3.1 Towards High-Yield, High-Strength Pulps via Oxygen Delignification
- Alvaro Castaneda
- PhD student,
- KTH
- Co-author(s):
- High‑yield pulps such as chemithermomechanical pulp (CTMP) and neutral sulfite semichemical pulp (NSSC) offer significant yield advantages over kraft pulps but are limited by lower tensile strength and reduced fibre bonding. Oxygen delignification has been proposed as a mild post‑treatment to enhance performance while maintaining high yield in traditional kraft pulp manufacturing, as oxygen delignification is more selective towards lignin removal than carbohydrate degradation. Yet how this treatment affects high‑yield pulps and the underlying structure-property mechanisms remain poorly understood. This study investigates the effects of oxygen delignification on the mechanical, chemical, and swelling properties of CTMP and NSSC pulps, using kraft pulp as a performance reference. Tensile and tear indices, water retention value (WRV), fibre charge, and yield were evaluated to describe bonding development and fibre behaviour. Preliminary results show that oxygen delignification increased fibre charge by more than 50–80 µeq/g and enhanced WRV, leading to tensile improvements in both pulps while preserving high yields. Together, these results suggest that swelling and surface oxidation were the primary drivers of bonding enhancement, with CTMP and NSSC exhibiting distinct responses. These results contribute to understanding how oxygen delignification repositions high‑yield pulps within the conventional yield–tensile strength trade‑off and provide a basis for designing optimized, yield-preserving treatments for high‑performance lignocellulosic fibres.
- Time of presentation: 9.00