Effect of Processing Parameters and Vibrating Field on Poly(Vinyl Chloride) Microcellular Foam Morphology

The effects of processing parameters such as processing pressure, temperature, mixing time and rotor speed on polyvinyl chloride foams were investigated by using a novel microcellular foaming setup. The experimental results show that a proper temperature and a high pressure can promote CO2 dissolving in polymer, which makes cell density increase and cell size decrease. Increasing mixing time and rotor speed also promote CO2 dissolving in PVC and speed up forming single-phase polymer/CO2 solution. The effects of oscillatory shear on polyvinyl chloride cell morphology were also studied. The combined shear improves the mixing, and thus shortens the time needed for homogeneous polymer/supercritical CO2 solution formation. Foamed samples with the cell density of 1.0 × 107–3.5 × 108 cells/cm3, average cell size of 15–60 µm and bulk density of 0.6–0.87 g/cm3 had been produced.