Influence of Calcium Carbonate Fillers on the Properties of Recycled Poly(ε-caprolactone) Based Thermoplastic Polyurethane

In this work the effects of different crystallographic modifications of calcium carbonate (CaCO3) filler on the melt flow, mechanical properties, hydrolytic degradation, and shape memory behaviour of recycled low-temperature poly(epsilon-caprolactone)-based polyurethane (rTPU) were evaluated. Composites were prepared by two-roll milling varying filler content from 2 wt% to 6 wt %. It was found that at temperature range from 20 degrees C to 50 degrees C CaCO3 fillers do not change Young's modulus, they decrease tensile stress and deformation of rTPU, but improve its mechanical properties at elevated temperatures (up to 65 degrees C). rTPU melt flow index increases due to chain scission during the recycling and filler mixing with mill. Therefore, destruction temperature of rTPU is 20 degrees C lower than that of TPU. The CaCO3 does not change shape memory properties independently of filler type and transition from secondary shape to the primary shape at 70 degrees C temperature is completed within 17 s for both filled and unfilled rTPU. The investigation of hydrolytic degradation shows that CaCO3 only slightly increases degradation rate of rTPU.