Thermal Conductivity of Low-Density Polyethylene Foams Part II: Deep Investigation using Response Surface Methodology

Here, we conducted a deep study on the thermal insulation performance of polymeric foams using response surface methodology (RSM). Cell size, foam density, and cell wall thickness were considered as variable parameters. Analysis of variance (ANOVA) tool was utilized to recognize the effective parameters on the different mechanisms of heat transfer. Regression models were presented to forecast the different mechanisms of heat transfer and their validities were checked using ANOVA tool as well as compared to the thermal conductivity results. Surface plots were used to study the interaction effect of significant parameters. The optimization procedure was performed using RSM. Foam density and cell wall thickness are effective parameters on the solid thermal conductivity whereas cell size and foam density were significant parameters on the thermal radiation. By decreasing foam density, gaseous thermal conductivity and thermal radiation were increased and solid thermal conductivity was reduced. The regression model predicted the overall thermal conductivity with an average error smaller than 3%. The results illuminated that the overall thermal conductivity in the optimum conditions was as small as 29 mW/mK.