Preparation And Characterization Of Poly(Vinyl Chloride)/Nanometer Hydrotalcite Composites

Hydrotalcite is a new anionic layered inorganic material, which can improve the thermal stability, fire-resistance and smoke-suppression of poly(vinyl chloride) (PVC). In order to improve the dispersion homogeneity, decrease the dispersion size of nanometer hydrotalcite in PVC matrix, and obtain PVC/hydrotalcite nanocomposite with excellent properties, the new preparation methods, including the synthesis of PVC/nanometer hydrotalcite composite resin by in-situ suspension polymerization, blending of PVC with acrylate polymer/sodium dodecyl sulfonate intercalated hydrotalcite (ACR/SDS-HT) composite, were investigated. The structure and properties of PVC/hydrotalcite were also studied.Based on the former laboratory results, VC suspension polymerization in the presence of hydrotalcite nano-particles surface modified with zinc stearate, were carried out in a 1001 industrial scale-up reactor. The influences of addition of hydrotalcite on the polymerization process and the structure of PVC resins were studied. It found that the feeding policy had great influence on the coating efficiency of hydrotalcite by PVC particles. The inversed feeding method was a better way to achieve the high coating of hydrotalcite by PVC resin. The addition of hydrotalcite had little effect on the particle features, and had no significant influence on the molecular weight of PVC. The whiteness, thermal stability time and thermal degradation temperature of PVC composite resin were significant increased as nano-hydrotalcite introduced into PVC. The heat-deformation temperatures of PVC products were also increased.The homogeneous dispersion of hydrotalcite particles in PVC in nanoscale was achieved as PVC/hydrotalcite composite resins were melt processed. Incorporating of hydrotalcite nanoparticles had significant influences on the mechanical properties of PVC, Young's modulus and tensile strength of PVC composites increased as hydrotalcite weight fraction increased. The maximum Charpy impact strength of PVC nanocomposite existed when the feeded amount of hydrotalcite was 1g/100g VC.ACR/SDS-HT composite was prepared by simultaneous in-situ polymerization and SDS-HT formation. SDS-HT was also prepared by co-precipitation method. The interaction of SDS with hydrotalcite layers and intercalation of partial ACR chains inhydrotalcite were confirmed. PVC/hydrotalcite nanocomposite with homogeneous dispersion, smaller dispersion size and partial exfoliation of hydrotalcite particles, were prepared by blending of PVC with ACR/SDS-HT, while, it was difficult to obtain the PVC/hydrotalcite nanocomposite by blending of PVC with SDS-HT. The fusion time of PVC decreased as the added amount of ACR.SDS-HT composite increased. The tensile modulus and strength of PVC composites increased as the added amount of ACR.SDS-HT composite increased. The maximum impact strength of PVC-ACR/SDS-HT was about 2 times of that of pure PVC.