Carbon fibers prepared from ionic liquid-derived cellulose precursors

Abstract

Cellulose derivative fibers were prepared via phosphorylation of cellulose with the ionic liquid (IL) 1,3-dimethylimidazolium methyl-H-phosphonate [MMIM]+[MMP]− in the spinning dope and subsequent fiber formation in a dry–wet-spinning process. The thus obtained precursor fibers were carbonized at different temperatures. In order to receive carbon fibers in high carbonization yields, the degree of substitution (DS) was adjusted. The rheological behavior of the spinning dope was studied and the spinning and carbonization parameters were optimized. Moreover, the precursor fiber tensile and structural properties were compared to pure cellulose fibers. According to thermal analysis coupled with evolved gas analysis (TGA-EGA) of the derivative and pure cellulose fibers, the carbonization yields could be almost doubled via the applied functionalization of cellulose and differences in the relative amounts of released gases during carbonization were studied. Both, precursor and carbon fibers were analyzed by, wide-angle X-ray scattering (WAXS), Raman spectroscopy, scanning electron microscopy (SEM), and tensile testing.