Enhancing interfacial bonding in fused filament fabricated continuous fiber-reinforced polymers via process control

Fused filament fabrication (FFF) printed continuous fiber reinforced polymers (CFRPs) are useful in a wide variety of industries. However, their inherently low interfacial bonding strength reduces their effectiveness in higher load applications. Therefore, this study aims to determine which printing process parameters can improve interfacial bonding strength by evaluating changes to interlaminar and intralayer shear strength, bending stiffness, and mode of failure. It was determined that an increased nozzle temperature, an increased buildplate temperature, applying more tension to the fiber during printing, and coextruding more matrix material with the fiber can individually improve the interfacial bonding strength of FFF-printed CFRPs. Increasing the temperature of the part during printing by increasing the buildplate temperature provided the greatest improvements, with increases of 50% to interlaminar shear strength and 56% to intralayer shear strength, and further investigation into optimizing the environment temperature during printing is needed. Additionally, when combined, these process parameters can increase interlaminar shear strength by 78% and bending stiffness by 25%, indicating that optimizing and combining multiple process parameters is the best strategy for improving interfacial bonding strength. These findings are useful for increasing the mechanical properties and improving the manufacturing process of FFF-printed CFRPs to help broaden their application.