Effects of different bleaching conditions on the bending characteristics of two rattan species (Calamus merrillii Becc. and C. caesius Blume)

Scraped poles of Sika (Calamus caesius Blume), a small diameter rattan species, and Palasan (C. merrillii Becc.), a large diameter species, were subjected to bending tests following bleaching under varying conditions, air drying and steaming variables during the bleaching treatment included the bleaching agents, duration of soaking and temperature using a 3 by 3 by 3 factorial in a completely randomized design (CRD) experiment. Following bending, specimens were taken from poles that readily failed during bending as well as from those that did not exhibit rupture in the smallest possible jig. These were designated respectively as the samples that responded most adversely, and is most favorably to bleaching treatment. Statistical analysis showed significant differences in the bending behavior of unbleached sika poles compared with the bleached samples. For sika, the bleaching agent used and duration of soaking could account for these dif ferences. In palasan, bending properties were affected by bleaching agent used but not by the duration of soaking nor the temperature employed. The interactions between bleaching solution, duration of soaking and temperature was not significant in sika, while the interactions among these three factors was shown to significantly influence the bending characteristics of palasan. Results of proximate chemical analysis and anatomical studies done showed that bleaching had a significant effect on the chemical composition of both sika and palasan. Moisture content, ash, hot water extractives, and 1% NaOH soluble extractives were higher in bleached than unbleached sika, but lignin content was lower. In palasan, moisture content, ash, hot water extractives, 1% NaOH solubles and lignin content were higher in the bleached samples. No significant changes in the alcohol-cyclohexane extractives content of both sika and palasan were noted. Holocellulose content for both species was reduc e d by bleaching and can be correlated with the reduction in the flexibility of the poles. Fiber measurements revealed that fiber dimensions of sika were not affected by bleaching. However, among the fiber parameters of palasan, it appeared that the fiber length was affected by bleaching.