Assessment of carbon fiber incorporation effects on overall characteristics and properties of 3D-printed PLA

Recently, there"s been increased research interest in carbon fiber-reinforced polymer composites for additive manufacturing. Understanding the intricate effects of these reinforcements on the characteristics and properties of printed components is essential. This study aimed to evaluate the impact of carbon fibers on the chemical characteristics of 3D-printed poly(lactic acid) (PLA) and, consequently, its thermal, electrical, and mechanical properties. For this purpose, its features were compared to those of natural PLA printed under identical conditions. Chemical characterization utilized Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, and X-ray Diffraction (XRD), while thermal analysis employed Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) tests. Electrical properties were determined by resistance, resistivity, and conductivity measurements, while mechanical properties were assessed through various tests, including tensile, flexural, impact, and notch sensitivity, along with hardness measurements. Raman spectroscopy identified D and G bands in carbon fiber-reinforced PLA, while FTIR spectra indicated no chemical interactions of the fiber reinforcement with the PLA matrix. XRD patterns showed low crystallinity and pigment-associated peaks, highlighting specific peaks for crystalline PLA and carbon fiber in reinforced PLA. DSC results indicated an increase in PLA"s melting and crystallization temperatures with fiber incorporation, while TGA analysis revealed a decrease in the onset temperature of thermal decomposition for reinforced PLA. Carbon fiber reinforcement decreased tensile and flexural strength while enhancing elastic modulus and deformation under tension and flexion. Moreover, the impact energy necessary for PLA fracture rose with fiber incorporation. PLA hardness increased with the carbon fiber reinforcement. Fractographic analysis reveals that PLA polymer experiences intralayer brittle fractures, while carbon fiber-reinforced PLA composites exhibit interlayer fractures.