Clay-based heat insulator composites: Thermal and water retention properties

The formulation of unsaturated polyester composite as an insulating material that gives the best in terms of thermal and water retention properties was investigated as a function of filler type and content. Different types of local fillers were used in the formulations. Bentonite-based unsaturated polyester composite which is denoted as BBUPEC was found to have stable and compatible thermal, physical, and chemical properties. BBUPEC thermal conductivity, k, values lie between 0.1 and 0.2 W/(m K). It was found that at 50 wt.% filler content and 40 wt.% polyester content, k of BBUPEC is minimum. Calcium carbonate-based composite also gave a similar value. However, in terms of citric acid impregnation, calcium carbonate-based composite was not stable and dissolution took place. In terms of water retention value, citric acid and NaOH impregnation values, one could say that bentonite-3-based composite was the best among BBUPEC. Consequently, one would say that BBUPEC shows good characteristics in terms of thermal conductivity and physical and chemical stability and with such inexpensive and abundant fillers from natural resources, they pose a potential thermal insulating material. Sandwiching of BBUPEC in wall structures by one-third of the total thickness will significantly reduce the overall heat transfer coefficient in home and industrial applications by at least 50%.