Asphaltene-Recycled Polyethylene Terephthalate (rPET) Blends as Sustainable Carbonaceous Fiber Precursors

Bitumen asphaltenes (AS) are investigated as promising precursors for carbon fiber due to their low cost and high concentration of aromatic compounds. However, as-received AS exhibit poor melt-spinnability, which can be significantly improved by blending them with miscible polymers. In this work, blends of AS and recycled poly(ethylene terephthalate) (rPET) were investigated for their potential as precursors for sustainable partially carbonized fibers. This process is sustainable because it redirects two waste streams into feedstock for a higher value product, does not require thermal pretreatment of the AS, and avoids the use of solvents normally required to purify AS. The effect of the blending ratio on the viscoelastic properties of the AS-rPET blends and its role in melt-spinning was investigated. AS-rPET fibers were melt-spun, stabilized via oxidation, and partially carbonized. Scanning electron microscopy indicated that the produced partially carbon fibers had diameters of 40.75 ± 5.12 μm, representing an order-of-magnitude reduction in diameter compared to fibers derived from pure AS. Tensile testing of individual partially carbonized fibers determined the maximum tensile strength and Young’s modulus to be ∼0.29 ± 0.13 GPa and 24.9 ± 6.4 GPa, respectively.