4. Experimental development of a pyrolysis technology for unwinding carbon composites for filler reuse

Carbon composites are widely used in various components of modern technology, leading to an increasing accumulation of composite waste. An urgent challenge is the development of methods for recycling carbon composites and enabling the reuse of their constituent fi llers. In order to reuse the fi ller, it must be separated from the matrix while maintaining its continuous structure to preserve its original properties as much as possible. The primary task during separation is melting the polymer matrix–either a thermoplastic or thermosetting resin. Various methods are available to address this challenge, including mechanical recycling, solvent-based recovery, and thermal recovery methods. This study describes the process of separating a carbon tow via pyrolysis, using as an example a tubular structure manufactured through wet winding of T800-type carbon fi ber impregnated with epoxy resin. During the experimental evaluation, the pyrolysis of the wound composite was conducted at temperatures ranging from 350°C to 850°C. A continuous carbon tow was successfully extracted after 20 minutes of thermal exposure. To assess the properties of the recovered tow and compare them with those of the as-delivered tow, strength tests, weight loss measurements, and microstructural analysis were carried out. The results showed a fourfold reduction in the tensile strength and a twofold decrease in mass after pyrolysis. Microstructural examination revealed the presence of micropores in the recovered tow, correlating with the observed degradation in strength and mass loss. The study confi rms the feasibility of unwinding carbon composites via high temperature thermal decomposition (pyrolysis) and successfully recovering a continuous carbon tow.