INTERPENETRATING POLYMER NETWORKS AS ENERGY-ABSORBING MATERIALS

Polyurethane-poly(vinyl chloride) pseudo-IPN (interpenetrating polymer network) elastomers, polyurethane-poly(vinyl ester) IPN foams, and polyurethane-epoxy-unsaturated polyester two- and three-component IPN foams and elastomers were studied by dynamic mechanical spectroscopy sound absorption (impedance tube technique), compressive hysteresis, resilience (ball rebound), and other measurements. The IPN systems were tailored to possess broad glass-transition temperatures, and the effects of this broad viscoelastic region on the energy-absorbing properties were determined. Materials with broad transitions resulted in enhanced mechanical-energy-absorbing properties, but not always improved absorption of airborne noise. The results suggest that sound attenuation can be more a function of cell morphology rather than polymer morphology.