Depressurization induced morphology control in solid-state microcellular batch foaming process

Abstract

This research article describes the impact of the depressurization rate change on the morphology of microcellular polycarbonate foams (PCMFs) using batch-wise foaming with carbon dioxide as a physical blowing agent. It was expected that the depressurization rate will affect the foaming behavior of microcellular foamed polycarbonate (PCMFs). While keeping other variables constant and changing depressurization rate, the depressurization rate affects the cell size, cell density, cell size distribution, and expansion ratio. The result showed cell diameter 5 ± 0.5, 7 ± 0.8, 9 ± 1.2, and 9.5 ± 1.5 µm and expansion ratio 5.2, 5.5, 6.0, and 6.3 at depressurization rate of 0.5 (D1), 0.05 (D2), 0.01 (D3), and 0.005 (D4) MPa/Sec, respectively. The cell area distribution showed that a higher depressurization rate leads to the more regular distribution of cells. The cell densities were observed as 2.6 × 1010, 4.6 × 109, 2 × 109, and 8.2 × 108 cells/cm3 at D1, D2, D3, and D4. It is investigated that as compare to depressurization rate other variables such as saturation pressure, foaming temperature and foaming time has more impact on properties of PCMFs.