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Suzuki S.,Kyoto University | Suzuki S.,Kochi Prefectural Paper Technology Center | Suzuki F.,Kyoto University | Kanie Y.,Kyoto University | And 4 more authors.
Cellulose | Year: 2012

The structure and crystallization of carefully isolated sub-elementary fibrils (SEFs) of bacterial cellulose have been investigated using TEM, WAXD, and high-resolution solid-state 13C NMR. The addition of a suitable amount of fluorescent brightener (FB) to the incubation medium of Acetobacter xylinum effectively suppressed the aggregation of the SEFs into the microfibrils, as previously reported. However, this study confirmed for the first time that serious structural change in the SEFs occurs during the removal of excess FB by washing with buffer solutions having pH values higher than 6 or with the alkaline aqueous solution that was frequently used in previous studies. In contrast, the isolation of unmodified SEFs was successfully performed by utilizing a washing protocol employing pH 7 citrate-phosphate buffer solution containing 1% sodium dodecyl sulfate. High-resolution solid-state 13C NMR and WAXD measurements revealed that the SEFs thus isolated are in the noncrystalline state in which the pyranose rings of the almost parallel cellulose chains appear to be stacked on each other. The respective CH 2OH groups of the SEFs adopt the gt conformation instead of the tg conformation found in cellulose I α and I β crystals, and undergo significantly enhanced molecular motion in the absence of intermolecular hydrogen bonding associated with these groups. The main chains are also subject to rapid motional fluctuations while maintaining the parallel orientation of the respective chains, indicating that the SEFs have a liquid crystal-like structure with high molecular mobility. Moreover, the SEFs crystallize into cellulose I β when the FB molecules that may adhere to the surface of the SEFs are removed by extraction with boiling 70 v/v% ethanol and 0.1N NaOH aqueous solution. On the basis of these results, the crystallization of the SEFs into the I α and I β forms is discussed, including the possible formation of the crystalline-noncrystalline periodic structure in native cellulose. © 2012 Springer Science+Business Media B.V.


Win K.R.,Tokyo University of Agriculture and Technology | Ariyoshi M.,Tokyo University of Agriculture and Technology | Seki M.,Kochi Prefectural Paper Technology Center | Okayama T.,Tokyo University of Agriculture and Technology
Sen'i Gakkaishi | Year: 2012

We investigated the effect of pulping processes on the strength properties of bamboo paper. Bamboo was pulped by hand and by the kraft process. Handsheets were formed from the pulps obtained and their properties were measured before and after accelerated aging. The pulp made by hand had lower water retention and higher initial viscosity than the kraft pulp. Paper made from the hand-made pulp had considerably higher aging resistance than paper made from the kraft pulp. All the measurements revealed that acid-free paper made from the hand-made pulp retained its mechanical strength (especially folding endurance) better during accelerated aging than acid-free paper made from the kraft pulp. Retention of the folding endurance depended considerably on the retention of the zero-span tensile strength during sealed-tube aging. With the exception of zero-span tensile strength, hand-pulped and kraft-pulped acidic papers did not exhibit any significant difference in their mechanical properties. Although the paper made from the hand -made pulp had higher sheet strength than the paper made from the kraft pulp, both papers exhibited similar reductions in the surface pH during tube aging. Before and after accelerated aging, the paper made from kraft pulp produced by cooking at 170 °C for 90 min had higher intrinsic fiber strength than the paper made from kraft pulp produced by cooking at 160 °C for 60 min for both acid-free and acidic papers.


