Jana, Asmita, et al. Science advances, 2022, 8(11), eabn1905.
Pitch feedstocks can be melt processed to make fibers, a precursor processing route that requires less capital investment than carbon fibers (CFs) made from PAN precursor fibers. To overcome the performance differences caused by the heterogeneity of pitch, this work proposes an experimentally derived and validated parametric modeling framework with predictive capabilities for the fabrication of pitch-based CFs. It is found that the density, and to a lesser extent the arrangement and functionality of the molecular constituents determine the mechanical properties of CFs more than their size and shape.
Experimental fabrication of pitch-based CFs
· The pitch powder samples were transformed into fibers through a single-filament extrusion system utilizing a barrel-and-plunger design. A spinneret with a single hole, measuring 150 μm in diameter and having a length (L)/diameter (D) ratio of 5, was employed to create the filament. The spinning process took place at temperatures ranging from 40° to 50°C above the pitch softening point. The fibers were gathered on a roll using a winder set to the maximum speed possible in revolutions per minute while ensuring stable fiber drawing for a minimum of 5 minutes.
· Sections of three-inch-long fiber bundles were obtained from the rolls, placed in a graphite crucible, and oxidized according to optimized methods for each sample. Subsequently, the oxidized fiber bundles were carbonized in a furnace under a flow of inert gas at a ramp rate of 300°C/hour until reaching a final temperature between 1200 and 1300°C.
