Surface Modification And Properties Of Pyrophyllite

Deposits of pyrophyllite in Zhejiang account for 52% in the whole country. As reinforcing materials for polymers, it is expected to endow them new function because of exceptional physical and chemical properties. However, pyrophyllite is not easily dispersed in polymers due to its high polarity, it need to be organically modified to produce polymer-compatible powder.In this study, mechanochemical treatment was used for pyrophyllite modification with silane coupling agents（KH550、KH570、A-151）and titanate coupling agent（KHT201） respectively. Influences of factors such as concentration of coupling agents、pH value and time of modification were studied in this experiment. Then, the hydrophobicity of pyrophyllite were enhanced by KH570, A-151 and KHT-201, except KH550. According to wettability, it was found that the titanate coupling agent KHT-201 is the best modifier for pyrophyllite. When the titanate coupling agent is 0.5wt%, after 45min modified, the activation coefficient enhanced to 0.991 from 0.076, contact angle increased to 115.33°from 0°and viscosity reduced to 205mPa·s from 390mPa·s. The mechanical performance of PVC composite was higher than raw pyrophyllite, and could be compared with commer filler CaCO₃. What’s more, calcination-pickling pyrophyllite was modified with mechanochemical treatment in this paper either, then the optimal technological condition was obtained.We used orthogonal experiment to confirm the optimal condition of stearic acid modification: the concentration of modifier is 1.25%, concentration of slurry is 7.5%, the modification temperature is 30℃, and the modification time is 30min. Through the FT-IR curves of the modified pyrophyllite, new bonds were produced between the modifier and pyrophyllite, and the mechanical performance of PVC composite confirmed the modified calcination-pickling pyrophyllite was polymer-compatible filler.