Analytical Pyrolysis as a Tool to Assess Residual Lignin Content and Structure in Maritime Pine High-Yield Pulp

The residual lignin content of unbleached maritime pine (Pinus pinaster Aiton) Kraft pulps was assessed by analytical pyrolysis (Py-lignin) and the results were compared to Klason kappa number. Thirty samples, each from an individual tree, delignified under identical conditions. varied widely as Py-lignin (5.9%–9.2%), (8.2–15.1), number (59–112). Despite a systematic difference between Klason, they strongly correlated (R2 = 0.90). H/G ratio pulp ranged 0.145 0.195, with mean 0.165, which is more than two times average Maritime wood (0.064). show that pulping, selectively degrades labile inter-unit links, changed pattern products considerably and, consequently, its structure. This shows enrichment in H-lignin-derived products, namely phenol, p-cresol, m-cresol, some G-lignin-derived such guaiacol 4-mthylguaiacol, decrease coniferylaldehyde, homovanillin, eugenol. Principal component analysis (PCA) G- are distributed along PC 1 based on their content. loadings plot this separation mainly due small G-lignin including 4-methyl guaiacol, 4-vinyl isoeugenol (trans), abundant higher obtained appropriate method for quantifying provide information regarding how degraded during pulping process.