3D Printable Dual-Cured PUA Elastomer Sensors: Low Viscosity, Volume Shrinkage, Heat Treatment Temperature and Excellent Mechanical Properties

Abstract

The dual-curing polyurethane acrylate elastomers are researched to obtain 3D printable elastomers with high tensile strength and elongation at break. This resin is applied to 3D print a complex lattice structure, with a viscosity of 407.4 mPa s at 25°C, and a wavelength of 405 nm ultraviolet. Then the 3D printer is heat-treated at 93.79°C; its volume shrinkage rate is only 0.54%, and its tensile strength and break elongation are 15.5 MPa and 476.0%, which are enhanced 61.5% and 143.9% compared to simple photopolymerization. Because this 3D-printed elastomer occurred two crosslinking reactions through the dual thermal curing, one is between the NCO groups and the amine groups, and the other is between the epoxy groups and the amine groups. Therefore, an interpenetrating network system with a crosslinked structure is finally formed in our elastomer, which has satisfactory performance to meet the requirements of 3D printing, such as low viscosity, low heat treatment temperature, low volume shrinkage, and high mechanical strength. On this basis, two types of conductive fillers are added. The results of electrical tests and dynamic detection tests show that the modified elastomer has excellent sensitivity and stability and is expected to be used in flexible sensors.