Enhancing Tensile Strength and Thermal Resistance of PLA-Carbon Fiber Composites Synthesis on Conventional and 3D Printing Methods

Abstract

This study investigates the tensile characteristics and thermal conductivity of PLA-carbon fiber (CF) regular composites and 3D printed PLA-CF composites, focusing on the impact of varying carbon fiber weight fractions. The carbon fiber reinforcement percentages range from 5 wt.% to 30 wt.%, allowing for a thorough comparison of mechanical and thermal properties. The analysis reveals a consistent improvement in tensile strength for both composite types, with PLA-CF regular composites achieving a peak 192% improvement at 25 wt.% and 3D printed PLA-CF composites showing a 209% improvement at 20 wt.%. The enhancement is attributed to effective fiber-matrix interactions and load transfer mechanisms. However, beyond the optimal weight fractions, tensile strength decreased slightly due to fiber agglomeration, poor dispersion, and void formation.FESEM morphology analysis provided critical insights into the failure mechanisms, indicating smooth fracture surfaces at lower fiber contents (5 wt.% to 15 wt.%), followed by enhanced fiber bridging and pull-out at peak fiber loadings. At higher fiber contents, fiber misalignment and void formation were observed, leading to reduced tensile strength.In terms of thermal performance, PLA-CF regular composites exhibited a 74% reduction in thermal conductivity, while 3D printed PLA-CF composites demonstrated an even greater 92% reduction, highlighting their superior thermal resistance. The reduction in thermal conductivity is attributed to fiber agglomeration and the FDM process used in 3D printing, which introduces interfacial thermal resistances. These findings underscore the importance of optimizing both fiber loading and manufacturing techniques to enhance the mechanical and thermal properties of PLA-CF composites, particularly for applications demanding high strength and thermal stability.