Effect of water on cellular structure and properties of rigid polyurethane-imide foams

PI prepolymerization method was adopted to synthesize rigid polyurethane-imide foams. The effect of content of water on the density, surface chalking degree and mechanical properties was analyzed. The relationship between the mechanical property and density was established following the power law. In addition, the cellular structure was observed using stereomicroscope and polarizing microscope. The results showed that, with the increased content of water, the density, compressive strength, compressive modulus, impact strength and cell edge thickness of rigid polyurethane-imide foams decreased, and average cell diameter and surface chalking degree of foams increased. The density exponent value was calculated as 1.78, 1.55 and 0.72 for compressive strength, compressive modulus and impact strength, respectively, for polyurethane-imide foams.