Nano-sized CaCO3 was synthesized by

Nano-sized CaCO3 was synthesized by in situ deposition technique. UPR/CaCO3 nanocomposites were preparedat various filler contents by casting method. NanoCaCO3 was well dispersed in the UPR matrix, when the nano-CaCO3 content was below 5 wt% and few agglomerations of particle were found at above 5 wt% loading of nano-CaCO3 in UPR matrix. The tensile, flexural, and impact strengths of UPR/CaCO3 nanocomposites were increased to a maximum, when nanoCaCO3 content was 5 wt% and decreased with further addition of nano-CaCO3 content. Flexural modulus of nanocomposites increased linearly with increasing nano-CaCO3 content in UPR matrix. The fracture surface of impact test samples was also examined through SEM. It was observed that the brittle fracture of UPR is converted into ductile fracture with the addition of CaCO3. The DMA result also showed that optimal storage modulus and glass transition temperature (Tg) were obtained at a nano-CaCO3 content of 5 wt%.