A polymeric material is used in one part of a container for an eye-drop solution. The material is sterilized by ionizing radiation. The effect of exposure to different doses was studied by thermal analysis. The technique used is called oscillating DSC. The DSC signal can be separated into two components, reflecting reversible reactions and non-reversible reactions respectively. The sum of these two components makes up the conventional DSC signal. The conventional DSC signal showed no variation in the enthalpy for a melting reaction. However, the two components showed very clear changes, which could be correlated to dose. The most significant changes were found in the non-reversible component during heating of the samples.