Three microcrystalline cellulose (MCC) samples were manufactured from bleached and unbleached softwood kraft pulp, and their properties were compared to those of the commercial MCC, Avicel PH-101. One of the produced samples retained a large portion of lignin (10.3%), while the two others retained only some. The physical, chemical, thermogravimetric, and molecular properties were analyzed. The presence of lignin caused a substantial effect on the thermogravimetric and chemical properties of the MCC, as well as on its surface characteristics. The lignin-containing sample degraded at lower temperatures, and its UV Raman spectra had a high intensity aromatic band (1600 cm-1) arising from the lignin. X-ray photoelectron spectroscopy confirmed a high surface lignin coverage (40%) in this specimen only. Particle size and BET surface area measurement results varied in some limits between MCCs, while the cellulose crystallinity index showed almost equal values between 0.82 and 0.84. This work introduces a new wood-based product, the lignin-containing MCC, comparable in properties to the wide-marketed Avicel.

Keywords: Microcrystalline cellulose; Lignin content; Cellulose characteristics; UV Raman; XPS