Influence of the glycol on the product structure during the wood liquefaction

The object of our work was the determination of the liquefying agent influence to the final lignin-based polymer structure formed during the wood liquefaction. For this purpose a comprehensive lignin-based polymer characterization was performed using quantitative 31P and 13C NMR (Nuclear Magnetic Resonance) and size-exclusion chromatography. Liquefied wood samples for analysis were prepared using a specific isolation procedure which enabled the separation of the high-molecular mass material (lignin-based polymer LBP) from the low-molecular mass products in glycol fraction. It was determined, that the final lignin-based polymer is produced by the predominant condensation reactions between the phenolic lignin subunits followed by the incorporation of the aliphatic liquefying agent moieties. As result, hydroxyl group content, aliphatic carbon and aromatic unit content in lignin-based polymer as well as molecular mass were found to be dependant on the type of the used polyhydric alcohol.