Publications (4)5.48 Total impact
Article: Surface modification of bacterial cellulose nanofibers for property enhancement of optically transparent composites: dependence on acetyl-group DS.[show abstract] [hide abstract]
ABSTRACT: Bacterial cellulose (BC) nanofibers were acetylated to enhance the properties of optically transparent composites of acrylic resin reinforced with the nanofibers. A series of BC nanofibers acetylated from degree-of-substitution (DS) 0 to 1.76 were obtained. X-ray diffraction profiles indicated that acetylation proceeded from the surface to the core of BC nanofibers, and scanning electron microscopy images showed that the volume of nanofibers increases by the bulky acetyl group. Since acetylation decreased the refractive index of cellulose, regular transmittance of composites comprised of 63% BC nanofiber was improved, and deterioration at 580 nm because of fiber reinforcement was suppressed to only 3.4%. Acetylation of nanofibers changed their surface properties and reduced the moisture content of the composite to about one-third that of untreated composite, although excessive acetylation increased hygroscopicity. Furthermore, acetylation was found to reduce the coefficient of thermal expansion of a BC sheet from 3 x 10(-6) to below 1 x 10(-6) 1/K.Biomacromolecules 07/2007; 8(6):1973-8. · 5.48 Impact Factor
Article: Fiber-content dependency of the optical transparency and thermal expansion of bacterial nanofiber reinforced composites[show abstract] [hide abstract]
ABSTRACT: We produced transparent nanocomposite reinforced with bacterial cellulose having a wide range of fiber contents, from 7.4 to 66.1 wt %, by the combination of heat drying and organic solvent exchange methods. The addition of only 7.4 wt % of bacterial cellulose nanofibers, which deteriorated light transmittance by only 2.4%, was able to reduce the coefficient of thermal expansion of acrylic resin from 86×10–6 to 38×10–6 K–1. As such, the nanofiber network of bacterial cellulose has an extraordinary potential as a reinforcement to obtain optically transparent and low thermal expansion materials.
Article: Optically transparent bionanofiber composites with low sensitivity to refractive index of the polymer matrix[show abstract] [hide abstract]
ABSTRACT: Transparent polymers were reinforced by bacterial cellulose (BC) nanofibers, which are 10×50 nm ribbon-shaped fibers. They exhibited high luminous transmittance at a fiber content as high as 60 wt %, and low sensitivity to a variety of refractive indices of matrix resins. Due to the nanofiber size effect, high transparency was obtained against a wider distribution of refractive index of resins from 1.492 to 1.636 at 20 °C. The optical transparency was also surprisingly insensitive to temperature increases up to 80 °C. As such, BC nanofibers appear to be viable candidates for optically transparent reinforcement.
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ABSTRACT: The authors studied acetylation of bacterial cellulose (BC) nanofibers to widen the applications of BC nanocomposites in optoelectronic devices. The slight acetylation of BC nanofibers significantly reduces the hygroscopicity of BC nanocomposites, while maintaining their high optical transparency and thermal stability. Furthermore, the degradation in optical transparency at elevated temperature (200 °C) was significantly reduced by acetylation treatment. Therefore, the acetylation of bionanofibers has an extraordinary potential as treatment for property enhancement of bionanofiber composites.