Bubble growth in the microcellular foaming of CO₂/polypropylene solutions

Abstract

This article is concerned with bubble growth dynamics in the CO 2 /polypropylene microcellular foaming process. The effect of the melt strength on the bubble growth was thoroughly investigated in theory for the first time. The theoretical results indicate that enhanced melt strength effectively restrains the bubble growth and stabilizes the bubble oscillation. Higher melt strength leads to lower bubble growth rate, shorter growth time, and smaller ultimate bubble size. Compared to the melt strength, the viscoelasticity and the gas pressure have less effect on the microcellular foaming process. The bubble growth varies a little as the viscoelasticity is varied. The bubble oscillation and growth rate are enhanced with increasing gas pressure, which leads to the augmentation of the bubble size.

Preparation of low density amorphous poly(aryletherketone) foams and the study of influence factors of the cell morphology

“…Studies 22,23 indicated that cells nucleate and grow in a quite short time at the start of the foaming process. According to time-temperature equivalence principle, the elasticity may increase with increasing gel content at temperatures above T g in the dynamic process, although the modulus seems to be no difference for the samples as shown in Fig.…”

Influence of the Injection‐Molding Parameters on the Cellular Structure and Thermo‐Mechanical Properties of Ethylene‐Propylene Block Copolymer Foams

“…Most of the previous experimental3–7 and theoretical8 studies on PP foaming had been performed with CO 2 and basically using a batch process. From all of these studies, several conclusions may be useful to the present study.…”

Elastomeric foam prepared by supercritical carbon dioxide

“…Melt strength or/viscoelasticity (elongational viscosity) is one of the most important properties to evaluate foam materials. Lower melting strength could cause cell rupture and non‐uniform cell structure in the process of foaming . Elastomer generally has much higher viscoelasticity than that of plastics, which results in uniform cell structure.…”