This study shows the utilization of recycled carbon fibers (rCF) in nitrile butadiene
rubber (NBR) to produce sustainable, high-performance elastomer-based mixtures. Recycled
carbon fibers, sourced from composite waste, were incorporated into the NBR matrix
with different concentrations using an internal mixer for compounding and hot pressing
for vulcanization. Tensile, hardness, tear and abrasion tests, and a scanning electron
microscopy study were performed to show the effects of rCF. The results indicate that
moderate fiber contents significantly enhance the stiffness and tensile strength of
NBR without compromising its inherent elasticity. Twenty phr recycled carbon fiber
increased tensile strength by 15% but decreased strain by 16% and almost doubled stiffness
compared to the reference. The addition of carbon fibers caused an increase in hardness
proportionally with the amount of reinforcement. 50 phr rCF increased Shore A hardness
by 30%. When rCF was added, abrasion resistance increased significantly; 10 phr carbon
fiber halved the amount of abraded material. Microscopic examinations confirmed the
significance of fiber dispersion and adequate bonding at the matrix–fiber interface
for optimal load transfer. The possibility of foaming was analyzed, and the hypothesis
was proved. The results demonstrate the viability of recycled carbon fibers as a reinforcement
in NBR, which also highlight the environmental and economic benefits associated with
recycling composite materials in the rubber industry.
