Research on dynamic microwave low-temperature carbonization of high performance carbon fiber

Polyacrylonitrile precursor was obtained by one-step method of polymerization and spinning. After conventional pre-oxidation at 180–280 °C in air, the polyacrylonitrile pre-oxidized fiber was carbonized at 600–1000 °C by microwave heating and conventional heating in nitrogen. An infrared thermometer is used to detect the surface temperature of the fiber in real time. The dielectric loss tangent (tanδ) increases first and then decreases with increasing temperature. The intensity of the A line of the MCF-1000 sample increases, the G line gradually separates from the D line, and the ID/IG value decreases. Compared with CCF-700, the tensile strength of MCF-700 is increased by 10.06%. The microwave carbonization method creates excellent carbon fiber tensile strength at a temperature of 200 °C lower than the conventional carbonization temperature. The initial modulus of MCF-700 is 51.33% higher than that of CCF-700. Microwave carbonization can obtain carbon fiber with a higher initial modulus at a lower carbonization temperature.