A dual-mode activated, 3D-printable composite foam resin for rapid microwave and thermal expansion

Abstract

In this study, a dual-mode activated 3D printable composite foam resin is formulated that rapidly expands under both thermal and microwave energy. This composite resin consists of UV-curable aliphatic urethane acrylate oligomers and monofunctional acrylate monomers-based resin along with expandable microsphere and fumed silica nanoparticles. Vat photopolymerization process (VPP) is used to fabricate a stable crosslinked matrix that accommodates volumetric expansion in the subsequent steps of thermal and microwave heating. Microwave heating of the samples attains full expansion in under 2 min, compared to 30 min with thermal heating. The degree of curing reached 70.9 % for microwave activation and 36.8 % for thermal, while both the methods exhibited identical density (137 kg/m³) but with noticeable differences in internal pore morphology. Thermally foamed samples exhibited higher compressive modulus (6.69 MPa), specific energy absorption (SEA 6.18 J/g), and yield strength of (1.08 MPa) whereas microwave-foamed samples showed higher energy absorption in tension (SEA 1.26 J/g) and faster processing. ANSYS LS-DYNA was used to validate the experimental compressive behavior of the expanded foam activated by both methods. This dual-energy-responsive foam resin enables the digital fabrication of lightweight foams with tunable morphology and mechanical properties. Potential applications of such materials include wearable impact protection, such as helmet liners, and customized energy-absorbing components for aerospace, automotive, and defense sectors.