Preparation of poly(propylene carbonate)/nano calcium carbonate composites and their supercritical carbon dioxide foaming behavior

ABSTRACT Biodegradable polymer foams are attracting extensive attention in both academic and industrial fields. In this study, an emerging biodegradable polymer, poly(propylene carbonate) (PPC), was compounded with nano calcium carbonate (nano‐CaCO3) and foamed via supercritical carbon dioxide for the first time. Four concentrations of nano‐CaCO3, 1, 3, 5, and 10 wt %, were used and the thermal properties of PPC/nano‐CaCO3 composites were investigated. The glass‐transition temperature and thermal decomposition temperature of the PPC/nano‐CaCO3 composites increased with the addition of nano‐CaCO3. The morphologies of the PPC/nano‐CaCO3 composites and the rheological results showed that homogeneous dispersions of nano‐CaCO3 and percolated nano‐CaCO3 networks were achieved at a nano‐CaCO3 content of 3 wt %. Therefore, the finest cell diameter (3.13 μm) and highest cell density (6.02 × 109 cells/cm3) were obtained at the same nano‐CaCO3 content. The cell structure dependences of PPC and PPC with a nano‐CaCO3 content of 3 wt % (PPC‐3) foams on the foaming pressure and temperature were investigated as well. The results suggested that the cell structure of PPC‐3 was more stable at different foaming conditions due to the networks of nano‐CaCO3. Moreover, the change in pressure was more influential on the cell structure than the temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42248.