A Thermoset Shape Memory Polymer-Based Syntactic Foam with Flame Retardancy and 3D Printability

Here we report a thermoset shape memory polymer-based syntactic foam inherently integrated with flame retardancy, good mechanical properties, excellent shape memory effect, and 3D printability. The syntactic foam is fabricated by incorporating a high-temperature shape memory polymer (HTSMP) as the matrix, with 40 vol % hollow glass microspheres (HGM) K20, K15, and K1 as fillers. Compressive behavior, strain-controlled programming followed by free recovery, stress recovery, and flame retardancy of these three syntactic foams were studied. Dynamic mechanical analysis and thermal characterization validate their high glass transition temperature (T-g = similar to 250 degrees C) and excellent thermal stability. Our results suggest that the foam consisting of K20 HGM exhibits high compressive strength (81.8 MPa), high recovery stress (6.8 MPa), and excellent flame retardancy. Furthermore, this syntactic foam was used for three-dimensional (3D) printing by an extruder developed in our lab. Honeycomb, sinusoidal shapes, and free-standing helical spring were printed for demonstration. This high-temperature photopolymer-based syntactic foam integrated with high T-g, flame retardancy, high recovery stress, and 3D printability can be beneficial in different sectors such as aerospace, construction, oil and gas, automotive, and electronic industries.

Automated summary

Here we report a thermoset shape memory polymer-based syntactic foam with flame retardancy, good mechanical properties, excellent shape memory effect, and 3D printability. The foam consists of a high-temperature shape memory polymer as the matrix and hollow glass microspheres as fillers. Compressive behavior, programming and recovery, stress recovery, and flame retardancy were studied. The foam shows high mechanical strength, recovery stress, and flame retardancy, and can be 3D printed.