Effect of supercritical CO2 and N2 on the crystallization of linear and branched propylene resins filled with foaming additives

The thermal behaviors of linear and branched propylene materials with foaming additives were investigated using a high-pressure differential scanning calorimeter (DSC). In this study, the effects of material branching, dispersed additives, and dissolved blowing agent on the crystallization temperature of propylene materials were elucidated. It was observed that branching promoted the crystallization kinetics of propylene materials significantly. However the increased crystallization temperature of branched propylene materials was lowered under high pressure of gas. The effect of hydraulic pressure was determined by performing high-pressure experiments with helium which has a very low solubility in polymers. The effects of foaming additives such as talc and GMS as well as the effect of cooling rate on the crystallization temperature were also studied. The experimental results indicate that the crystallization temperature could be increased as much as 30 degreesC by branching the propylene resin and/or adding an additive in the propylene resin.