Comparative Analysis of Thermal Recycling Approaches for Carbon Fiber Recovery from CFRP Waste

The development of lighter, high-performance materials, such as composite materials, is in growing demand, especially in the automotive sector, but it generates significant waste. Therefore, the present study introduces thermoset composites of carbon fiber (CF) and epoxy resin (ER) as a material with great potential for achieving a maximum weight reduction in automotive vehicles. In this study, a thermal recycling route using both conventional oven and microwave oven pyrolysis to recover CF from CF/ER composite waste generated in the automotive sector was performed. Pyrolysis in a conventional oven under nitrogen with durations of 20, 45, and 60 min resulted in a 29.1% weight loss. Additionally, microwave oven pyrolysis was conducted under both nitrogen and oxidative atmospheres with durations ranging from 10 to 20 min, leading to a weight loss of 34.4% in a nitrogen atmosphere and 40.3% in an oxidative atmosphere. The recovered CF was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), contact angle measurements, and tensile testing of the CF monofilaments. Thermal recycling using a microwave oven enabled the recovery of clean and intact CF without compromising its mechanical properties, facilitating its reuse in new applications and processing. Based on the results, thermal recycling using a microwave oven shows promise for CF recovery with low pyrolysis time, resulting in greater energy efficiency during thermal recycling.

The recovery of carbon fibers from structural composites is a sustainable alternative for producing new components, contributing to the circular economy and conserving mineral resources.