WOOD RESEARCH Volume 70, Number 2, 2025
GANIS LUKMANDARU, MUHAMMAD AKBAR FAQIH, and SIGIT SUNARTA

PULPING AND PAPERMAKING POTENTIAL OF ACACIA AULACOCARPA BENTH WOOD IN INDONESIA

In this study, samples from 27-year-old Acacia aulacocarpa grown on a plantation were examined to determine suitable kraft pulping conditions and properties for paper production. The results showed that A. aulacocarpa had a high basic density of 0.65 g/cm3 and a short fiber length of 0.84 mm. The derived values for Runkel, slenderness, and flexibility ratios were 1.02, 53.01, and 0.48, respectively. Five different active alkali concentrations ranging from 14% to 22%, with intervals of 2% were applied for kraft cooking. The percentages of reject, kappa number, and residual active alkali of black liquor were negatively related to the charge applied in pulping runs. Pulping with 18% active alkali content obtained a screened yield of 51.4% at a kappa number of 34.1. The 20% active alkali cook had the highest mechanical properties of the handsheets. The burst and tear indices met the Indonesian National Standard for leaf (hardwood) bleached kraft

WOOD RESEARCH Volume 65, Number 4, 2020
Ehsan Yousefi, Mohammadreza Dehghani Firoozabadi, Omid Ghaffarzadeh, and Kuňa Vladimír

Investigation of urea usage in soda pulping of Populus deltoides

In this study, the use of the urea was investigated as an additive in soda pulping of Populus deltoides in comparison with the conventional soda and Kraft processes. Urea was used at the ratios of 1.5%, 3%, 4.5%, and, 6% based on the dry weight of wood in the soda process. The constant factors were determined for each distinct cooking of soda, soda-urea, and Kraft treatments. The dry weight of the chips was 150 g, the ratio of the liquor to wood (L/W) 4: 1, the maximum temperature 170°C and active alkaline content 18% (based on Na2O). Cooking time, the only changing factor, was varied from 30 to 330 min depending on the type of cooking. Besides, the sulfidity ratio was 25% for all Kraft treatments. After ending pulping time, the pulp samples were fully washed. Then, the screen accepts and the screen rejects were evaluated using a 20 and a 200-mesh screen. The observation shows that the more urea usage is in a pulping liquor, the more total yield, however, the screen reject value unexpectedly increased. Hence, the optimum values were determined by 1.5% and 3%. The investigation of handsheet samples indicated an increment trend of mechanical strengths with an addition of urea; so that the tear, tensile, and burst indexes of soda-urea samples were significantly higher than for each symmetric soda sample. It has been supposed that cellulose carbamate is essential in the enhancement.