Fractionation of CIMV wheat straw lignin as an approach for promoting it interaction with isocyanates and characteristic of products obtained

The reactivity of CIMV lignin fractions with MDI has been investigated in extra dry dioxane (DOX) in argon atmosphere at 25 degrees of Celsius, using FTIR spectroscopy (absorbance band at 2273 cm^-1) for monitoring the NCO group disappearance during reaction. Five CIMV lignin fractions were obtained and investigated: 2 fractions obtained by separate extractions with DOX and methanol and 3 fractions obtained in the process of sequential extraction of CIMV lignin with dichloromethane, methanol and methanol/dichloromethane mixture. The highest second rate constants was detected for both methanol soluble lignin fractions