Understanding of phase transformations that occur in the polymer as a result of temperature changes is extremely important in the context of planning and designing the processing of polymeric materials. The effect of HAp powder addition on the thermal properties of the PBS-DLS copolymer was investigated using the DSC technique. In addition to understanding the nature of the materials produced, the purpose of the calorimetric studies was to compare the effect of the addition of nHAp and µHAp fillers on the thermal properties of the copolymer. Figure shows the second heating DSC thermograms of the materials tested, while Figure shows the first cooling thermograms. The parameters obtained from these data are summarised in Table .