Orthogonal Design Study on Factors Affecting Foaming Behaviors of Polypropylene and Polypropylene/Nano-Calcium Carbonate Nanocomposites

Abstract

A new process was used to foam polypropylene (PP) and its nanocomposites with supercritical carbon dioxide (SC-CO₂) as the foaming agent. Orthogonal designs were carried out for the first time to optimize experimental conditions and investigate the interactions among the foaming temperature, saturation pressure, m infiltration temperature and foaming time. Results showed that the foaming temperature and saturation pressure had the most important impact on the cell diameter and expansion ratio, respectively. The optimal experimental conditions of PP and nanocomposites were different. The cell density was more relative to the cell diameter comparing with the expansion ratio. The results of analysis of variance indicated that only foaming temperature influenced the cell diameter of PP significantly, there were almost no interactions among those factors.

Keywords:

• Foams
• Nanocomposites
• Orthogonal design
• Polypropylene
• Supercritical carbon dioxide

Notes

PP is the PP without impregnation, PP40, PP80 and PP120 is the PP impregnated at 40, 80 and 120°C, respectively.

“***” represents that the factor influences the experimental results highly significantly; “**” represents that factor influences the experimental results significantly; “*” represents that factor influences the experimental results slightly; “—”represents that factor have no influence on the experimental results.