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

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

    Kenaf bast fiber was treated successively by ammonium oxalate, sodium hydroxide and sodium chlorite at different order and conditions in three methods, A, B and C　(Table 1). The characteristics of  pulp and paper were determined by various methods including TAPPI test methods.　The Kenaf-B, derived from the method B, showed the longest fiber length as length weighted average which confirmed that this treatment is the best preparation method for fiber length measurement. However, the viscosity and the paper strength properties of Kenaf-A was the highest if compared to the other two methods. Comparison of the viscosity and the strength properties with other pulps (commercial kenaf bast and wood pulps) indicated that all the three methods have superior properties but the Kenaf-A is the best pulp so far.

Keywords: kenaf, bast fiber, viscosity, fiber length, paper strength

(Japan TAPPI Journal, June 2005)

 *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)

Wiwin Suwinarti and Kazuhiko Sameshima

Faculty of Agriculture, Kochi University (Japan)

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

(Japan TAPPI Journal, In Press)

Sherif Keshk*, Wiwin Suwinarti** and Kazuhiko Sameshima**

       The high viscosity kenaf bast pulps were prepared by using three different methods (A, B and C) and their viscosity values were 109, 63 and 102 cP, respectively. The physical structures of these samples were characterized by FT-IR spectroscopy, X-ray diffractmetry and CP/MAS ¹³C NMR spectroscopy. Although the FT-IR spectra of all pulp samples revealed the similar chain conformation, the magnitude order of mean hydrogen bonding, relative ether linkage and crystallinity index were in the same trend with the order of viscosity values. X-ray diffractograms and CP/MAS ¹³C NMR spectra indicated the presence of residual lignin between the (1`10) plane of the pulp that subjected to the method B. However, FT-IR, X-ray and CP/MAS ¹³C NMR analyses showed the method A gives the highest crystallinity pulp. Furthermore, the relationships between viscosity and crystallinity index values in these three methods were in a high correlation (R>0.9), that indicates the viscosity is parallel to the crsytallinity.

Keywords: CP/MAS ¹³C NMR spectroscopy, crsytallinity index, FT-IR spectroscopy, kenaf bast fiber, viscosity, X-ray diffractometry.

(Japan TAPPI Journal, In Press)

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

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

Kenaf bast fiber is composed of primary (P) and secondary (S) phloem fibers. The primary phloem is single layer but the secondary phloem comprised of multiple layers which decreased the number according to the height of the stem section. The higher section, the lower the number of secondary phloem layers. Layer separation was made at the middle part of a stem dan the fiber length, the weight and the viscosity (copper ethylene diamine, CED) were measured. The average fiber length as length weighted fiber length was 2.65-3.00mm (P) and 2.52-2.60mm (S). The primary phloem fiber is obviously longer than the secondary phloem fiber. The weight ratio (P/S) was 0.073. CED viscosity was 76-79cP (P) and 121-124cP (S). The primary phloem had lower viscosity. The five sample paper sheet [A) only secondary phloem, B) no separation, C) and D) increased P/S ratio and E) only primary phloem] pulps were prepared from the lower part of a stem and subjected to paper strength tests. It was shown that with the increase of the primary phloem pulp ratio give inferior strength properties that the only secondary phloem pulp. It could mainly be explained by the lower viscosity of primary phloem. It also means that the production of higher quality kenaf bast paper in strength is not possible by using the higher stem part which has more primary phloem than the lower stem part.

Keywords:  Kenaf, bast fiber, viscosity, fiber length, paper strength and phloem.

(Japan TAPPI Journal, September 2005)

Sherif  Keshk*, Wiwin Suwinarti** and Kazuhiko Sameshima**

        Three different processing sequences for pulping kenaf (Hibiscus cannabinusL.) bast fibres were tested, and the chemical composition (cellulose, hemicellulose and lignin content) and physical properties (viscosity, degree of polymerization and crystallinity index) of the extracted pulp determined.  Three processing steps were employed: treatment with (a) ammonium oxalate, (b) sodium hydroxide, and (c) acidic chlorite.  Variations in the order, conditions and duration of their application resulted in 3 different pulping methods.  The kenaf fibre treated sequentially with acidified sodium chlorite, 0.5% ammonium oxalate and 1% sodium hydroxide (AC-AO-SH₁) generated the greatest yield and highest kappa number; whereas the sample treated sequentially with 0.5% ammonium oxalate, 15% sodium hydroxide and acidic chlorite (AO-SH₁₅-AC) developed the highest viscosity. No significant difference in hemicellulose content was observed between pulping methods. While Fourier Transform Infra Red spectra (FT-IR) and X-ray diffractometry of all extracted pulp samples revealed the same chain conformation, differences in mean hydrogen bonding, relative frequency of ether linkages and crystallinity index were apparent.  X-ray diffractograms indicated the presence  of residual oxidized lignin between the (11^¯0) planes of the fibres subjected to AC-AO-SH₁ processing sequence that were absent from fibres processed differently. Overall, the AO-SH₁₅-AC sequence is the best processing option, generating a good viscosity and crystallinity index.

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

(Industrial Crops and Products, Submitted)