Performance and Thermal Properties of 3D Printed CF-Reinforced PLA Monofilaments

This study reports the fabrication of carbon fiber-reinforced poly(lactic acid) (CF-PLA) monofilaments using 3D printing technology. The effects of print head movement speed and retraction rate on the diameter of the CF-PLA monofilaments were investigated. The surface morphology and properties were analyzed using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The CF-PLA monofilaments were also printed into boards with varying CF content, and the mechanical properties of these boards were assessed. The results showed that the optimal printing parameters were a nozzle diameter of phi 0.4 mm, fiber feed rate (Vf) of 3 mm/s, print head movement speed (Vm) of 40 mm/s, and retraction speed (Vr) of 5 mm/s. At a CF-PLA monofilament diameter of phi 135 mu m, the tensile strength and Young's modulus reached maximum values of 48.3 MPa and 2481.8 MPa, respectively. Numerous CF monofilaments (approximately 135 mu m in diameter) were observed on the surface and within the CF-PLA boards, significantly enhancing their strength. When the CF content was 4 vol%, the thermal decomposition temperature of the CF-PLA monofilament was 312.53 degrees C. At 8 vol% CF content, the thermal decomposition temperature increased to 342.62 degrees C-approximately 30 degrees C higher than that of the monofilament with 4 vol% CF. The CF-PLA monofilaments fabricated at 8 vol% demonstrated high thermal stability.