Document Type : Research Paper
Authors
1 M.Sc., Wood and Paper Science, Tarbiat Modares University, Iran
2 Assistant Prof. Dept. of Wood and Paper Science and Technology, Gorgan University of Agricultural Science and Natural Resources, Iran
Abstract
Comparative study of pulp yield of sap wood and heart wood of Populus deltoides under both Kraft and soda cooking process have been showed that the heart wood pulp has a lower yield than that of sap wood pulp. Yield of heart wood and sap wood soda pulps was 4 percentages higher than Kraft pulp. Contrary to yield, residual lignin content (Kappa number) is more in heart wood pulp than sap wood pulp in both processes. Kappa numbers of heart wood and sap wood Kraft pulps were about 34% lower than soda pulps. The results showed that in spite of lower yield of heart wood than sap wood, the residual lignin of heart wood pulp was more than sap wood pulp. The higher delignification efficiency of Kraft cooking is related to cooking liquor compositions, especially Na2S
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