A low-density polymer/CrMnFeCoNi composite with high strength and high damping capacity

•By taking a porous CrMnFeCoNi HESMA as the skeleton, whose pores are filled with the composite composed of CNTs and PU/EP IPN, a novel composite was prepared.•Correlations between the microstructure and mechanical properties/damping capacities of composites were discussed.•A triple-phase micromechanical model was introduced. Simulation results indicate that the coupling of multiple damping mechanisms is the reason for the high ground-state damping, and interface damping is the main damping mechanism.•The superposition of the ε → γ reverse martensite transformation peak of CrMnFeCoNi skeleton and the glass transition peak of CNTs/polymer composite realizes the high damping capacity within a wide temperature range. A novel damping composite was successfully prepared by taking a porous CrMnFeCoNi high-entropy shape memory alloy as the skeleton and filling its pores with the composite composed of carbon nanotubes and polyurethane/epoxy interpenetrating polymer networks. When the porosity, pore size and CNT loading are 80 %, 1.2 mm and 2 wt%, respectively, the compressive strength, elastic modulus and energy absorption capacity of the composite are 35.7 MPa, 1.31 GPa and 23.1 MJ/m3 (ε = 65 %), respectively. Furthermore, it has a mere density of 2.525 g/cm3. Its loss factor is greater than 0.093 and can reach a maximum of 0.145 within the temperature and frequency range of 20 ∼ 150 ℃ and 0.1 ∼ 200 Hz. A triple-phase micromechanical model was utilized to explore the damping mechanism of composites. Results indicate the coupling of multiple damping mechanisms is the reason for the high ground-state damping of composites, and interface damping is the primary damping mechanism. The superposition of the ε → γ reverse martensite transformation peak of the CrMnFeCoNi HESMA skeleton and the glass transition peak of the CNTs/polymer composite matrix realizes the wide damping temperature range of the composite.