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Title
Effect of bamboo age on the pulping properties of Bambusa stenostachya Hackel
Authors
FENG-JYI CHANG EUGENE I-CHEN WANG YUAN-SHING PERNG and CHAO-CHUN CHEN
Received
December 4, 2011
Published
Volume 47 Issue 3-4 March-April
Keywords
Bambusa stenostachya Hackel, bamboo age, kraft pulping, soda pulping, hypochlorite bleaching, physical
properties
Abstract
This study investigated the effects of stem age of thorny bamboo (Bambusa stenostachya) on the results of different
cooking methods, conditions, bleaching conditions, and handsheet properties. The stems of 0.2-, 1.2- and 3-year-old
thorny bamboo were separately cooked by kraft and soda processes. The resulting pulps were then subjected to a
single-stage hypochlorite bleaching. The unbleached and bleached pulps were beaten with PFI mill to 400 mL CSF,
formed into handsheets and then compared as to their properties. Chemical analyses indicated that lignin content
increased with increasing bamboo age, while holocellulose and pentosans showed a contrary trend. The results of kraft
and soda cooking indicated that mature (3-year-old) bamboo was difficult to digest. Although pulp yields were fairly
high (55%), a substantial portion (22.4%) consisted in shives and coarse materials. At identical chemical charges, the
mature stems produced pulp with higher kappa number (28.2) than that of the youngest stems (22.9). The bleaching
results indicated that young, tender stems produced pulps with better brightness gains, and also the bleached pulps had
lower kappa numbers. At a hypochlorite charge of 10%, pulps from the young bamboo stems reached a brightness of
74% ISO. The pulps from mature stems, however, barely reached a brightness of 55% ISO. As to pulp handsheet
strength properties, the pulps made from young stems retained the best properties. Pups from mature bamboo stems
were more difficult to bleach and if more severe bleaching conditions were applied, the pulp strength properties
suffered a higher extent of degradation. Therefore, to garner benefits of both brightness and strengths, only younger
than 1-year-old bamboo stems should be used for pulping and papermaking, as they have both adequate strengths and
brightness needed for fine paper.
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