Influence of Chain Extender on The Thermal, Rheological, and Supercritical Foaming Behavior of Polyamide‐12

Abstract

In this study, the influence of chain extender (CE) concentration on the batch foaming behavior of Polyamide 12 (PA 12) under supercritical CO2 batch foaming is investigated. Foam density and expansion behavior were analyzed as a function of processing temperature and pressure. Significant improvements in foam structure and density were observed with increasing CE content. This led to fine and uniform morphologies, accompanied by a substantial increase in cell density. Optimal performance was achieved at 0.5 wt.% CE, where the smallest cell size and the highest nucleation density were obtained, along with low foam densities in the range of approximately 0.06 to 0.09 g/cm3. Rheological analysis revealed that CE incorporation significantly increased melt viscosity, elasticity, and strain‐hardening behavior, enhancing melt stability during cell growth. DSC analysis indicated a reduction in crystallinity and the formation of heterogeneous crystalline structures, with crystallization temperatures shifting to higher values, and a broader melting behavior was observed. These findings provide critical insight into the role of modification and processing conditions play in the effect of foam structure and performance, offering a naive strategy for of PA 12 batch foaming.