In this paper, prehydrolysis was used as the first treatment of poplar slab for producing high-grade dissolving pulp, the optimum prehydrolysis conditions of poplar were obtained as followings: liquid ratio 1:6, H_2SO_4 1.0%, the highest temperature of 160±5°C, heating time of 90min, holding time of 120min. Hydrolyzed poplar slab was cooked to determine the effects of various alkali charges on pentosans, alpha-cellulose, kappa number, and degree of polymerization(DP). The optimum cooking process conditions of poplar were obtained as followings: alkali dosage 24%, sulfidity 5%, the highest temperature of 160±5°C, heating time of 60min, holding time of 120min. Cooked pulps were bleached using Op-Q-P sequence. As a consequence, the poplar slab dissolving pulp of pentosan 3.73%, alpha-cellulose 95.13%, kappa number1.58, brightness 86.4%ISO, degree of polymerization (DP) 488.84 was obtained in our laboratory.
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