Kraft Pulping of Two Fast Growing Populus euramericana Clones

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Abstract

Based on the results of field experiments on poplar clones in Karaj, two fast-growing Clones of Populus euramericana i.e. P.e. vernirubensis & P.e. costanzo were selected for pulping investigation. Three trees from each clone at the age of 12 years were selected and samples were cut at the breast height. Average length, width and thickness of the chips showed no significant difference. Kraft pulping variables including five pulping times (15 to 75 min.) and two chemical charges (18 % AA at 23 % Sulfidity and 20 % AA at 25 % Sulfidity) were applied. The accepted yield, kappa number and rejects measurement of pulps showed that the optimal pulping condition is cooking time 45 min and AA 18% at 23% Sulfidity. The pulps from the two clones showed no significant difference in pulp beatability to target freeness of 400 ml CSF. Bauer McNett fiber classification test showed that P.e. costanzo provides higher fiber length and lower fines content. Statistical comparison of wood production, pulp and handsheet properties of the two clones indicated that P.e. costanzo is superior clone in burst strength index and average fiber length, whereas P.e. vernirubensis is more suitable in terms of growth rate and tear strength index. Significant differences were not observed between clones in other properties.

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