The cold chain currently uses aqueous polymer solutions as phase-change material (PCM), which permits it to thaw more slowly than ice. The aim of this work is to study some physical properties of such PCM and to propose an experimental protocol allowing us to compare different PCMs under specific heat transfer conditions. Length of the phase change flat plate during thawing is proposed to compare different PCMs. Investigations on the rheological behavior are also presented. Analysis of the results makes it possible to show that kinetic of phase change is related to the rheological properties of material. The thermal properties thus should not constitute the only physical criterion for the choice of a material.