Research on the performance of polyacrylonitrile-based large bundle carbon fiber during the widening process after filament assembly

Abstract Large-tow carbon fibers are increasingly utilized in the field of composite materials, owing to their unique cost advantages and superior performance. The spreading width is a critical factor influencing both the performance of the fiber bundle and its impregnation properties. In this study, four 12K small-tow bundles were combined using a filament-combining device to form 48K large-tow bundles with varying spreading widths. Tensile tests were conducted on the carbon fiber tow bundles to investigate their mechanical properties at different spreading widths. Additionally, a weighing method was employed to identify the optimal impregnation technique for the carbon fiber tow samples. The experimental results indicate that the tensile performance of the 48K carbon fiber large-tow bundle is enhanced when the spreading width is smaller. However, excessively small spreading widths may compromise the internal fiber alignment and resin impregnation efficiency. Thus, the mechanical properties of the 48K large-tow carbon fiber bundle are optimized when the spreading width is 14 mm after filament combining.