Fluoroelastomer-Induced Microcellular Structure in Polyolefin Elastomer Foams: a Pathway to Reduced Shrinkage and Enhanced Mechanical Properties

Abstract

Polyolefin elastomer (POE) is widely used in automotive components, footwear materials, and other applications due to its excellent elasticity and thermoplastic processability. However, POE foams prepared via supercritical carbon dioxide (scCO₂) foaming often face significant shrinkage issues, severely limiting their practical applications. Enhancing the rigidity of cell walls through irreversible chemical crosslinking is the prevailing strategy for suppressing shrinkage. However, this compromises recyclability. Balancing anti-shrinkage, high foaming ratio and recyclability remains a critical challenge. In this study, we propose a novel approach to fabricate POE/FKM (fluoroelastomer) foams with high open-cell content by introducing FKM as a modifier. The results show that with 10 wt % FKM, the foams attain an open-cell content of 95.1% and a foaming ratio of 27.5 times, while the shrinkage ratio is significantly reduced from 64.6% (for pure POE foams) to 12.1%. These performance improvements are attributed to the high CO₂ affinity and heterogeneous nucleation effect of FKM, which promote the uniform cell refinement and the formation of a highly open-cell structure. This structure effectively reduces the negative pressure within the cells, thereby improving dimensional stability. This study proposes a high-performance POE/FKM foam, offering a feasible approach for developing polyolefin foams with excellent anti-shrinkage properties, recyclability, and outstanding mechanical performance.