Sumida T.,Kochi Prefectural Industrial Technology Center | Yano Y.,Kochi Prefectural Industrial Technology Center | Okazaki Y.,Kochi Prefectural Industrial Technology Center | Yamashita M.,Kochi Prefectural Paper Technology Center | And 2 more authors.
Bunseki Kagaku | Year: 2015

Novel cellulose functionalized with polyallylamine based on wood powder was synthesized. It was applied to the collection of gold in gold-plating waste. The synthesized adsorbent, cellulose-pentaerythritol polyglycidyl ether-polyallylamine-glutaraldehyde-polyvinyl alcohol (CPP-GP), showed good adsorption behavior toward gold and palladium compared to other anions. The pH range for the adsorption of gold was about 4̶6, and this maximum adsorption capacity was 8.4 % in gold-plating waste. By X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS) of CPP-GP adsorbent, which adsorbed gold in plating waste, the adsorbent was found to be combined in form of gold(I) cyanide. A column method with CPP-GP adsorbent was successfully applied to the collection of gold in 90 L of gold-plating waste with satisfactory results, which this recovery of gold could obtain about 87 %. © 2014 The Japan Society for Analytical Chemistry.


Suzuki S.,Kyoto University | Suzuki S.,Kochi Prefectural Paper Technology Center | Hirai A.,Kyoto University | Horii F.,Kyoto University
Cellulose | Year: 2012

The formation and structure of the complexes of sub-elementary fibrils (SEFs) of bacterial cellulose with fluorescent brightener (FB) molecules have been investigated using WAXD, SEM, and computer calculations of WAXD profiles. It is confirmed for the first time that the SEF-FB complexes are formed in 10 min by washing the cultivation product, which is prepared by the culture of Acetobacter xylinum in the presence of FB, with the pH 7 citrate-phosphate buffer solution and their thin sheet-like structure is grown almost two-dimensionally in 24 h in the medium. The same SEF-FB complexes are also produced by washing the product with NaCl aqueous solutions having concentrations higher than 0.1 wt%, while the original SEF structure is unchanged at lower concentrations. This indicates that the concentration of salt ions in washing media is a main factor to dominate the formation of the SEF-FB complexes from the cultivation product. The calculations of WAXD profiles reveal that the chain-slid, parallel-set, and sheet-slid/contracted models well reproduce the WAXD profile observed for the SEF-FB complexes. In these models, the following modifications are conducted in the a,b-modified unit cell of cellulose I β; the slide of the center chain along the b″ axis, the rotation of each chain around its own molecular axis, and the slide and contraction of the individual sheets composed of the center or origin chains. A single FB molecule is successfully packed into an energetically-allowable space in between the (010) planes in the 2a″ × b″ × 4c″ cell for the chain-slid model or in between the corresponding planes for the parallel-set and sheet-slid/contracted models. However, the detailed structure of FB in the complex is not yet determined due to the low crystallinity of the complexes. © 2012 Springer Science+Business Media B.V.


Win K.K.,Tokyo University of Agriculture and Technology | Ariyoshi M.,Kochi Prefectural Paper Technology Center | Seki M.,Kochi Prefectural Paper Technology Center | Okayama T.,Tokyo University of Agriculture and Technology
16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC | Year: 2011

To evaluate the degradation of paper made from bamboo pulp, accelerated aging tests (dry heat treatment at 105 °C, moist heat treatment at 80 °C and 65% RH, and heat treatment in a sealed tube at 100 °C) were performed. The results were used to predict the long-term effects of natural aging. Acid-free laboratory sheet prepared from bamboo pulp exhibited higher tearing strength and zero-span tensile strength, compared with sheets made from hardwood pulps. However bamboo sheet tended to degrade rapidly in accelerated aging tests. This might be related to the rapid reduction in the viscosity number of bamboo pulps during accelerated aging tests. Two mass deacidification techniques have been employed in Japan to suppress degradation of acidic paper: the Bookkeeper (liquid phase) and dry ammonia-ethylene oxide (gaseous phase) (DAE) processes. Both these mass deacidification processes increased surface pH of acidic bamboo and hardwood papers. These processes also suppressed reduction in surface pH and loss in paper strengths such as tearing strength, the zero-span tensile strength and folding endurance during the accelerated aging test in the sealed tube. The Bookkeeper process gave higher strengths than the DAE process after extended accelerated aging of bamboo paper.

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