Enhancing Asphaltene Spinnability via Polymer Blending

The drive toward carbon neutrality has led to extensive research on converting asphaltenes (AS) into value-added products. AS are composed of large polyaromatic and polyaliphatic cyclic systems with a low H-to-C ratio, making them well-suited to produce carbonaceous materials, such as carbon fibers. However, the inherent variability in the viscoelastic properties of AS, which stems from their sourcing, poses challenges to the spinnability of AS-derived carbon fibers. In this study, we intentionally chose an AS sample that inherently lacks the ability to be spun continuously and enhanced its viscoelasticity by incorporating thermoplastic polymers with comparable Hansen solubility parameters. Three weight fractions of polystyrene (PS), poly(methyl methacrylate), and poly(ethylene-co-vinyl acetate) (EVA) (5, 10, and 20%) were added to pristine AS powder by two common mixing methods: solution mixing and melt blending. All three blends of AS and polymers exhibited enhanced spinnability compared to pure AS, with the EVA blend showcasing the highest efficacy in the melt-spinning process, producing fibers with the smallest diameter and the least amount of surface defects. Furthermore, we established a correlation among the microstructure of the blends, their rheological properties, and their spinnability. Confocal imaging confirmed enhanced compatibility between AS and EVA, with the blend exhibiting a lower rheological signature compared with its individual components. This can be attributed to the potential of EVA to break down larger AS aggregates, facilitating improved alignment during high-temperature spinning.