Nanostructured modification of mineral particle surfaces in Ca(OH) 2–H 2O–CO 2 system

Abstract

Traditionally pulverized particulates of raw minerals, such as ground calcium carbonate (GCC), wollastonite and dolomite, are usually of smooth/flat surface and pointed edges angles which have disadvantageous effects on the mechanical properties of composite polymer materials filled with the powders. On the other hand, dispersion of nanoscaled calcuim carbonate powders can not be easily achieved when filled in organic polymer, because of their huge specific surface energy and intense/strong conglomeration. Aiming at utilizing the advantages of both traditionally pulverized particles and nanosized ones and overcoming their disadvantages, a wet-coating method is developed and three kinds of raw-mineral-based composite powders have been successfully prepared by chemical precipitation in Ca(OH) 2–H 2O–CO 2 system on the pulverized particles in our group. It is shown that the composite powders of traditionally pulverized particles coated by nanosized calcium carbonate particles of 20–100 nm are of rough surface, blunt edges, larger specific surface area, compared with the uncoated powders. Some technological parameters are mainly analyzed for the coating process in the paper. Blending the coated powders to polypropylene demonstrates significant improvement in filling properties to the uncoated ones.