Effect of gas type on microcellular foam process using atmospheric gases as a blowing agent

摘要

This work concerns the effects of gas type on the microcellular foam process when using atmospheric gases as a blowing agent. Three gases were investigated, CO_2, N_2 and argon. Gas absorption, viscosity reduction and cell formation were tested with these gases using the foaming process simulator (2) and an extruder with a capillary die. Significant differences were observed among these gases. The gas absorption of N_2 and argon in polymers was much lower than CO_2. TShe diffusion rate also seems to be lower with N_2 and argon. The viscosity reduction was also lower with N_2 and argon. Cell nucleation density was similar for all the three gases at high saturatioin pressures, but it was significantly lower with N_2 or argon when the saturation pressure is low. The cell size is smaller with N_2 and argon at a hgh saturation pressure, especially with N_2. As a results, the foam density is higher with these two gases at the same foaming conditions compared to CO_2.