Prediction of the radiation term in the thermal conductivity of crosslinked closed cell polyolefin foams

Abstract

The thermal conductivity and the cellular structure as well as the matrix polymer morphology of a collection of chemically crosslinked low-density closed cell polyolefin foams, manufactured by a high-pressure nitrogen gas solution process, have been studied. With the aid of a useful theoretical model, the relative contribution of each heat-transfer mechanism (conduction through the gas and solid phases and thermal radiation) has been evaluated. The thermal radiation can be calculated by using a theoretical model, which takes into account the dependence of this heat-transfer mechanism with cell size, foam thickness, chemical composition, and matrix polymer morphology. A simple equation, which can be used to predict the thermal conductivity of a given material, is presented.