Nanoclay‐Modified Rigid Polyurethane Foam

Abstract

Montmorillonite‐based organoclay was incorporated into rigid polyurethane foams. Clay was dispersed first in the isocyanate component ultrasonically. The dispersion was investigated using small angle X‐ray scattering and rheology. It was found that using toluene as common solvent enhanced dispersion significantly. The addition of 1 wt% clay resulted in reduced cell size from 0.40 to 0.28 mm and increased cell number density on 300‐index foams. Gas chromatography showed that diffusion of blowing agent out of the closed cells of the foam decreased by more than 82% with clay loading. The reduction in permeability is caused by the combined effect of smaller cell size and dispersed nanoclay acting as diffusion barrier. At 1% clay no mechanical strength improvements were observed. Higher levels of clay loading caused significant viscosity increase and a yield stress that made mixing the reactive components difficult.