Effects of Irradiation Temperature on Porosities in <scp>UV</scp> Laser‐Assisted <scp>FDM</scp> ‐ <scp>3D</scp> Freedom Extrusion of <scp>SCF</scp> / <scp>PEEK</scp> Composites

ABSTRACT In the traditional extrusion‐based fused deposition modeling (FDM) process, the intrinsic voids generated in the monofilament preparation process will inherit into the printed components, which seriously deteriorates their mechanical and fatigue properties. The present investigation proposed a novel UV laser‐assisted method to reduce these inherent voids of short‐carbon‐fiber‐reinforced polyether ether ketone (SCF/PEEK) composites. Moreover, associated mechanisms were discussed with respect to the potential effects of irradiation temperature on material extrusion. It was found that the elliptic cavities induced by ruptures of the extrudate surface were attributed to the combination effects of molecular disentanglements and bubble expansions after exceeding the nozzle end‐face. The bubble coalescence in the liquefier brings about a significant increment of the void dimensions at extrudate interior. Extensive round cavities covered by thin wrinkles emerged at the irradiated region, and these porous structures result from directional migrations of coalesced bubbles. These migrated bubbles were extruded during the formal deposition process, significantly reducing the porosity of printed straight lines. Specifically, the porosity of the straight line at laser preheat temperature T x = 296°C decreases by 47.7%, compared with that of the monofilament.