STUDY OF THE RELATIONSHIP BETWEEN PULPING CONDITIONS AND THE PHYSICAL-MECHANICAL PROPERTIES OF PAPER

The aim of this study was to evaluate the influence of the pulping condition on the physical-mechanical properties of the eucalyptus bleached paper. Wood chips from a seven-year-old clonal hybrid of eucalyptus were used (Eucalyptus grandis x Eucalyptus urophylla). The pulps were obtained from two distinct Lo-Solids (TM) pulping conditions, namely: Condition PI - 16.5 % effective alkali, 30 % sulfidity, and 155 degrees C cooking temperature; and Condition PII - 17.5 % effective alkali, 32 % sulfidity, and 147 degrees C cooking temperature. Both conditions were performed to kappa number 18.0 +/- 0.5. The bleaching were performed following the bleaching sequences OA(Ze)DP to achieve 90 +/- 1% ISO brightness. The refinings were made at 0, 750, 1,500 and 3,000 revolution levels and the correlations were made based on the tensile index as independent variable of the refining curves. The physical-mechanical properties of the paper was influenced by the pulping conditions, with increasing of drainability, apparent density, TEA index, stretching and tear index to the PI pulp, considering the same tensile index. The PII pulp, however, achieved the same tensile index of PI pulp with lower refining level, thus, with lower energy waste. The pulping condition PII was most suitable for paper production for preserving more the integrity of the fibers, achieving the same tensile index with a lower refining level.