Influences of heat treatment on mechanical properties of SCF/PEEK composites in FDM‐3D printing process with UV laser assistance

• Published in: Polymer composites 2024-10, Vol.45 (14), p.12597-12610
• Main Authors: Huang, Chuanhao, Lv, Dongxi, Zhu, Yingdan, Chen, Gang, Chen, Mingda, Zhang, Yi, Han, Yu, Wu, Huaping
• Format: Article
• Language: English
• Subjects: Carbon fibers; Cracks; Crystallization; Fiber lasers; Fused deposition modeling; Heat treatment; Interfacial shear strength; Interfacial strength; interlayer bonding behavior; Interlayers; Laser beam heating; Lasers; Mechanical properties; Molecular diffusion; Polyether ether ketones; Residual stress; SCF/PEEK composites; Shear strength; Three dimensional composites; Three dimensional printing; Ultraviolet lasers; Warpage
• ISSN: 0272-8397; 1548-0569
• DOI: 10.1002/pc.28653

Fused deposition modeling (FDM) process with laser assistance can effectively enhance the interfacial strength of short carbon fiber/poly‐ether‐ether‐ketone (SCF/PEEK) composites. However, excessive crystallization of the semi‐crystalline matrix generally results in irregular shrinkage, which seriously deteriorates dimensional accuracy of composite specimens. To overcome this issue, we establish a novel heat treatment technique by the combinations of laser assistance and post‐treatment to improve the interlayer properties and dimensional accuracy simultaneously. It is found that lateral cracks at the interlayer interfaces can be completely eliminated at laser pre‐heating temperature Tx=210°C, due to the reduction of temperature gradient and residual stresses. The further increased Tx evidently promotes molecular diffusion and crystallization behaviors, thus increasing the interlaminar shear strength of FDM‐printed specimens. The post‐treatment temperature Tp visibly promotes mutual diffusions of the molecules and formations of the perfect crystals, strengthening the interlayer adhesion of specimens. The proposed combination technique can increase the interlayer strengths of composite specimens by approximately 22.5%, while their warpage deformations are suppressed simultaneously. Highlights Pre‐heated temperature 210°C was a threshold for eliminating lateral cracks at interlayer interfaces. Post‐treatment significantly promoted molecular diffusion and crystallization behaviors. A novel technique was established to improve interlayer strength while suppressing warpage. The combination technique could increase the interlayer shear strength by approximately 22.5%. Improvement effects of heat treatment technique on interlaminar shear strength and optimization of post‐treatment parameters.