Recyclability and reutilization of carbon fiber fabric/epoxy composites

Solid carbon fiber/epoxy laminates manufactured by liquid resin infusion of twill fabric reinforcement are recycled in a bath of boiling sulfuric acid to separate the fibers from the matrix. The recycled reinforcement consists of long fibers arranged in a random, entangled mat. Using the same epoxy matrix and infusion materials and process, the recycled fibers are reutilized to manufacture solid laminates. The physical properties of the recycled laminates are evaluated by means of pulse-echo ultrasound, visual microscopy, and fiber volume content. The average fiber volume content of the recycled laminates is 33%, compared to the 62% of the twill laminates. The mechanical properties of the recycled composite include tension modulus and strength, compression modulus and strength, three-point bend flexure strength, and short beam shear strength. The properties are compared against the values of the twill reinforcement with quasi-isotropic stacking sequence. Results show that the recycled material offers promising elastic properties and strength values, similar to those of advanced carbon fiber sheet molding compounds, and therefore can be used as structural material.