Surface modification of sericite and preparation of sericite/polystyrene with enhanced thermal-insulating performance

Since sericite has no ion exchange capacity and no expandability in water, it can hardly be intercalated, which substantially degrades the thermal-insolating performance of sericite/polystyrene composite materials. In this paper, the surface modification technique of sericite was optimized. Moreover, the coupling agent and sericite were dissolved in a polar organic solvent for the first time, so that they can fully react in the organic solvent, which significantly increase the cation exchange capabilities of sericite. After surface modification, the sericite exhibits layered morphology, and the coupling agent spots can be clearly observed on the surface. The contact angle of the modified sericite increases from 0 degrees to 90 degrees, thus ensuring the hydrophobic effect. Therefore, the expandable polystyrene (EPS) with uniform particles can be prepared by adding the modified sericite into the styrene suspension polymerization, which guarantees a 15% reduction in thermal conductivity of EPS. Our investigation on the surface modification of sericite is expected to shed more light on the fabrication of clay/polymer composite system, and the EPS may potentially be applied as an ideal thermal insulation material.