Document Type : Research Paper
Authors
1 M.Sc., Department of Cellulose and Paper Engineering, Shahid Beheshti University, savadkooh, Zirab, Iran
2 Assistant Professor, Department of Cellulose and Paper Engineering, Shahid Beheshti University, savadkooh, Zirab, Iran
3 Assistant Professor Department of Cellulose and Paper Engineering, Shahid Beheshti University, savadkooh, Zirab, Iran
4 Associate Professor, Department of Wood and Paper Science, Sari University of Agriculture and Natural Resources Sciences, Sari, Iran,
Abstract
This research was carried out to compare the paper properties from rice straw applying sodium and potassium based Chemimechanical pulping processes. Cooking conditions in potassium based pulping were adjusted as; potassium sulfite 6, 8, 10 and 12%, potassium hydroxide 3, 4, 5, 6, 8 and 12% on oven dry weight of rice straw, impregnation time; 30 minutes, liquid to rice straw ratio of 7:1, cooking time 30 and 60 minutes and cooking temperature 130, 150, 160, 165 and 170 oC. In sodium- based pulping, cooking conditions were selected as; sodium sulfite 6 and 8%, sodium hydroxide 3 and 4 % on oven dry weight of rice straw, impregnation time 30 minutes, liquid to rice straw ratio of 7:1, cooking time 30 minutes and cooking temperature 130 and 150 oC. The selected treatment in potassium based pulping showed the average total yield of 65.19 and reject of 4.22% and in sodium based pulping showed the average total yield of 69.75 and reject percent of 3.68. After refining the selected pulp to reach the freeness of 300±25 ml CSF, 60 g/m2 hand sheets were made and physical, mechanical and optical properties were measured. Results showed that the tensile strength index, breaking length and apparent density of paper made from potassium based process was similar to paper made from sodium based process. The papers made from potassium based process had higher burst strength index and brightness compared to sodium based process and papers made from sodium based process had higher tear index and higher K/S values than potassium based paper.
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