Improved surface properties of CTMP fibers with enzymatic pretreatment of wood chips prior to refining

Surface properties of chemithermomechanical pulp (CTMP) fibers produced from enzymatically pretreated eucalyptus wood chips prior to refining were investigated by Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM) and X-ray Photoelectron Spectroscopy (XPS). The results showed that in a traditional CTMP refining process most fiber disruptions occur in the middle lamella (ML) leaving behind a significant amount of hydrophobic materials on the resulting fiber surface. However, in a Bio-CTMP refining process, fiber fractures preferentially take place in the primary (P) and secondary 1 (S1) layers or the S1 and secondary 2 (S2) layers, which results in more fibrillation being generated in the subsequent refining thus improving inter-fiber bonding strength and paper strength. XPS chemical composition analysis together with pulp physical strength property showed that the surfaces of Bio-CTMP fibers become enriched with a greater proportion of carbohydrates in comparison with CTMP fiber surface, which supports FE-SEM and TEM observations.