Characteristics of Kraft pine pulps with different degrees of delignification

A comparison was made of the fractional composition and properties of two kraft pine pulps (conventional and 'hard) which differed considerably in their levels of delignification. Several methods of analysis, namely with the MorFi apparatus, optical microscopy in vision mode, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (WAXS) were used. It was shown that the fibres of 'hard' pulp (kappa number 68) show less damage, greater length and width, a higher mass per unit length (coarseness) and are more resistant to transversal deformation in comparison to the conventional pulp (kappa number 28). From the results obtained, it follows that 'hard' pulps are the fibrous semi-product which is better designed for oxygen delignification than are pulps produced in the conventional way.