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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)

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)