Investigation On Synthesis And Application Of Calcium Carbonate Modifier

Calcium carbonate is widely used as an important functional inorganic filler in many industrial fields, such as plastic, rubber, coatings and papermaking. However, the calcium carbonate aggregates easily and the interface interaction between calcium carbonate and matrix is weakened due to its hydrophilicity. So the mechanical properties of composite materials are decreased. The surface modification can solve the problem effectively and there have been various kinds of agents used in the modification of calcium carbonate. But, in practice, these agents still have some limitations. In order to meet the needs of industrial applications, the eleostearic acid anhydride hydrolyzate and acrylic acid-butyl acrylate coplymer with multi-functional groups were synthesized based on molecular design.A novel modifier of eleostearic acid anhydride hydrolyzate was synthesized through Diels-Alder reaction using eleostearic acid and maleic anhydride as raw materials. The main influencing factors of the reactions were studied and the optimal reaction conditions were determined. The effects of surface modification were valued by means of activation grade, oil-absorption value, system viscosity and contact angle. The results indicated that the particles had valid surface coating, effectual compatibility and excellent dispersion with organic substance. Compared with the conventional modifiers, this modification process had the advantages of environment friendly, lower energy consumption and cost, simple operation.Through radical copolymerization, a series of acrylic acid-butyl acrylate copolymers were synthesized by acrylic acid and butyl acrylate. The influence of neutralized and unneutralized modifiers with different molecular weights was investigated. Surface characteristics of modification were valued by means of sedimentation volume, oil-absorption value, system viscosity and contact angle, which testified that the modifier with low molecular weight had better improved effect than that with high molecular weight and the neutralized process has better active effect.The composites of modified CaCO3/PVC were prepared by the PVC matrix and two kinds of modified calcium carbonate respectively. The impact strength and the breaking elongation of composites filled with modified calcium carbonate were increased remarkably in comparison with those of unmodified calcium carbonate, calcium carbonate modified by stearic acid and activated precipitated calcium carbonate. The modified calcium carbonate improved the toughness of composites specially. The scanning electron microscope and thermogravimetry analysis showed that the two kinds of modifiers can be firmly bonded on the surface of calcium carbonate and there was a strong interface adhersion between modified calcium carbonate and resin matrix.