Effects of CaCO3 and Kaolin Filler Loadings on Curing Rates of Polyurethane Foams

Abstract

Commercial kaolin (Al2Si2O5(OH)4), a clay mineral obtained on the Upper Plateau (Jos, Central Nigeria) was characterized for physical properties such as moisture content (= 1.30%), sieved particle size (= 150μm) and (Apparent Bulk Density (= 0.40g/cm3) and compared to CaCO3, a rock mineral and a conventional filler presently used extensively in the foam industry in Nigeria, with moisture content (= 0.60%), sieved particle size (= 150μm) and (Apparent Bulk Density (= 0.75g/cm3). CPO and PPO foam formulations using conventional (CPO) and polymer (PPO) polyols with variations of kaolin and CaCO3 filler loading were investigated for curing rates. The results showed that curing decrease immediately after cream times for both fillers.The results also showed that the rate of curing is faster for kaolin filled foams than CaCO3 filled foams with the free isocyanate content exhibiting increases with filler loading indicating that fillers delay curing rates. However, this effect was observed to be more pronounced for CaCO3 filler than kaolin for the two types of polyols considered especially after aging for 720mins.This demonstrates that polymerization is usually incomplete because of the active isocyanate groups still present.