Synthesis and Characterization of Epoxy Thermosetting Polymers from Glycidylated Organosolv Lignin and Bisphenol A

Diglycidylether of bisphenol A and isophorone diamine (IPDA) are industrially used for polyepoxide curing. Herein, glycidylated Organosolv lignin (GOL) is cured with diglycidyl ether of bisphenol A and IPDA for intensive studies. Organosolv lignin (OL) is therefore first glycidylated with epichlorohydrin to a material with an epoxy content of 3.2 mmol g–1 and analyzed via FT‐IR, 1H and 31P NMR. Epoxy thermosets with up to 42 wt% GOL are cured in differential scanning calorimetry (DSC) crucibles, analyzing the residual reaction heat. Characterization of dog bone shaped specimens is described with regard to structural properties from scanning electron microscopy and FT‐IR, thermal properties by DSC and thermogravimetric analysis, as well as mechanical properties by dynamic mechanical analysis and stress/strain measurements. A lignin content between 8% and 33% leads to higher crosslinking density, resulting in a higher glass transition, lower swelling percentage, and increased stiffness (Young's modulus) if compared to non‐GOL polymers.