Conventional recycling methods typically result in the downcycling of carbon fibers, leading to shortened fibers that become unusable. A crucial measure to prevent this degradation is the use of sizing, a coating that protects the fibers during the recycling process. An innovative approach involves the use of solvolysis-resistant sizing, achieved through C-C cross-linking between the coating and the fibers. This method maintains the integrity of the fibers, making high-quality recycled material reusable.

A specialized fiber treatment device was developed, incorporating a fiber guide, a fiber spreading module, a variable holder for the plasma source, a process gas supply, an extraction system, and necessary electronics. Various extraction methods, including ultrasonic, shaker, and hot extraction, were evaluated, with hot extraction proving to be the most efficient. Experimental results indicated that a lower concentration of the polybutadiene precursor in xylene enhanced cross-linking efficiency.

Laboratory tests employed the Disc-Jet plasma source, which forms a 'plasma pillow' to prevent oxygen inclusion during fiber treatment. A nebulizer was integrated into the plasma source to ensure even distribution of the polybutadiene layer. Cross-linking tests with different gas mixtures, primarily using nitrogen, were also conducted. ATR-FTIR analysis demonstrated a significant reduction in C-C double bonds and an increase in C-C single bonds, confirming the occurrence of C-C cross-linking reactions.

These advancements hold significant potential for improving the recycling process and industrial reuse of carbon fibers, thereby promoting sustainability and efficiency in material management.