Lignin as a base material for materials applications: Chemistry, application and economics

Lignin has long laboured under the label of “waste material”. However, as part of the thematic network EUROLIGNIN, a survey and desk study was undertaken to assess the changes and patterns in the utilisation of lignin with respect to materials applications. This showed that over the last 10–15 years there has been an explosion of research into, and commercialisation of, lignin-based products and processes which add significant value to a material that was previously, and continues to be, used as a low-value fuel for pulping boilers. The innate chemistry of lignin, a phenolic heteropolymer, has allowed it to make inroads into the high value polymer industries whilst continuing to act as feedstock material for the binder industries. Indeed the replacement of phenolics by lignin in resins systems is economically attractive with the phenolic resins market utilising approximately 2.52 M tonnes in 2001. Currently lignin, predominantly as lignosulphates, is used as a binding and dispersing agent in different industries with approximately 1 M tonnes (on a 100% solids basis) used annually, for example, in concrete admixtures. These and other applications will be discussed and expanded upon here with emphasis on both the economics of the markets and what is still required for lignin to mature as a valuable resource in its own right.