Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Quality improvement the properties of poplar high yield pulp

The quality of poplar high yield pulps, especially chemimechanical pulps (CMP) manufactured with alkaline peroxide impregnation can be improved by using an enzymic treatment based on manganese peroxidases The work performed covered a comparison of poplar clones, screening of Phanerochaete chrysosporium strains and improvement of the manganese peroxide activity. It was found that the 4 poplar clones selected for thermomechanical and alkaline peroxide mechanical pulping did not show the same response. Some clones were very promising for high yield pulping and could be developed for short rotation coppices. Raspalje poplar clone gave thermomechanical pulps (TMP) and CMPs with better pulp properties due to the fact that the fibres possess a gelatinous layer in the secondary layer. This layer, rich in polyose favoured fibrillation, fibre separation and the formation of hydrogen bonds during paper sheet formation. The classification of the clones, on the basis of suitability seems to be similar for both types of pulping process. The screening of different fungus strains to produce manganese peroxidases indicated that the strain Phanerochaete chrysosporium I 1512, had the best enzyme production. The effects of the various culture components were analysed and their effect on manganese peroxide activity determined. It was difficult to enhance production by changing the composition of the medium. Under optimized conditions, strain I 1512 produced the highest activity recorded, at more than 3500 units/l of manganese peroxide activity. Various manganese peroxide treatments were carried out on industrial pulps at different stages of the process. The pulp quality varied, depending on the lignin peroxidase presence and on the penetration of enzymes. This was estimated using lignin analysis, electron microscopy and immunocytochemical labelling and correlated with the pulp quality obtained after treatment.

Reported by

Centre Technique de l'Industrie des Papiers
Domaine Universitaire
38044 Grenoble
France
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