Abstract
Lignin is an attractive biomaterial to replace petroleum aromatics due to its intrinsic aromatic structure and availability. In Thailand, the sugar industry has potential as a source of around 7.5 million tons of lignin per annum. Sugarcane bagasse lignin was developed as a low-cost precursor in carbon fiber production to replace polyacrylonitrile, a petroleum-derived polymer using the electrospinning technique. A technical study and financial assessment of carbon fiber production feasibility from bagasse lignin at the laboratory scale were performed in parallel, and the Thai carbon fiber market was surveyed. Results showed that electrospun carbon nanofiber could be produced from a mixture of 25% lignin and 75% polyacrylonitrile with diameter of 171 nm. The surface area of carbon nanofiber produced from lignin-polyacrylonitrile mixture was higher than that of pure polyacrylonitrile. However, increasing lignin content in the mixture resulted in lower conductivity. Lignin-polyacrylonitrile carbon nanofiber obtained was appropriate for those where higher surface area was required rather than structural application. A market survey indicated increasing exploitation of carbon fiber in Thailand during the last 5 years even though there was no industrial production of carbon fiber due to technical and financial constraints. Both carbon nanofiber and lignin production costs at laboratory scale (12.4 $/g) were 27 times lower compared to commercial carbon nanofiber (343.4 $/g) available in a similar form. This price difference presents an opportunity to further development of carbon nanofiber for industrial application, although intensive research and development are still required.
