화학공학소재연구정보센터
International Polymer Processing, Vol.35, No.5, 503-517, 2020
A Comparison of CO2 and N-2 Foaming Behaviors of PP in a Visualization System
Understanding of polypropylene (PP) foaming is critically important to reduce the weight of automotive parts. In this study, we used a batch foaming simulation system with visualization cell, to observe the foaming behaviors of PP that is blown with CO2 and N-2 under various experimental conditions. We found that the nucleating agent content, initial temperature, pressure (i. e., gas content), and pressure drop rate during foaming have a significant effect on cell nucleation and cell growth. The cell density and the void fraction of PP foamed with CO2 and N-2, respectively, were separately observed and compared. It was found that under the same experimental conditions, the maximum cell density of PP foamed with CO2 was higher than that of PP foamed with N-2. However, the maximum cell density of PP foamed with CO2 was determined to be lower than that of PP foamed with N-2, when the same gas mole numbers were employed. Based on the experimental results, optimum foaming conditions and effective processing strategies jar PP-CO2 system are suggested.