AGE EFFECT ON KRAFT PULPING OF GAMAR (Gmelina arborea Roxb.)

Use of short rotation species for pulp production is one of the methods to meet the demand of pulpwood in the pulp mill. In this research pulp making characteristics of gamar of five age groups have been studied with respect to yield and quality pulp to reduce the harvesting time of the species. Chemical component of five age group of gamar have been measured and the amount of hemi cellulose, cellulose, lignin, extractive and 1% caustric solubility are (27.53-29.19), (42.1-44.97), (23.5-24.53), (3.00-3.30) and (17.00-14.50), respectively.  Pulps have been prepared from Gamar (Gmliina arborea, Roxb) at ages of 4, 6, 8, 10 and 12 years with kaft process. Cooks were made with at active alkali doses 16, 18, 20% and maintaining sulfidity 25% at 170°C. Pulp-yield varied from 48.7 to 53.1 percent at various ages for gamar. The best pulp, bleachable grade pulp, was obtained with 8 years old gamar wood with pulp yield at 20 percent active alkali and 25 percent sulfidity under optimum condition.  The fiber length also increased with increased of ages. The hand sheet was made and the the physical strength properties likely tear, tensile and burst were evaluated at 450 and 250 Canadian Standard Freeness (CSF). The physical strength and other properties of gamar kraft pulp the best compared favorably with those of other hardwood pulps are widely used in the world. The strength properties of 4 and 6years pulp showed low tear strength. With the increased of age of gamar tear, burst and tensile strength are increased. The pulp produced from 8 years and onward possessed moderate strength properties. Considering pulp yield and quality the optimum cutting cycle of the gamar would be eight years.