From Polyacrylonitrile, its Solutions, and Filaments to Carbon Fibers II. Spinning PAN-Precursors and their Thermal Treatment

Based on the results of Part 1 of this work, we have chosen acrylonitrile copolymers for preparing dopes in dimethyl sulfoxide (DMSO). Modeling the spinning process in static conditions was carried out by following the evolution of the interaction between a drop of solution and precipitant. In addition, the diffusion zone was controlled by the laser-interference method. Fibers were spun on a laboratory stand. It was found that the optimal ratio of DMSO to water in a coagulation bath was 85/15. The analysis of the structure of different fibers (including fibers with carbon nanotubes) demonstrated the superposition of crystalline phase and orientation-disordered mesophase. The evolution of this structure could provide the answer to the question of which structure of “white” fibers is best for obtaining high-quality “black” fibers. Measurement of the structure and mechanical properties of fibers allowed us to optimize the technology of thermal treatment of fibers including the intensity of heat output in the stages of thermal-oxidative stabilization and carbonization as well as the strain characteristics and applied tension. Model carbon fibers have a satisfactory complex of mechanical properties. We aimed to choose a set of experimental approaches as a proper way to produce high-strength carbon fibers.