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 *Ain-Shams University, Cairo, EGYPT; **Kochi University, Japan

This paper explores the production of high viscosity pulp from kenaf bast by using three different treatment sequences (A, B and C). The chemical compositions (cellulose, hemicellulose and lignin contents) and viscosity from these treatments were determined. Yield and kappa number of sample B are the highest one, while sample A shows the highest viscosity or degree of polymerization rather than those from B and C samples. Furthermore, the pulp extracted from these treatments was investigated by vibration spectroscopy and the structure differences found were validated by X-ray diffractometry. The FT-IR spectra of all pulp samples reveal the same chain conformation but different in mean hydrogen bonding, relative ether linkage and crystallinity index. From X-ray diffractograms of extracted pulp, the crystallinity index percentages for A, B and C samples were 77.0, 73.4 and 75.0 that confirm the FT-IR results.     

Keyword: Crystallinity index, FT-IR spectroscopy, Kappa number, Kenaf, Viscosity, X-ray diffractometry.

(Lignin Symposium at Fukui-Japan, November 2003)

New applications of kenaf fiber have been developed not only in the pulp and paper industry, but also in other industries such as fiber board and nonwoven products. Kenaf fiber composites are increasingly used for making automotive interior trim parts because of their excellent strength and renewability. An application example is use of kenaf fiber in replacing glass fiber for making automotive headliner. Preparation of the fiber before it is used for composite reinforcement is important. With bast fibers, such as hemp, flax and kenaf, the fiber needs to be removed from the plant core (decortication) and extracted from the natural plant polymer (retting) before it can be used for composite manufacture. Pretreatments with some chemicals will increase the penetration and bonding efficiencies of the polymer matrix.

                Kenaf bast fiber from 58 varieties grown in Zhejiang province, China was treated using three treatments. First treatment used ammonium oxalate, sodium hydroxide and acidic chlorite (AT3), second treatment used ammonium oxalate and sodium hydroxide (AT0) and the third one was retting treatment. Some parameters such as diameter, height and weight of stalk, and also fiber strength were measured for screening method.

Treatment AT3 show  much better strength than the other two. It means the single fiber which belongs to AT3 is stronger than the bundle fiber of AT0 and retting treatments. Moreover the chemical treatment of AT0 has much stronger bundle fiber than retting one. The best-8 varieties (kenaf sample number 8, 11, 12, 30, 32, 48, 52 and 58) were selected based on the fiber strength. From the best-8 varieties, kenaf sample number 12 and 32 reached the superior two if evaluated with other factors.

(Annual Meeting of Japan Wood Research Society at Kyoto-Japan, March 2005)

Wiwin Suwinarti*, Yu Wang*, Zhou Cheng**and Kazuhiko Sameshima*

*Kochi University (Japan); ** Tongji University (Shanghai)

       In view of recent global environmental issues and inadequate raw fibre resources, scientists worldwide have begun to show interest in exploiting the full potential of kenaf (Hibiscus cannabinus L.) and its diverse uses.  New applications of kenaf have been developed not only in the pulp and paper industry, but also in other industries.  To develop a new usage of kenaf bast pulp, the pulp should be processed in optimum conditions, because it has been shown to be highly sensitive to the conditions under which wood pulping employed. A combination of ammonium oxalate pre-treatment, soda pulping under normal pressure and acidic chlorite treatment yielded an excellent pulp with extraordinarily high viscosity and highly desirable mechanical properties.  On the other hand, using a sequence of acidified sodium chlorite, ammonium oxalate and 1% sodium hydroxide treatment generated good quality kenaf bast pulp for fiber length measurement, but it exhibited rather lower viscosity.

       Kenaf bast fiber was treated by ammonium oxalate, sodium hydroxide and acidic chlorite at different order and conditions for each sequence. The viscosity of pulp and the paper strength properties were determined according to the TAPPI standard.

       The viscosity of the first sequence (Kenaf-A) was confirm to be higher than that of the second sequence (Kenaf-B). The other kraft pulps (pine, birch and commercial kenaf bast), showed lower viscosity. The similar result also appeared on the paper strength properties where Kenaf-A is the highest. The index of tensile, burst, tear and folding endurance of kenaf-A is 87.2Nm/g, 7.2kPa.m²/g, 8.1mN.m²/g and 771times, respectively and kenaf-B is 74.3 Nm/g, 6.5kPa.m²/g., 7.0 mN.m²/g and 490 times, respectively.

(Annual Meeting of Japan Wood Research Society at Sapporo-Japan, August 2004)

Wiwin Suwinarti and Kazuhiko Sameshima

Faculty of Agriculture, Kochi University, Japan

       The main objective of this research is to know the distribution of viscosity and fiber length along a stem height and the harvesting time difference. Kenaf bast fiber was treated by a sequence treatment of ammonium oxalate, sodium hydroxide and acidic sodium chlorite (A) and acidic sodium chlorite, ammonium oxalate and sodium hydroxide (B). The agronomic and pulp characteristics were examined. The result showed the viscosity and the fiber length was affected by the harvesting time. The sample of 153 days after seeding gave much higher viscosity but shorter fiber length than those of 80 and 116 days after seeding. The higher section has lower viscosity but longer fiber length. This study also confirmed that the method A is the best method for high viscosity bast pulp production while the method B is the best method for fiber length preservation.

Keywords: Kenaf bast fiber, harvesting time, stem height, viscosity, fiber length

(International Wood Science Symposium at Bali-Indonesia, August 2005)

Wiwin Suwinarti*, Yu Wang*, Zhou Cheng** and Kazuhiko Sameshima*

       The main objective of this research is to decide the optimum conditions of kenaf bast pulping for high pulp viscosity and paper strength properties.  Kenaf bast fiber was treated by ammonium oxalate, sodium hydroxide and acidic chlorite at different order and conditions in three methods, A, B and C. The viscosity of the pulp and the paper strength properties were determined according to the TAPPI standard method.

       Generally, the viscosity and the paper strength properties of Kenaf-A derived from the method A was the highest compared to the others. Comparison of the viscosity and the strength properties with other pulps (kenaf bast commercial and wood pulps) indicated all the three methods give higher results and the Kenaf-A is an optimum pulp so far.

(International Wood Science Symposium at Kyoto-Japan, September 2004)