Utilization of lignin for the production of fuels, chemicals and materials comprises one of the most interesting and challenging fields in biomass valorization.  Fast (catalytic) pyrolysis, gasification, oxidative/reductive depolymerization and hydrogenolysis are probably the most studied topics, focusing mainly at the production of high-added value monomers, i.e. oxygenated and/or alkylated phenolics, aromatics (BTX and naphthalenes) and alkanes. On the other hand, lignin functionalization (down-stream or in situ during biomass fractionation) is also important for the development of new bio-based polymers mainly via copolymerization of lignin with synthetic polymers or formation of various blends. Still, however, chemical functionalization of lignin with various groups such as alkyl, alkoxy, ester, etc. is not always straightforward and efficient, adding one extra process step in the overall “lignin biorefinig” schemes.  To this end, our group has conducted a systematic study of using kraft and organosolv lignin directly either as additive (filler) of classical epoxy resins (i.e. diglycidyl ether of bisphenol A- DGEBA) or as copolymerizing agent replacing completely or partly the diamine curing agents (i.e. polyoxypropylene diamines, isophorone diamine, etc.) taking into account lignin’s inherent functionality owing to the surface hydroxyl groups. The commercial softwood (spruce) kraft lignin showed low interaction and miscibility with the epoxy polymer. When the amine curing agent was of aromatic nature (i.e. DDS, DDM) then the interaction was significantly improved and epoxy – kraft lignin composites  with acceptable mechanical properties were produced. On the other hand, the organosolv lignin, acted as a very effective reinforcing agent of both rubbery (sub-ambient Tg) and glassy (Tg ~ 70-200<sup>o</sup>C) epoxy polymers using a wide range of aliphatic or aromatic curing agents, at relatively low addition levels of ca. 3-6 wt.% lignin. Both tensile strength and elasticity of the pristine epoxy polymers were improved at levels similar to those obtained by the use of more conventional nanofillers such as organoclays and CNTs.

Organosolv lignin as epoxy polymer reinforcing agent

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.