Solid-State Microcellular Polycarbonate Foams. II. The Effect of Cell Size on Tensile Properties

The effect of cell size on the tensile behavior of high-relative-density microcellular polycarbonate foams is investigated. Microcellular PC foams were produced in a way that allowed the average cell size to be varied, while the foam density was held constant. The polycarbonate-CO(2) system offers an order of magnitude variation in the average cell size at a given density, allowing the tensile properties of microcellular polycarbonate to be investigated as a function of cell size. It was found that the tensile modulus, tensile strength, elongation to break, and toughness are not significantly affected when the average cell size is varied from 2.8 to 37.1 mu m, and the nominal relative density is held constant at 0.5. This result is significant for solid-state processing of microcellular polycarbonate foams of the type produced here, for it shows that regardless of the processing conditions and regardless of the average cell size, if two foams have the same density then they will also have the same tensile properties. POLYM. ENG. SCI., 50:2170-2175, 2010. (C) 2010 Society of Plastics Engineers