MICROCELLULAR BIODEGRADABLE POLYMERIC FOAMS PRODUCED FROM SUPERCRITICAL FLUIDS AND NANOCOMPOSITE SOLUTIONS

摘要

In this study, polycaprolactone (PCL), a well known biodegradable polyester was used as matrix to obtain microcellular foams. CO{sub}2, in subcritical and supercritical condition, N{sub}2, and mixtures of CO{sub}2 and N{sub}2, were employed as blowing agents. Nanocomposites based on PCL and organically modified layered silicates were also prepared in order to investigate the effects of the clay content on the foaming process. A wide range of foam densities, cell density and dimension were obtained. Fine celled foams were produced both by using scCO{sub}2 and N{sub}2/CO{sub}2 mixture, with densities as low as 0.07 g/cm{sup}3. Microcellular foams were achieved by using the nanometric filler as nucleating agent. Sorption measurements were performed in order to investigate the solubilities and diffutivities of the different blowing agent at temperatures ranging from 70 to 90°C and up to 27MPa. These experiments allowed to correlate the different interaction between the polymer and the blowing agent to the final foam structure.