Estimating the Thermal Conductivity of Polymeric Foams Based on a Theoretical Model Using Cell Size and Foam Density

Heat transfer of polymeric foams is consisting of three different mechanisms including heat transfer through a solid phase, gas phase, and thermal radiation. Thermal insulation properties of polymeric foams are affected by different structural properties. Also, these structural properties have a different influence on the different heat transfer’s mechanisms. Therefore, it is necessary to use theoretical models. Several theoretical models have been presented so far, meanwhile, providing theoretical models that can estimate the thermal conductivity using the easiest measurable properties along with sufficient accuracy and reliability can be very helpful. In this regard in the present study, a theoretical model based on cell size and foam density is developed in order to predict the thermal properties of polymeric foams. It was concluded that the error of the developed theoretical model is lower than 8% in comparison to the experimental results. In the following, the effect of most important structural parameters i.e. foam density and cell size on the thermal conductivity is investigated. Based on the results, determining the optimum density is necessary to achieve the lowest thermal conductivity. Also, the gas thermal conduction has the most contribution to the overall thermal conductivity and achieving the nanometer cell sizes can be useful in order to decrease it.