Surface modification of CaCO filler and its characterization using inverse gas chromatography (IGC)

Abstract

A CaCO₃ filler was treated by generally used coupling agents and a special one - ethylene-octene copolymer (POE)-g-maleic anhydride (MAH). Fourier transform infrared spectroscopy (FTIR) results show that the special coupling agent POE-g-MAH, in a chemical reaction with CaCO_3, can produce an interfacial layer stronger than simple physical adhesion attained with usual coupling agents. Inverse gas chromatography (IGC) was used to investigate the surface free energy of CaCO₃ after surface modification and to optimize the monolayer content of coupling agents. Based on the IGC results, it can be deduced that the monolayer cover is around 1.9% for CaCO₃ treated with a titanate coupling agent. Scanning electron microscope (SEM) observation results show that the separated morphology existed in the ternary composites containing CaCO₃ after surface treatment with coupling agents, whereas the core-shell morphology was obtained in the ternary composites with POE-g-MAH. The encapsulation of the CaCO₃ filler treated with POE-g-MAH was caused by the strong chemical reaction between the elastomer and CaCO₃ particles.

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