IMPROVING THE CELLULAR STRUCTURE AND THERMAL CONDUCTIVITY OF POLYSTYRENE FOAMS BY USING SEPIOLITE

摘要

Sepiolite particles with different surface treatments have been used as additives in polystyrene (PS) foams. In particular non-surface modified sepiolite, surface modified sepiolite using a quaternary ammonium salt and surface modified sepiolite using a silane have been produced for this particular purpose. Foams with densities in the range of commercial XPS (extruded PS) boards have been produced using the batch gas dissolution foaming technique with CO2 as blowing agent. The foams have been characterized both microscopically and macroscopically. The experimental results have shown that the particles used have a strong effect on cell nucleation, much higher than talc, (the typical nucleating agent used in XPS boards). The detected improvements in the cellular structure (lower cell size, higher cell density, lower open cell content and higher cell size homogeneity) have as a consequence a significant improvement of the thermal insulation and mechanical properties of the foams.