PAN-based fiber-reinforced carbon-carbon composites for improved fire retardancy and thermal and electrical conductivities for harsh environments

Carbon-carbon (C-C) fiber composites are a new class of materials that are used in various industries due to their exceptional chemical, thermal and electrical conductivities properties. In this study, carbon-carbon fiber composites were manufactured where polyacrylonitrile (PAN) powder was dissolved in dimethylformamide (DMF) solution, and carbon fibers with desired concentrations (20–80 wt%) were immersed into this solution as reinforcement through evaporation and solidification. The PAN-fiber systems were then stabilized at 250–270°C for 120 min in the air and subsequently carbonized at 650, 750, and 850°C for 60 min in the presence of argon gas to obtain the desired C-C fiber composites. Thermogravimetric analysis (TGA) results showed that the carbonized samples had a small weight loss of 2.5%, while actual and oxidized samples had more weight loss. Moreover, the carbonized sample surface was more hydrophobic compared to other samples due to the carbon presence and surface texture changes. Fourier-Transform Infrared (FTIR) spectroscopy peaks showed the presence of different functional groups of PAN before oxidation and carbonization, but those peaks disappeared after oxidation and carbonization. The developed carbon-carbon composite passed the UL94 vertical flame retardancy testing with a V-0 rating. Surface smoothness, proper matrix and reinforcements bonding were confirmed by scanning electron microscopy (SEM) results and the manufactured composite properties changes were validated by the confocal microscopy images. The carbon-carbon fiber composite achieved an electrical conductivity value up to 4.75 × 103 S/m after the carbonization process. The excellent thermal, chemical, and electrical properties of these composites can be useful for numerous industrial applications in different extreme environments.