Compression-Induced Mechanical Pore Opening in Microcellular Polyurethane Elastomers: Decoupling Open Porosity Effects From Matrix Contributions

This study presents a stress-induced pore rupture strategy for decoupling cellular architecture from matrix properties in microcellular polyurethane elastomers. Controlled mechanical compression was applied to a single formulation to tune open porosity (14%–67%) while preserving matrix chemistry and nanoscale morphology, as verified by FTIR, XRD, and SAXS analysis. In situ CT imaging revealed distinct deformation mechanisms: closed-cell structures deformed through gradual pore compression dominated by gas-spring effects, whereas open-cell networks exhibited immediate strut reorientation and extensive compaction governed by solid matrix deformation. Quantitative analysis showed that cellular deformation accounted for 81.2%–86.8% of total strain in open-cell foams, compared with 69.2%–74.1% in closed-cell systems. Increasing open porosity reduced stiffness by 27% but enhanced energy dissipation by 63%. Digital image correlation further demonstrated localized strain in closed-cell foams and uniform stress redistribution in open-cell architectures. Vibration testing revealed complementary performance, with high-porosity foams suppressing resonance through viscous damping and low-porosity foams providing superior high-frequency isolation. This work establishes microstructure-guided design principles for programming dynamic mechanical properties in polymer foams, offering a pathway toward lightweight material for vibration control and impact protection.