Chemical and physical characteristics of cellulosic materials obtained from kenaf (Hibiscus cannabinus L.) plants of different ages

The chemical and physical characteristics of kenaf plants (Zhejiang No. l cultivar from China) grown in Japan, 1996 and their cellulosic materials of different plant ages were investigated, and their bast (outer bark) was compared with their inner core. The ash content of the bast and the core of the kenaf plant of different ages decreased with the plant aged, however, the percent of the holocellulose content for the bast and the core of the kenaf plants at different ages was almost constant, similar to the kenaf plants gown in U.S.A., though its weight was different. The alpha-cellulose content, the sorption of basic dye, the degree of polymerization and the birefringence for the bast pulp fibers were higher than those for the core pulp fibers, however, the content of lignin, hot water extract, 1% NaOH solution extract and carboxyl group for the bast fibers was lower than that for the core fibers. The content of the hot water extract and 1% NaOH solution extract for the bast and core fibers increased with plant ages. However, there were only slight effects of the kenaf plant ages and the differences between the bast and the core fibers on the moisture content, the sorption of direct dye, the crystallinity, the crystallite size and the orientation. Therefore, these results indicate that kenaf (Zhejiang No.1) can be harvested at about 140-150 days in Japan.