The conversion of lignin into valuable products has attracted the interest of researchers. A series of modified polyurethane adhesives were prepared by blending corn straw enzymatic hydrolyzed lignin with polyester polyol and tolylene-2,4-diisocyanate. Mechanical properties, chemical structures, and thermal stability of the adhesives were characterized by mechanical properties tests, Fourier transform infrared spectrometry (FTIR), and thermogravimetric analysis (TGA). The results of shear strength test under room temperature and high temperature showed that the shear strength for modified polyurethane adhesives was improved by introduction of lignin. The introduction of lignin also improved the heat resistance of polyurethane adhesive. The TGA analysis results showed there were two stages in the thermal decomposition of the lignin blend modified polyurethane adhesive, and the maximum decomposition temperature of the first stage increased with the increase of lignin content, while the maximum decomposition temperature of the second stage decreased with the increase of lignin content. The TGA-FTIR combination analysis studied the main gas generated in the two decomposition stage’s peak times, of which CO2 was produced in the first stage, and CH4 was created in the second stage, indicating that the molecular chain fracture process of the two kinds of adhesives was similar in the whole decomposition process.

Corn stalk enzymatically hydrolyzed lignin (EHL) was used to modify bisphenol A-type epoxy resin. The curing reaction processes of the epoxy resin/polyamine blends and the lignin/epoxy resin/polyamine blends were studied via isothermal differential scanning calorimetry (DSC), and the effect of enzymatically hydrolyzed lignin on the curing reaction of epoxy resin was also analyzed. The results showed that the curing kinetics for two blends were not in full compliance with the autocatalytic curing kinetic model, especially the lignin/epoxy resin/polyamine blends. The apparent activation energy of the epoxy resin/polyamine blends increased with the increased presence of the lignin. The presence of enzymatically hydrolyzed lignin was beneficial to the curing process of epoxy resin/polyamine blends at high temperatures. The addition of the lignin increased the final curing reaction conversion rate, improved the glass transition temperature (Tg) and increased the bending strength for the epoxy resin/polyamine blends. However, the impact strength decreased in this process.