QUALITY OF REACTION WOOD IN EUCALYPTUS TREES TILTED BY WIND FOR PULP PRODUCTION

Abstract

This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by the action of winds, as well as to explain the pulping parameters due to the quality of the wood. The trees were grouped into four tilt ranges ranging from 0 to 50º, and the basic density, the chemical composition of wood, and the performance in the kraft pulping were assessed. Normal and tension wood had similar basic densities; as for the opposite wood, its density was lower, being responsible for the decrease of the reaction wood density. The chemical composition of the wood was influenced by the presence of reaction wood in the stem; tension and opposite wood showed lower levels of extractives and lignin and higher holocellulose content when compared to normal wood, with favorable wood quality for pulping. The increase in holocellulose content and the reduction of lignin and extractives content contributed positively to a more delignified pulp and reduction of the Kappa number. However, after cooking the reaction wood under the same conditions as those of normal wood, reaction wood pulping tends to have a lower purified yield.