Study On Preparation And Application Of Polyacrylate/Nano-CaCO₃ To Modify Poly (Vinyl Chloride) Nanocomposites

To improve the dispersion and compatibility of nano-CaCO3, mechanical properties and structure of poly(vinyl chloride) (PVC) nanocomposites, polyacrylate/nano-CaCO3(PA-C) composite particles were successfully prepared. The application of PA-C composite particles to toughen Poly(vinyl chloride) nanocomposites was researched in this thesis.In chapter 2, the polyacrylate was prepared by the emulsion polymerization. The effects of initiator, temperature, ratio of monomers on the performances of the polymer were investigated. In chapter 3, the polyacrylate resins with high molecular weight and suitable structure were coated on nano-CaCO3 particles to prepare the polyacrylate/nano-CaCO3(PA-C). Properties of PA-C were characterized by TEM, Thermogravimetic analysis (TGA), FTIR, particle-size distribution, BET, DBP, Absorption and sedimentation volume, etc. The effects of PA-C composite particles on the mechanical properties and morphology of PVC nanocomposites were investigated in chapter 4.The result show the molecular of polyacrylate reaches 2.0×105～2.0×106 and the glass transition temperature can be controlled. With the polyacrylate coated on the surface of nano-CaCO3 particles by chemical bonds and physical adsorption, nano-CaCO3 particles got changed from hydrophile to hydrophobe. The presence of PA-C composite particles led to a slight decrease in the tensile strength but sharp increase in fracture toughness. With polyacrylate content of 10%, the impact strength got a maximum of 57kJ/m2. The flexure modulus also increased with increasing the composite particles concentration. Morphology observation by TEM showed that PA-C composite particles were dispersed in PVC matrix uniformly and the surface of nano-CaCO3 particles was covered by polyacrylate shell which enhanced interactions with PVC matrix. The fractography of PVC by SEM revealed that the polyacrylate interlayer could effectively induce deformation of the matrix around the nanoparticles to increase energy absorptions for crack initiation and propagation.