Selective Laser Sintering of High Temperature Thermoset

Selective Laser Sintering (SLS) is a branch of powder bed fusion additive manufacturing (AM) technique in which laser is used as a power source to sinter polymer powder materials. The laser targets the points in space defined by a 3D computer model and binds the material together to create a solid structure. Although thermoplastic materials (PA12, PA6, et) have been successfully demonstrated in SLS, printed 3D objects from these materials exhibit a lack of polymer interchain connection in print direction, resulting in poor mechanical properties and poor fatigue behavior. This deficiency of thermoplastics has encouraged to print high-performance thermosets using SLS. In this research, bismaleimide (BMI) resin thermoset powder was successfully printed using SLS with a two-step melting and post curing process. Dimensional and thermal stability of printed thermosets after curing is proved in this research for the very first time. Almost zero-dimensional change (0.033% increment in length, 0.23% increment in width, and 0.317% decrement in thickness) after curing of SLS printed thermoset part was presented. The thermomechanical property of printed BMI was characterized by dynamic mechanical analysis. Polymer crosslinking mechanism during curing process through FTIR as well as the thermal and mechanical stability of printed thermoset through compression tests have been analyzed in this research. The feasibility study demonstrates the feasibility of using SLS for printing high temperature tehermoset for variety energy and defense related applications.