Polyacrylonitrile (PAN) fiber is the most widely used carbon fiber precursor, and methyl acrylate (MA) copolymer is widely used for research and commercial purposes. The properties of P (AN-MA) fibers improve increasingly as the molecular weight increases, but high-molecular-weight materials have some limitations with respect to the manufacturing process. In this study, P (AN-MA) precursor fibers of different molecular weights were prepared and analyzed to identify an efficient carbon fiber precursor manufacturing process. The effects of the molecular weight of P (AN-MA) on its crystallinity and void structure were examined, and precursor fiber content and process optimizations with respect to molecular weight were conducted. The mechanical properties of high-molecular-weight P (AN-MA) were good, but the internal structure of the high-molecular-weight material was not the best because of differences in molecular entanglement and mobility. The structural advantages of a relatively low molecular weight were confirmed. The findings of this study can help in the manufacturing of precursor fibers and carbon fibers with improved properties.

Super engineering plastics, such as polyetherimide (PEI), are widely used in various fields owing to their multifunctional properties. PEI is used in automobiles, electronics, and medicine owing to its high thermal resistance, excellent mechanical strength, flame retardancy, and chemical resistance. In this study, melt‐spun PEI filaments were thermally drawn and the effect of the drawing process conditions on their mechanical properties was investigated. To understand the mechanical properties of various forms, such as films, sheets, granules, tubes, and rods of PEI postprocessing, it is based on analyzing the behavior in one‐dimensional structures. The mechanical properties of the PEI filaments were dictated by the draw ratio, process temperature, and cooling temperature of the thermal drawing process. In addition, maintaining the drawing process temperature around the glass transition temperature (220°C) of PEI elongated the filament by up to 80%. Furthermore, the optimized cooling temperature was 150°C and draw ratio was 50%. In conclusion, PEI filaments with excellent mechanical properties were obtained by optimizing the draw ratio, process temperature, and cooling temperature of thermal drawing. Through the behavior of the molecular and crystal structures by thermal drawing of PEI filament, it is expected to be applied to two‐ or three‐dimensional structures.