Molecular-weight-dependent Interplay of Inelastic Mechanisms in Cold Spray Deposition of Glassy Polymers
발표자
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초록
내용
The solid-state consolidation of polymer feedstock powders in cold spray additive manufacturing occurs at ultra-high rates (UHR＞106 s-1). To investigate the influence of molecular weights (MWs) of glassy polymers on the unique UHR deposition mechanism, laser-induced projectile impact testing (LIPIT) is introduced. In LIPIT, 40 µm diameter polystyrene microparticles (PS-µPs) having different MWs (10, 20, 40, 100 kDa) are accelerated and collide with a stationary PS or silicon substrate. In the collision with the silicon substrate, PS-µPs demonstrate substantially less collision-induced fragmentation. While the brittle fragmentation and shattering of the PS-µPs are suppressed by increasing MW, the adhesion of the PS-µPs is observed only for the silicon substrate at collision velocities above 435 m/s (for 40 kDa) and 645 m/s (for 100 kDa). This implies that the adhesion of PS µPs is determined by two competing factors, UHR fracture strength of solid PS and dynamic viscosity of PS melts. *This research was sponsored by the U.S. DEVCOM Army Research Laboratory under the Cooperative Agreement No. W911NF-19-2-0152.