Abstract
Abstract The spin–lattice relaxation times (T1) of the twelve most abundant carbon atoms in acetylated milled wood lignin (MWL) from hazelnut (Corylus avellanus) have been determined by the progressive saturation pulse Fourier transform (PSFT) technique. T1 values below 0.5 s have been found for the aliphatic carbon atoms in the C3 side chains, while substituted aromatic, carbonyl and CH3 carbon atoms in methoxy and acetyl groups have T values ranging between 1 and 3 a. From these results a quantitative determination of interunit linkages in lignin may be possible from car-bon-13 spectra with pulse interval times of at least 3 s. Furthermore, the carbon-13 NPIR spectra of three acetylated hardwood It MWLs, from black alder, hazelnut and mountain maple, have been recorded at 90.7 MHz. Five interunit linkages, β-0-4, α, β–bis-0-4, β-1, β-β and β-5, have been traced in each lignin and their frequences qualitatively compared with each other.
Published Version
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