Structure and thermo-chemical properties of continuous bundles of aligned and stretched electrospunpolyacrylonitrile precursor nanofibers collected in a flowing water bath

CARBON 50 (2012) 1262 – 1270

Jie Liu a, * ,Gui Chen a , Hui Gao a , Lifeng Zhang b , Sai Ma a , Jieying Liang a , Hao Fong b

Abstract

Continuous bundles of aligned and stretched electrospunpolyacrylonitrile (PAN) precursor nanofibers were prepared in an attempt to develop carbon nanofibers with superior strength. The bundles were prepared through collection of electrospun nanofibers with a flowing water bath followed by stretching in water at 97 C. Their morphologies, structures, and thermo-chemical properties were characterized by SEM, XRD, and DSC. The shrinkages in boiling water and the amounts of residual solvent were also measured. The results indicated that, the nanofibers in the bundles were uniform with **ooth surfaces and **all variations in diameters; after stretching the bundles by 4 times, the average fiber diameter was reduced to 56%, while the crystallinity of PAN was improved by 72%. The post-spinning stretching process facilitated the stabilization of PAN, as evidenced by the shift of the cyclization reaction to a lower temperature with **aller activation energy and larger enthalpy change. In comparison with the commonly adopted nanofiber collection method of a rotating drum, the flowing water bath method results in higher degree of uni-axial alignment and more desired structures of nanofibers.