PHYSICAL, MECHANICAL, AND THERMAL CHARACTERIZATION OF UNFILLED AND CARBON FIBER FILLED POLYAMIDE (PA) FILAMENTS AND CORRESPONDING FUSED DEPOSITION MODELLING FABRICATED SAMPLES

Fused deposition modelling (FDM) represents a promising domain in 3D printing techniques that fabricates objects layer by layer from 3D CAD data. While FDM excels in fabricating pure polymer composite parts, the limitations of matrix polymers necessitate the development of fiber-reinforced polymer composites. Despite polyamide's superior mechanical properties as a composite matrix, there's limited research on short carbon fiber-reinforced polyamide (PA) in FDM. Moreover, previous studies typically focus solely on evaluating the tensile properties of FDM printed parts, neglecting feedstock filament properties. Understanding and enhancing the material properties of commercially available carbon fiber polyamide (CF/PA) filament remains a challenge. This study renders a thorough examination of the microstructural changes and property evaluation pre and post-FDM printing. In this work, raster angles were examined, with a focus on their direct influence on mesostructure, solid-state sintering mechanics, and resulting composite part characteristics through inter-bead and inter-layer bonding, affecting voids, fibers, and the base material matrix. Results show significant fiber breakage, leading to a 31.30% reduction in the average length of fibers from filament to printed parts. While the filament maintains high fiber alignment, printing occasionally leads to misalignment. Tensile tests reveal anisotropic properties in FDM samples with varied raster angles. Short carbon fibers decrease strength but boost Young's modulus in filament-to-FDM conversion. Examination of fractured surfaces reveals distinct failure modes for filament and printed test coupons. TGA confirms nearly 20 wt.% carbon fiber in the filament, with pure PA filament and samples yielding minimal residue. DSC results indicate enhanced thermal stability with carbon fiber reinforcement, while XRD reveals distinct amorphous behavior in both filament and printed parts.