Design and Effect of a Resin Infiltration Method to Enhance the Interlayer Adhesion of Additively Manufactured PEEK Parts

This study investigates post-processing treatments aimed at enhancing the mechanical properties of Polyether Ether Ketone (PEEK) parts fabricated via Fused Filament Fabrication (FFF). FFF-printed PEEK components often exhibit anisotropy and weak interlayer adhesion, which limit their structural performance. To address these issues, a resin infiltration treatment is proposed that yields improvements in flexural strength and strength-to-weight ratio across specimens with different infill percentages. The effectiveness of resin infiltration is compared to that of a thermal post-processing treatment. Experimental results indicate that, although thermal treatment enhances crystallinity, it does not substantially improve interlayer bonding or mitigate anisotropy. In contrast, resin infiltration significantly enhances flexural strength, particularly in specimens with lower infill percentages, by effectively filling pores and reinforcing interlayer adhesion. Overall, the findings demonstrate that vacuum-assisted thermosetting resin infiltration is a promising post-processing technique for improving the mechanical performance of 3D-printed PEEK, achieving a mean flexural strength of up to 34 MPa, approximately 80% higher than that of untreated specimens with 100% infill. Additionally, a cost analysis comparing both post-processing methods is presented, highlighting the cost-effectiveness of resin infiltration as a viable solution to overcome the inherent limitations of FFF-printed PEEK.