Recently, 3D printing of fiber-reinforced composites has gained significant research attention. However, commercial utilization is limited by the low fiber content and poor fiber–resin interface. Herein, a novel 3D printing process to fabricate continuous fiber-reinforced thermosetting polymer composites (CFRTPCs) is proposed. In brief, the proposed process is based on the viscosity–temperature characteristics of the thermosetting epoxy resin (E-20). First, the desired 3D printing filament was prepared by impregnating a 3K carbon fiber with a thermosetting matrix at 130 °C. The adhesion and support required during printing were then provided by melting the resin into a viscous state in the heating head and rapidly cooling after pulling out from the printing nozzle. Finally, a powder compression post-curing method was used to accomplish the cross-linking reaction and shape preservation. Furthermore, the 3D-printed CFRTPCs exhibited a tensile strength and tensile modulus of 1476.11 MPa and 100.28 GPa, respectively, a flexural strength and flexural modulus of 858.05 MPa and 71.95 GPa, respectively, and an interlaminar shear strength of 48.75 MPa. Owing to its high performance and low concentration of defects, the proposed printing technique shows promise in further utilization and industrialization of 3D printing for different applications.

Tribological properties of glass fiber-reinforced polymer (GFRP) composites used in reciprocating contact should be improved to secure the efficiency and safety because of risks of abrasion, adhesion, and fatigue deficiency amidst fiber, matrix, or interphase. This paper investigates the influence of graphene reinforcement on the wear resistance of a GFRP composite. Graphene was integrated into a typical GFRP composite as the surface coating using a modified resin film infusion method with the percolating paper assisted. Dry reciprocating sliding tests were performed against a stainless steel ball moving in a direction 45 degrees to the fiber orientation. The morphology of the worn surface was observed, and the corresponding wear mechanisms are discussed. Results suggest that the prepared graphene coating improves the wear resistance of the GFRP composite. The protected GFRP laminates remained intact during the first 20 min of the wear test and only a small fraction of fibers were broken after 60 min test. Furthermore, abrasive debris and fiber breaks originating from composite were markedly reduced, likely owing to the formation of a protective transfer film between the surface of the modified composite and the rubbing counterpart.