Printing path induced temperature history and interfacial properties of 3D printed continuous nature fiber reinforced polypropylene composites

The mechanical properties of continuous ramie fiber reinforced polypropylene (CRFRPP) are constrained by limited interlayer adhesion, which is dependent on the temperature history and attributed to the weak pressure in the fused filament fabrication (FFF) process. To study the relationship between the temperature history and interlayer performance of the CRFRPP. The characteristic of temperature history for the concentric, zigzag 1, and zigzag 2 printing path were investigated through in-situ monitoring using an infrared camera. The interfacial performance of specimen with different printing paths was studied through T-peel test, and morphological properties of the specimens before and after T-peel test were investigated. Finally, the mechanical properties of specimens with different printing paths were further investigated through three-point bending tests. The results showed that specimens with the concentric path presented the longest effective welding time compared to zigzag 1 and zigzag 2 specimens, attributed to the different thermal behaviors in sublayer. The interfacial adhesive force of the concentric specimen was 103 % higher than that of zigzag 2, and zigzag 1 had a 51 % higher interfacial adhesive force than zigzag 2 after the T-peel test. The morphological analysis revealed that concentric specimens presented fewer defects in cross-section and irregular fracture surface compared to other printing paths, in the current ranges of study. The superior interlayer properties of concentric specimens resulted in better flexural strength and flexural modulus, with failure modes characterized by breakages of the fiber and matrix.