The Effects of Foaming Conditions on Plasticized Polyvinyl Chloride Foam Morphology by using Supercritical Carbon Dioxide

Abstract

This research studies the effects of foaming conditions by using supercritical (scCO2) as a physical blowing agent on plasticized polyvinyl chloride (PVC) foam morphology. Foaming conditions were foaming temperature of 40, 60, and 80 oC, foaming pressure of 120, 150, and 170 bar at constant soaking time of 30 min. Depressurization was employed to activate nucleation and samples were cooled at room temperature about 30 oC for stabilization, which cause shrinkage behavior. PVC foam samples were calculated percentage of shrinkage (Sh) by using density at before and after aging process at 30 oC for 12 h to make sure for completely permeation of air into foam structure. PVC foam by using scCO2 as a physical blowing agent reveal uniform closed bubble and regular foam structure with thin bubble wall (less than 5 μm). At high solubility of scCO2, PVC foam samples contain bubble diameter with less than 20 μm and high bubble density within the range of 108 - 1011 bubbles/cm3. PVC foam samples at low solubility foaming conditions display a large bubble diameter (more than 140 μm) and lower bubble density (106 bubbles/cm3). These foam samples are be able to reduce the density about 75% when compared with unfoamed sample but it structure highly shrink with Sh more than 50%.