Surface Modification Research Of Synthetic Mica

Synthetic mica, a kind of layer silicate compounds, has been widely used in plastic, rubber and coatings industries because of their electrical insulation, high temperature resistance, chemical stability, stretch and bend resistance and ultraviolet-proof properties. Synthetic mica may have poor compatibility with organic based resin from plastic, rubber or coatings when added into them. Therefore, it is very necessary to modify synthetic mica for further use.In this paper, synthetic mica was modified via synchronously dried and roasted method by using hexadecyltrimethoxysilane(C16SCA) as modified agent and NH4HCO3 as additive agent. It was found that prepared synthetic mica possessed good hydrophobic performance(water contact angle is 125.1°) and can be dispersed well in n-hexane for several hours through the treatment process of 20 wt.% N content from NH4HCO3, 5 wt.% C16 SCA and drying and roasting at 120℃ for 3 h. Prepared synthetic mica was characterized by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and thermogravimetric(TG) for discussing mechanism of surface modification. Results showed that hydroxyl group on the surface of synthetic mica particles formed by the volatilization of NH3 during drying and roasting process can react with another hydroxyl group from C16 SCA around synthetic mica particles by the way of loss of H2 O, and thus long carbon chain of C16 SCA linked onto the surface of synthetic mica particles by means of the formation of Si-O-Si groups.For the purpose of simplification of modification process and choosing cheaper modified agent, synthetic mica was prepared by adopting poly-methyl hydrosiloxane(PMHS) as modified agent via synchronously dried and roasted method. It was found that prepared synthetic mica possessed good hydrophobic performance(water contact angle is 119.5°) and can be dispersed in n-hexane through the treatment process of 20 wt.% N content from NH3H2 O, 10 wt.% PMHS and drying and roasting at 160℃ for 3 h. Prepared synthetic mica was characterized by FTIR, XPS and TG for discussing mechanism of surface modification. Results showed that hydroxyl group on the surface of synthetic mica particles formed by the volatilization of NH3 during drying and roasting process can react with another hydroxyl group or Si-H group from PMHS around synthetic mica particles by the way of loss of H2 O, and thus PMHS linked onto the surface of synthetic mica particles by means of the formation of Si-O-Si groups.