.. It was showed that the rubber phase was uniformly dispersed in PVC matrix, and the compatibility between ACR and PVC was good. The notched impact strength of the ACR-g-VC with 10.5% ACR was 30 times of pure PVC, and the fracture surface of samples exhibited a network drawing. The weight loss rates of ACR-g-VC resins were decreased with the increase of ACR content, while Vicat softening temperature of ACR-g-VC was slightly decreased with the increase of ACR content.The morphology, thermal stability, fusion performance and mechanical properties of ACR-g-VC/nano-hydrotalcite composites prepared by in-situ suspension polymerization, were characterized by using TEM, DMA, thermogravimeter, and torque rheometer, and compared with the ACR-g-VC/nano-hydrotalcite composites prepared by direct mixing. TEM micrographs showed that the dispersion of nano-hydrotalcite in the composites prepared by in-situ polymerization were better than that prepared by direct mixing method. Hydrotalcite particles existed in the form of primary particles. Correspondingly, the impact strengths of composites prepared by in-situ polymerization method were greater than that prepared by direct mixing method. ACR and hydrotalcite could improve the thermal stability and fusion performance of PVC, cooperatively.