Surface Modification Of Calcium Carbonate And Its Application In PVC

Polymer/CaCO₃ composite particles were synthesized by grafting polymerization. The CaCO₃ was firstly treated with modifiers(OA, UA,MAA) which have unsaturated bond, followed by radical grafting of vinyl monomers(MMA, St,VCM) through micro-suspension polymerization or emulsion polymerization. The morphology of the composite particles were characterized with the aid of TEM,FT-IR and TG. The experimental results show that all the modifiers can bond to and align on the particle surface, which led to the formation of carboxylate salts. The polymers produced were found to cover the CaCO₃ particles well, some polymer chains were grafted onto the surface of CaCO₃ particles through the unsaturated bond of modifiers.PVC-matrix composites were prepared by blended PMMA/CaCO₃ and PVC/CaCO₃ composite particles with PVC, respectively. The influence of the effecting factors of the synthesized Polymer/CaCO₃ composite particles on the mechanical properties of PVC-matrix composites was investigated in detail. Morphological structure of PVC-matrix composites revealed that the Polymer-coated CaCO₃ improved the dispersion of the fillers in the PVC matrix, and enhanced the interfacial adhesion between the CaCO₃ particles and PVC. With increasing content of the fillers, the notched impact strength and the tensile strength of PVC-matrix composites improved simultaneously. When the filler loads were high, the tensile strengths became lower than that of pure PVC. In the case of PMMA/CaCO₃ composite particle as fillers, the impact strength of PVC-matrix composites can increase to 24.52 kJ/m².CaCO₃/PBA/PMMA and CaCO₃/PBA/P(MMA-St) composite particles were prepared by seeded emulsion polymerization. And PVC-matrix composites were obtained by blending method. The impact strength of the composite was improved remarkably with the addition of PBA. The impact strength increased above 4 times that of PVC, when the ratio of BA/(MMA+St) was 60/40, CaCO₃/nonomers ratio was 30/100, St/MMA ratio was 40/60, CaCO₃/PBA/P(MMA-St) content was 8wt%.The tensile behavior, impact strength and Vicat temperature of PVC blends (PVC/ACR/CaCO3) were investigated. The results showed that the CaCO3-OA-PVC toughen the blends significantly when the ACR content reached a certain value. The Vicat temperature and tensile strength of the blends were also increased.