The use of lignin as a precursor to carbon fiber

This animation illustrates the use of lignin as a precursor to carbon fiber. A sustainable, renewable resource, lignin is derived from woody plants such as trees and switchgrass.
Lignin is the glue that binds a tree's cell walls together...and it comprises up to 30 percent of a tree's mass.
After harvesting, the tree is transported to a chip mill for conversion to wood chips for use as a feedstock by either a bio-refinery or pulp and paper mill.
At the bio-refinery, lignin is dissolved away from the cellulose into black liquor, and ethanol is produced from the cellulose contained in the wood chips.
At the pulp mill, lignin is also dissolved away from the cellulose into black liquor, and the cellulose in the wood is used primarily for production of paper but also chemicals.
In both cases, the lignin is precipitated out of the black liquor.
It is washed...then undergoes a drying process.
Next it is extruded...and pelletized.
The pellets can be packaged and shipped to another production facility or they can continue to the next step as illustrated here, where the pellets are fed into a melt extruder.
The combination of heat and pressure melts the pellets.
The molten lignin feeds into a metering pump...then through an extrusion die creating very fine filaments that solidify and are wound onto a spool.
The combination of extrusion die hole diameter and winding speed determines the final diameter of the lignin filaments.