2003•Fibres and Textiles in Eastern EuropeRequires access
Characteristics of Kraft Pine Pulps with Different Degrees of Delignification
Barbara Surma-Ślusarska, Dariusz Danielewicz
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Abstract
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. Se veral 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. terrupt pulping at a higher kappa number (>40) followed by oxygen delignification has been noted [1]. This solution aims at better utilisation of the oxygen effect on lignin in order to shorten the kraft pulping and maintain the strength potential of the wood fibres and the high pulp yield to as great an extent as possible. At the Institute of Papermaking and Printing, the modified sulphate-pulping technology for both softwood and hardwood was devised. This paper presents the comparative characteristics of conventional kraft pine pulp fibres (with a kappa number of about 30) and high-yield kraft pine pulp fibres (with a kappa number of about 70) destined for two-stage oxygen delignifi cation. Conventional microscopic photographs show the changes in pulp fibres resulting from the pulping process. When necessary to show details which are diffi cult or even impossible to perceive in visible light, the SEM and AFM techniques are used. Thanks to much higher magnification, these methods allow all changes taking place to be detected. Fractional composition and fibre morphology were analysed with the use of the MorFi apparatus from Techpap (France) [2].