Determination of Kraft-NaBH4 pulping condition of uludag fir (Abies bornmuelleriana Mattf.) and brutia pine (Pinus brutia Ten.)

The aim of this study is to evaluate the effects of NaBH4 on pulp and paperproperties on conventional kraft pulping. The chemical composition of the Butia pineand Uludag fir woods were determined and these wood species were utilized as rawmaterials in pulping experiments.Two sets of pulping experiments were conducted in this study. In the first set,six conventional kraft cooks were made to determine the optimum conventional kraftcooking conditions by altering the cooking time and active alkali taking into accountthe kappa number and pulping yield. The obtained results indicated that the optimumkraft cooking condition was accomplished when kraft cook was made using 18%active alkali for a cooking period of 90min. at 170MC for both wood species.Cooking at that condition gave 46.3% and 47.1% screened yield, 28.5, and 27.4kappa number, and 1102cm3/g and 1014cm3/g viscosity for brutia pine and Uludagfir respectively. A second set of cooks were made taking into account theoptimum kraft cooking condition, and 1, 2, and 3% NaBH4 was added to the cookingdigester based on oven dry wood.The results showed a significant decrease in pulping rejects and increase inpulping yield when NaBH4 was added to the cooking digester. This finding indicatedhigher pulping selectivity of NaBH4 added kraft method. In addition, higher pulpviscosity and brightness was observed in NaBH4 added kraft method. On the otherhand, the strength properties obtained in Kraft-NaBH4 were a little lower comparedto the conventional kraft method.Keywords: Alkaline pulping, delignification, kappa number, kraft pulping,mechanical properties, brutia pine, uludag fire, sodium borohidrate,yield.