Affiliation:
1. College of Chemistry and Chemical Engineering Shaanxi Key Laboratory of Chemical Additives for Industry Shaanxi University of Science and Technology Xi'an Shaanxi 710021 P. R. China
2. China Leather and Shoe Industry Research Institute (Jinjiang) Co., Ltd. Jinjiang 362200 Fujian China
3. College of Bioresources Chemical and Materials Engineering Xi'an Key Laboratory of Green Chemicals and Functional Materials Shaanxi University of Science and Technology Xi'an Shaanxi 710021 P. R. China
Abstract
Thermoplastic polyurethane (TPU) elastomer 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) are incorporated into the polyurethane matrix. The TPU/PLA/MMT‐St composite foams are formed using an intermittent supercritical carbon‐dioxide‐foaming process. The addition of PLA inhibits the relaxation of TPU chain segments, while the introduction of calcium stearate (GaSt2) improves the dispersion of MMT within the matrix, increases the nucleation sites of cell growth, and improves cell structure. The cell diameter decreases from 10 to 4 μm, while the cell density increased from 4.1 × 1012 to 15.8 × 1012 cell cm−3. In addition, the cell distribution range narrows from 4–19 to 2–6 μm. Incorporating MMT‐St increases the crystallinity and thermal stability of TPU/PLA, mitigates chain relaxation at room temperature, and enhances foam dimensional stability. As a result, this leads 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.
Funder
National Natural Science Foundation of China