INFLUENCE OF WOOD STORAGE TIME IN THE PAPER PROPERTIES OF Eucalyptus globulus Maria Pereira 1 , Gabriel Sousa 2 and Ofélia Anjos 1,3,4 1 ESA/IPCB – Escola Superior Agrária – Instituto Politécnico de Castelo Branco 2 RAIZ – Research Centre of Forestry and Paper (grupo Portucel Soporcel) 3 CERNAS – Research Centre of natural resources studies environmental a society 4 CEF – Forestry research centre, Instituto Superior de Agronomia ABSTRACT In this work we studied the effect of moisture and chip pile storage time of Eucalyptus globulus wood, regarding the impact in kraft cooking and papermaking. Experimentally, chip samples were collected with different storage times (0, 15, 30, 60 and 90 days) from two distinct piles (wet and dry). The cooked chips after disintegration, screening and washing were submitted to a bleaching stage, in ECF sequence following five stages (D 0 E 1 D 1 E 2 D 2 ). The pulps were beaten in a PFI mill at 1000, 2000 and 3000 revolutions. For the cooking results we observed higher yield and lower alkali consumption for the wet pile chips and lower storage time (15 days). The results showed that storage time is a significant factor (ANOVA results) for almost paper properties studied and influenced mainly the internal fibre links. For what paper properties are concerned, the difference between piles isn’t so evident, the major differences are observed for the lower storage time (15 days). Keywords: Eucalyptus globulus, wood moisture, Kraft process, storage time. INTRODUCTION In Portugal wood is one of the main cost inducing factors on the pulp and paper industry. Therefore, is desirable that wood should be efficiently processed. This includes all wood yard process operations, especially woodchip pile storage management. Woodchip pile storage has both harmful and beneficial effects over kraft pulping process. It reduces pitch formation potential (Freire, 2003), which hinders pulp quality and generates equipment deposits. It also eliminates wood’s low molecular components that would inevitably consume cooking alkali. On the other hand, severe woodchip pile storage conditions can promote an extensive cellulosic material degradation resulting in a pulp yield loss. In addition to this, pulp quality can also be affected, namely bleached pulp’s beatability. Woodchip pile moisture and temperature, along with storage time, are probably the main factors influencing woodchip quality and thus kraft process itself. Outside chip pile storage is inevitably affected by climate variations, inducing seasonal moisture and temperature variations. Therefore in this project we studied the effect of moisture and chip pile storage time of Eucalyptus globulus wood, regarding the impact in kraft cooking and papermaking properties. MATERIAL AND METHODS Eucalyptus globulus chip samples were collected from two different pilot piles (wet and dry) with different storage times (0, 15, 30, 60 and 90 days). The chips samples were cooked with the following reaction conditions: AA=16-17% (as Na2O) for constant kappa number; sulfidity =28%; liquor/wood ratio=4/1; initial temperature = 40ºC; time to temperature = 120 min; time at temperature (160 ºC) = 60 min. Cooked chips were thereafter disintegrated, screened and washed: After cooking, pulps were submitted to an ECF bleaching sequence (D 0 E 1 D 1 E 2 D 2 ) until 90% of brightness is reached. Bleached pulps were beaten in a PFI mill at 1000, 2000 and 3000 revolutions, and laboratory paper sheets were produced, including the unbeaten pulps, which made 4 samples per storage time and for each moisture piles. Some mechanical and optical properties and the correspondent suspension fibre characteristics were determined.