Effect of Using Whole Treefrom Three Hardwood Species Growing in Khartoum Stateand Pulp Beating Time on Paper Quality

Abstract

There is no virgin pulp and paper industry in the Sudan, which uses wood fiber and fiber from non-wood sources, like agricultural residues. Most paper industries use re-cycled paper. The paper manufactured this way gets weaker and weaker with time. This investigation is an attempt to continue the search for new raw materials to widen the scope of raw material suitable for pulp and paper industry, including whole tree utilizationis one way of rationalizing the use of our wood resources.Material for this investigation consisted of chips from both stem wood and whole trees from three species growing in the Central Sudan. These included the following: Acacia seyal var. seyal(Talh).,Prospisjuliflora(Mesquite)and Conocarpus erectus(Saudi damas). Samples from whole tree chips, from each species were chemically analyzed using TAPPI standards. Fiber morphology was also determined for stem wood and branch wood separately for each of the three species. These measurements were made for macerated fibers, using stereological techniques for determining fiber length, while cross-sectional measurements were made using the Quant meter Image Analyzer equipped with a microscope in Giad Material Research laboratory. Stem wood chips and whole tree chips were cooked separately for each species using soda-anthraquinone (AQ) pulping. Pulp yield was determined. Pulping process and pulp preparations were also carried out according to different TAPPI standards, and so were pulp beating, handsheet formation and testing. Evaluation of paper quality produced from this investigation was based on three properties, namely: tensile index, burst index, and sheet bulk. The results of the chemical analysis for the three species, showed significant differences between the three species, Saudi damashad the highest value of cellulose content (54.25% ), was lawest in talh (46.87%).Mesquie had the highestlignin content (28.87%), was lawest in talh (25.48%). Ash was the highest in damas (3.69%) followed by talh(2.03%) and lastly mesquite (1.82%),1% NaOH, cold water, and hot water and ethanol extracts also showed significant differences between different species. Fiber dimensions for the different parts of the three species, Mesquite branch was the highest fiber diameter (10.13um), the lowest value was for Mesquite stem (6.48 um).Lumen diameter It ranged between the highest (7.74 µm) for mesquite branch,and the lowest value (4.48µm) for mesquite stem. The fiber ratios for the different parts of the three species: rankle ratio (RR) was the highest (0.59) for talh branch and the lowest value (0.30) for damas branch. Fiber flixability (FF) also showed significant differences between different parts of trees (P = 0.0313). The highest value was for damas branch (0.77),The lowest value was for talh branch (0.64).The pulp yields for the different parts of the trees.They ranged between 40.11% for talh stem to 39.61% for mesquite and 39.32 for damas. With regards to whole tree pulp yields again talh gave the highest yield (38.0%) compared to mesquite (37.83%) and damas (36.61%).The variation of sheet bulk of paper was the highest from talh stem (7.57cm³/g), was the lowest from Mesquite whole (5.857.57cm³/g).The tensile index of paper was t highest in damas stem (80.8Nm/g) after 8min beating time. Was the lowest for mesquite whole tree (50.6Nm/g) after 7min beating time. Also the burst index increased with increasing beating time, was highest in talh stem and damas stem (2.6kba*m2\g) after 8min beating time, waslawest for Mesquite whole tree (1.9kba*m2\g) after 7min beating time.