A CP/MAS C-13 NMR-STUDY OF RESIDUAL LIGNIN STRUCTURE IN AUTOHYDROLYSIS-EXPLODED WOODS AND BAGASSE

Structural breakdown of the lignin in autohydrolysis-exploded Pinus radiata and Eucalyptus regnans wood and in sugarcane bagasse has been examined using cross polarization magic angle spinning (CP/MAS) **1**3C NMR spectroscopy. The alkali- and acetone-insoluble (i. e. residual) lignins have undergone substantial cleavage of the major ( beta -0-4) interunit linkage and are most likely mixtures of partly depolymerized and repolymerized lignin fragments. Correlations between residual lignin structure, breakdown of the lignocellulose structure and enzymatic digestibility of the cellulosic carbohydrate are proposed.