Ian Dallmeyer
Frank Ko
John F. Kadla
LIgnin-based carbon fibres
Tue, 03/06/2012

Electrospinning is an effective strategy to produce micron and sub-micron
diameter fibrous networks from a variety of polymeric systems. Using seven different
technical lignins the effect of lignin structure on fiber formation by electrospinning
was studied. Surprisingly, none of the technical lignins could be electrospun into continuous
fibers, although beaded fiber formation was observed for the softwood Kraft
lignin system at high concentration (>50 wt%). However, the addition of poly(ethylene
oxide) dramatically affected the electrospinning behavior and fiber formation. For all
of the technical lignins a clear transition from electrospray or beaded fibers to uniform
fibers was observed upon addition of poly(ethylene oxide); the lignin concentration
dependent on poly(ethylene oxide) content. In all of the systems a linear increase in
fiber diameter with increasing lignin concentration was observed. At the same concentration,
the various lignin solutions had varying viscosities and different electrospinning
behavior, that is, fiber diameter and ability to form uniform fibers, suggesting lignin
specific structures and intermolecular interactions are influencing solution properties
and electrospinning behavior. In fact, specific viscosity versus concentration plots reveal
scaling exponents', η ~ c7.4-7.8 consistent with a branched polymer participating in
intermolecular interactions such as hydrogen bonding or association complexes.