Effect of Blended Polyphenylene Sulfide on Spinnability of Mesophase Pitch and the Properties of Carbon Fiber

ABSTRACT Spinning mesophase pitch is usually a huge challenge because of the brittleness and poor mechanical properties, which restrict the diameter reduction and continuous time as well as the successive processing as stabilizing and carbonizing. In this paper, polyphenylene sulfide (PPS) was blended into a naphthalene mesophase pitch to improve the spinnability based on the hypothesis that intermolecular force between the small rigid lamellar molecules of pitch could be strengthened by the long flexible chains of PPS. The results show that the spinnability was significantly improved and the strength of pitch fiber was enhanced with no more than 5.0 wt.% PPS blending, which is crucial for subsequent successive processing. The maximum draw‐down ratio at which continuously spinning for 22 min was increased from 47 to 92, the pitch fiber diameter was reduced from 29.3 to 20.9 μm, and correspondingly the carbon fiber diameter was reduced from 25.1 to 17.3 μm after 1150°C carbonization. The splitting structure of blended carbon fiber was markedly suppressed and the carbon yield was slightly decreased and a little higher than the theoretical value. Beyond our expectation, the tensile strength and modulus of carbon fiber were increased by 41.7% and 16.6%, respectively.