Enhancing mechanical performance of additively manufactured continuous fiber reinforced composites by constructing a thermoset-thermoplastic interlocked biphasic network

Additive manufacturing of continuous fiber reinforced thermoplastic composites offers exceptional lightweight potential and enables complex structural fabrication. However, despite high printing efficiency, this process often suffers from reduced interlaminar properties, limiting its industrial scalability. Therefore, this study develops an innovative printing system by introducing a new material concept for continuous fiber reinforced hybrid thermoset-thermoplastic composites. A thermoset-thermoplastic interlocked biphasic network is established, enabling the production of high-performance 3D printed continuous fiber reinforced dual-matrix (CFRDM) composites. This approach improves interlaminar performance while maintaining manufacturing efficiency and reduces structural warpage caused by curing-induced deformation mismatch. The interlaminar properties of CFRDM composites with varying spatial arrangements of matrix phases are evaluated via flexural testing. Compared to polyphenylene sulfide (PPS) matrix composites, CFRDM composites exhibit a 58.3% increase in flexural strength. Microscopic characterization of the interlocked dual-phase network using scanning electron microscopy and X-ray computed tomography reveals the reinforcement mechanism of the thermoset-thermoplastic interface for enhanced interlaminar properties. Additionally, key printing parameters, including matrix arrangement, printing temperature and speed, are systematically investigated for their impact on forming quality and flexural performance. Overall, the proposed strategy is shown to effectively balances high printing efficiency with superior mechanical performance. This study introduces a new additive manufacturing route for continuous fiber reinforced composites, providing a practical solution to the conventional trade-off between printing efficiency and performance. The approach holds significant potential for advancing the design and production of high-performance composite structures in additive manufacturing applications.