NIPPON GOMU KYOKAISHI
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Volume 85, Issue 12
Displaying 1-9 of 9 articles from this issue
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Introductory Remarks
Special Issue for General Reviews “Cellulose nano-fiber (1) Basic structure of cellulose and preparation methods of nano-fiber”
General Reviews
  • Production of Cellulose Nanofibers and Their Applications
    Hiroyuki Yano
    2012 Volume 85 Issue 12 Pages 376-381
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.376
    JOURNAL FREE ACCESS
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    The plant pulp consists of a cellulose nanofiber or a cellulose microfibril bundle. Since nanofibers are bundles of semi-crystalline extended cellulose chains, their thermal expansion is as low as that of quartz whilst their strength is five times that of steel. Recently, due to the risk of depletion of oil reserves and global environmental concern, the extraction of cellulose nanofibers and their utilizations has gained increasing attention. This review summarizes the research works on the production of nanofibers from plant resources and their application in polymer composites.
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  • Fundamental Structure and Its Distribution in Nature
    Yoshiki HORIKAWA, Junji SUGIYAMA
    2012 Volume 85 Issue 12 Pages 382-387
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.382
    JOURNAL FREE ACCESS
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    Cellulose, a linear β-1,4-linked-homoglucan polymer, is the most abundant organic molecule in the biosphere and attracted fiber for an advanced functional materials. Cellulose-synthesizing organisms are widely distributed in biological kingdoms, ranging from Monera to Plantae and even to Animaria, tunicates. In this chapter, basic structure of cellulose microfibril and their diversity are reviewed in terms of crystalline allomorphism, cross-sectional shape, uniplanar orientation behavior and morphology of cellulose synthase complexes.
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  • Composite Materials of TEMPO-Oxidized Cellulose Single Nanofiber
    Akira ISOGAI
    2012 Volume 85 Issue 12 Pages 388-393
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.388
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    When TEMPO-mediated oxidation is applied to wood celluloses in water at pH 10 under suitable conditions, almost all glucosyl units exposed on crystalline cellulose microfibrils are selectively oxidized to sodium glucuronosyl units. The TEMPO-oxidized celluloses thus obtained have the same fibrous morphologies as those of the original wood celluloses. Mild mechanical disintegration of the fibrous TEMPO-oxidized celluloses in water in turn allows them to be converted to highly viscous and transparent gels consisting of individually fibrillated TEMPO-oxidized cellulose single nanofibers (TOCNs) uniform 3-4 nm in width and over 1 μm in length. Because anionically charged sodium carboxylate groups are present on the crystalline TEMPO-oxidized cellulose microfibril surfaces in high densities, electrostatic repulsion and osmotic effect efficiently work between the microfibrils, resulting in the complete nanofibrillation of wood cellulose microfibrils. The TOCNs and their counter ion-exchanged TOCNs can be converted to self-standing films, hydrogels, aerogels, multi-layered composite films, polymer-nanocomposites, nanoclay-composites and others, which show high mechanical properties, high optical transparencies, high gas-barrier properties, low thermal expansion coefficients, high thermal stabilities, high catalytic behavior, spider web-like nano-networks, and other unique properties, when prepared under adequate conditions. Thus, TOCNs are expected to be used as new bio-based nanofibers for versatile applications in high-tech fields.
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  • Cellulose nano sizing by enzymatic treatment
    Noriko HAYASHI
    2012 Volume 85 Issue 12 Pages 394-399
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.394
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    In recent years, enormous researches on cellulose nanofiber have been reported. For the preparation of these cellulose nanofiber, acid hydrolysis or mechanical crushing is commonly used. Cellulase attacks cellulose, and sometimes it splits cellulose. This process is to be available for the production of cellulose nanofiber, and this will reduce the environmental impact during the process. For instance, endoglucanase treatment was processed to the high crystalline cellulose microfibril while adding mechanical processing such as ball milling, the cellulose microfibril split and the diameter of the fiber became thinner than the original one.
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  • Preparation of Single Cellulose Nanofibers Dispersed in Water Using Aqueous Counter Collision Method
    Tetsuo Kondo
    2012 Volume 85 Issue 12 Pages 400-405
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.400
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    Recently, the authors proposed aqueous counter collision (= ACC) method to allow bio-based materials to be downsized into nano-objects only using a pair of high speeded water jets as the medium without chemical modification of molecules including depolymerization. In this ACC system, an aqueous suspension containing micro-seized samples, which are pre-divided into a pair of facing nozzles, are supposed to collide with each other at a high rate, resulting in wet and rapid pulverization of the samples into nano-scaled objects dispersed in water. The obtained materials are more downsized by repeating the collision and increasing in the ejecting pressure. In particular, width of the ACC-treated objects was controlled as desired on the nanoscales, resulting in preferable larger specific surface areas. The fibers thus prepared are expected to exhibit unique morphological properties including change of the crystalline form. In this review, the author will describe a general introduction of ACC method, and then an example of the ACC method for microbial cellulose pellicle produced by Gluconacetobacter xylinus to provide the characteristic single cellulose nanofibers having a high adsorptivity including alteration of crystalline phases. The properties can open up further pathways into versatile applications such as unique composite materials and coating agents.
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  • Synthesis of Cellulose by Bacteria
    Kenji TAJIMA
    2012 Volume 85 Issue 12 Pages 406-411
    Published: 2012
    Released on J-STAGE: August 02, 2013
    DOIhttps://doi.org/10.2324/gomu.85.406
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    Cellulose is the most abundant biopolymer in nature and is utilized in a wide variety of industries. Although plants produce the most cellulose, some animals and bacteria also produce cellulose. Acetobacter (=Gluconacetobacter), which is a Gram-negative bacterium, produces cellulose called bacterial cellulose (BC) from glucose on the surface of a culture medium. Even in plants, there is little knowledge concerning the mechanisms of cellulose biosynthesis. Due to its ease of handling, Acetobacter xylinum (A. xylinum) has been studied as a model organism of cellulose production. BC has exceptional physicochemical properties, such as ultrafine reticulated structure, high crystallinity, high tensile strength, high hydrophilicity, moldability during formation, and biocompatibility, although its chemical structure is the same as those of the cellulose produced by plants and algae. These remarkable characteristics are of interest for the development and manufacture of a wide range of materials, such as food matrices, dietary fiber, acoustic membranes, special biomaterials. In this article, I introduce cellulose synthesis by bacteria (features and applications) and the synthetic mechanism of BC.
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Technical Note
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