Fabrication of continuous glass fiber-reinforced dual-cure epoxy composites via UV-assisted fused deposition modeling

Abstract This paper proposes an ultraviolet (UV)-assisted fused deposition modeling (FDM) method with a dual-curing process for fabricating continuous fiber-reinforced thermosetting polymer composites (CFRTPCs). The entire approach is based on the additive deposition of fused continuous glass fiber (CGF)/epoxy (EP) filaments, which are rapidly cooled upon exiting the printer nozzle to form a solid three-dimensional (3D) object. At the same time, UV irradiation is used to activate the photoinitiator and photosensitizer to pre-cure the extruded material. The final polymerization and crosslinking reactions are achieved using a post heat treatment. Herein, the UV absorption characteristics and post heating process of the dual-cure EP matrix were investigated to demonstrate the feasibility and generality of the proposed technique. Finally, 3D printed CGF/EP samples with a 43 ± 3 wt.% fiber content exhibited a tensile strength and tensile modulus of 272.51 ± 5.12 MPa and 8.01 ± 0.45 GPa, respectively; flexural strength and flexural modulus of 299.36 ± 6.16 MPa and 8.35 ± 0.18 GPa, respectively; and interlaminar shear strength of 34.06 ± 0.83 MPa. The combination of UV irradiation and post heat treatment offers a rapid, feasible, and effective dual-cure solution for 3D printing of CFRTPCs, which could be a reliable fabrication method for the development of thermosetting composite systems used in various applications.