Two theoretical models that can be used to predict the thermal conductivity and Young's modulus of low-density polyethylene (LDPE) foams produced by a high-pressure nitrogen solution process are presented. The main factors that influence the properties of these materials were studied in terms of these models. The results show that the two properties depend on different factors. Moreover, the matrix polymer morphology of the foams was studied and compared to that of the solid sheet from which the foams were manufactured.