Computational assessment of effect of porosity on thermal conductivity of 3D-printed PEEK/carbon-fiber composite

The three-dimensional (3D) printing of polymer matrix composites has attracted considerable attention. However, the addition of filler materials to the extruded polymer matrix results in inner voids within the beads along with larger voids, called intervoids, which are generated between the beads during the 3D printing process. These voids degrade the thermal transport properties of 3D-printed polyether ether ketone (PEEK) and PEEK/carbon-fiber composites. The effects of these pores (i.e., their number, size, and location) on the thermal conductivity of 3D-printed PEEK and a PEEK/carbon-fiber composite were investigated using a multiscale finite element approach. The presence of the carbon fibers mitigated the effect of the pores on the thermal conductivity of the PEEK/carbon-fiber composite, particularly along the longitudinal direction. Moreover, the inner voids had a dominant effect on the PEEK and PEEK/carbon-fiber composite. Finally, the orientation of the intervoids had no effect on the thermal conductivity of the printed materials.