Preparation of thin carbon fibers from phenol–formaldehyde polymer micro-beads dispersed in polyethylene matrix Original Research Article

Phenol–formaldehyde polymer (PF) micro-beads smaller than a few micrometers were blended into a polyethylene (PE) matrix with the ratio of 3:7 for PF:PE by weight. PF and PE showed ca. 50 and 0 wt% carbon yields after heating to 600°C in a nitrogen atmosphere, respectively. The PF–PE blend was melt-spun continuously, stabilized in an acid solution, neutralized with aqueous ammonia, washed with deionised water, dried and finally carbonized at 600°C for 10 min under a nitrogen atmosphere. The stabilized fibers were several tens of micrometers in diameter. After carbonization of the fiber, a bundle of PF-derived thin carbon fibers smaller than several hundred nanometers in diameter was left after removal of the PE matrix. The bundle was easily separated into thin fibers. A thinner fibers showed a more irregular surface, this could possibly have been caused from a larger contraction of the PF fiber than of the PE matrix during the stabilization process. The present method can be used for a mass production of long and thin carbon fibers.