Mechanical, Morphological and Thermal Properties of Rigid Polyurethane Foam: Effect of the Fillers

Abstract

Rigid polyurethane foam (PUF) having different fillers such as precipitated silica (SiO2), precipitated calcium carbonate (CaCO3) and glass powder (GP) were prepared by blowing with distilled water. The effect of filler loading on different properties of PUF was studied. In this investigation, the filler content was varied from 5 to 50 parts per hundred of polyol (phr) by weight. The properties such as density, mechanical, morphological, water absorption, thermal conductivity and thermal properties of the filled PUF were compared with the neat PUF. The density of silica filled PUF decreases with an increase in the filler loading. In case of calcium carbonate and glass powder the density initially decreases with filler loading, but after a certain concentration of fillers there is an increase in density with filler content. The mechanical properties such as compressive stress at 10% strain, compressive modulus and hardness of the filled PUF decrease in comparison with the neat PUF, due to the reaction between isocyanate and surface functional group present in filler. In all cases, the water absorption of the PUF increases with the increase in filler loading, due to the decrease in the closed cell content. The thermal conductivity analysis of PUF shows that the insulation properties decrease with the increase in silica as well as CaCO3 loading. This is mainly due to formation of open and damaged cell structure. However, when glass powder is used as filler the thermal conductivity first decreases, but later increases with filler loading.