Thermal and Mechanical Characterization of Polymeric Foams with Controlled Porosity Using Hollow Thermoplastic Spheres.

Polyurethane (PU) foams with controlled porosity and pore structure are prepared via judicious study on expanding process parameters for thermoplastic expandable microspheres which are compatible with PU synthetic process. Thermal and mechanical properties of PU foams are found to be generally governed by amount of the porosity. Thermal conductivity of PU foams with controlled porosity is measured at 30 °C with transient hot bridge method. The measured thermal conductivity of PU foams is estimated using theoretical models, proving the formation of spherical pore structures of expandable microspheres in PU matrix and serving as an internal porous material.