Synthesis and thermal properties of ester-type crosslinked epoxy resins derived from lignosulfonate and glycerol

Among various biomass-based components, both lignin and glycerol are important, since they are abundantly produced as by-products in industrial processes. Accordingly, in the present study, new types of crosslinked epoxy resins were synthesized from lignin and glycerol. Polymers derived from two types of lignin-based crosslinked epoxy resins were prepared through two-step reactions, ester-carboxylic acid derivative preparation followed by crosslinked epoxy resin preparation, in order to establish a crosslinked epoxy resin system in which glycerol units were included. The resins obtained were labeled as follows: series 1, lignosulfonate-glycerol polyacid (Ser1LSGLYPA); and series 2, glycerol diglycidyl ether (Ser2GLYDGE). The functional groups of the resins were analyzed using Fourier transform infrared spectrometry. The thermal properties of the resins were analyzed using differential scanning calorimetry and thermogravimetry. The glass transition temperature of the crosslinked epoxy resins increased with increasing LSGLYPA and GLYDGE contents for Ser1LSGLYPA and Ser2GLYDGE, respectively. The thermal degradation temperature for Ser1LSGLYPA and Ser2GLYDGE did not show significant change, suggesting that the crosslinked epoxy resins were thermally stable. The mass residue at 500 degrees C was not affected by the changes of LSGLYPA and GLYDGE contents. (C) 2009 Society of Chemical Industry