Microwave exfoliation of vermiculite and phlogopite

Vermiculites and phlogopites can be exfoliated by chemical and thermal treatment methods to obtain chemically inert, adsorbent, fire-resistant, low-density materials with excellent thermal and acoustic insulation properties. The water content of the clay generally determines the extent of exfoliation and the presence of interstratification is claimed to increase the rate of exfoliation. Considering the strong interaction between water and microwaves, the effect of microwave power on exfoliation characteristics of vermiculites and phlogopites after treatment with water and hydrogen peroxide solution were studied at 600, 950 and 1300 W for microwave exposure times of 10, 20, 30, 60, 120 and 300 s. It was observed that the water molecules in the interlayers of the individual flakes were driven off quickly by microwave treatment causing layer separation in the samples. The vermiculite sample showed 2.8 and 5.6 times, respectively, the exfoliation ratio of the phlogopite samples, in accord with their water contents.