(252d) Influence of Industrial Fractionation Methods on Lignin Structure
Herein, eight widely used analytical techniques were used to characterize the structures of eight industrial lignin samples from wood to determine the effects different industrial fractionation and extraction methods have on the purified lignin stream. The scope of characterization covers hardwood and softwood lignin extracted using Kraft, super-critical water, and organosolv fractionation processes. Molecular weights were determined through gel permeation chromatography (GPC). Nuclear magnetic resonance (NMR) spectroscopy and infrared spectroscopy were used to identify common linkages, prevalence of various monolignol units, and functional moieties. Thermogravimetric analysis (TGA) provided insight to the thermal-physio properties of the lignin polymer. Extensive characterization of the lignin allows for correlations between the fractionation and extraction methods and final lignin structure, as well as, a comparison between the utility of the many characterization techniques. The non-Kraft lignin samples, in general, show lower levels of recalcitrance compared to the Kraft lignin, but still exhibit significant alteration to the original structures.