MMT‐St and PLA synergistically enhanced the microcellular of TPU foam and improved its dimensional stability

Abstract

Thermoplastic polyurethane elastomer (TPU) is a commonly used material for foam preparation. However, its application is hindered by significant shrinkage behavior. To reduce the foam shrinkage, polylactic acid (PLA) and calcium stearate‐modified montmorillonite (MMT‐St) were incorporated into the polyurethane matrix. The TPU/PLA/MMT‐St composite foams were formed using an intermittent supercritical carbon dioxide (scCO2) foaming process. The addition of PLA inhibited the relaxation of TPU chain segments, while the introduction of calcium stearate (GaSt2) improved the dispersion of MMT within the matrix, increased the nucleation sites of cell growth, and improved cell structure. The cell diameter decreased from 10 to 4 μm, while the cell density increased from 4.1×1012 to 15.8×1012 cell/cm3. In addition, the cell distribution range narrowed from 4‐19 to 2‐6 μm. Incorporating MMT‐St increased the crystallinity and thermal stability of TPU/PLA, mitigated chain relaxation at room temperature, and enhanced foam dimensional stability. As a result, this led to a decrease in shrinkage rate from 27.5 to 5%. As both matrices of the material are thermoplastic, this composite foam possesses recyclability with enhanced material utilization.This article is protected by copyright. All rights reserved.