Hamamatsu, Japan
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Kojima Y.,University of Shizuoka | Ishino A.,University of Shizuoka | Kobori H.,University of Shizuoka | Suzuki S.,University of Shizuoka | And 4 more authors.
Journal of Wood Science | Year: 2015

Wood-based materials are widely used in residential construction. These materials can be made from virgin or recycled wood, and most of the materials are fabricated with chemical adhesives. Finding replacements for such chemical adhesives poses major challenges. This study explored nanofiber technology as an alternative to these adhesives. Previous studies have shown that the three-dimensional binding effects of cellulose nanofiber (CNF) and ligno-cellulose nanofiber (LCNF), when mixed with wood flour, can significantly improve the physical and mechanical properties of wood flour board. We use the word “LCNF” as the surface nanofibrillated wood flour. Previous studies have also highlighted problems that occur during compounding and board manufacturing. In this study, a reliable method was established to mix wood flour and LCNF. The method involved a compounding machine, which facilitated board manufacturing safely. Physical and mechanical properties of the resulting wood flour boards were significantly improved with the addition of LCNF, due to close binding between LCNF and wood flour particles. © 2015 The Japan Wood Research Society


Isa A.,Ehime University | Minamino J.,University of Shizuoka | Kojima Y.,University of Shizuoka | Suzuki S.,University of Shizuoka | And 4 more authors.
Journal of Wood Chemistry and Technology | Year: 2016

In this study, we evaluated the influence of wood flour (particle size: <90 m) on the physical properties of wood flour/polypropylene (PP) composites. Wood flour was obtained by dry ball-milling of forest-thinning material at a rotary speed of 250 rpm for 1, 2, 4, and 8 h. The milled wood flour was filtered using a 90 m sieve. The water content of the wood flour was adjusted to 5, 10, or 20 wt%. Composite properties, including mechanical properties, water absorption, and thermal expansion, were evaluated at wood flour loadings of 40 wt%. When wood flour with 5 wt% water content was milled for 2 and 4 h, the resulting wood flour was granular rather than fibrous; flocculation of the fine particles was observed for milling times exceeding 4 h. This morphological change in the wood flour reduced its influence on the physical properties of the composites, although some positive influences were observed on the molding properties of the composite, such as an increase in compound fluidity. Milled wood flour with 10 wt% or 20 wt% water content was fibrous. Scanning electron microscopy observation of milled wood flour with 10 wt% water content revealed partial surface fibrillation at widths of tens to hundreds of nanometers. The addition of wood flour with nanoscale surface fibrils to PP composites positively influenced the properties of the composite, resulting in a decrease in the linear coefficient of thermal expansion in the flow direction. © Taylor & Francis Group, LLC.


Kojima Y.,University of Shizuoka | Isa A.,University of Shizuoka | Kobori H.,University of Shizuoka | Suzuki S.,University of Shizuoka | And 3 more authors.
Materials | Year: 2014

Wood-based materials are used extensively in residual construction worldwide. Most of the adhesives used in wood-based materials are derived from fossil resources, and some are not environmentally friendly. This study explores nanofiber technology as an alternative to such adhesives. Previous studies have shown that the three-dimensional binding effects of cellulose nanofiber (CNF), when mixed with wood flour, can significantly improve the physical and mechanical properties of wood flour board. In this study, ligno-cellulose nanofibers (LCNF) were fabricated by wet disk milling of wood flour. Composite boards of wood flour and LCNF were produced to investigate the binding effect(s) of LCNF. The fabrication of LCNF by disk milling was simple and effective, and its incorporation into wood flour board significantly enhanced the physical and mechanical properties of the board. © 2014 by the authors.


Kojima Y.,University of Shizuoka | Kawabata A.,University of Shizuoka | Kobori H.,University of Shizuoka | Suzuki S.,University of Shizuoka | And 3 more authors.
Journal of Wood Science | Year: 2016

Wood-based materials are fabricated with adhesives composed of various materials derived from fossil fuels. It is difficult to identify replacements for these chemical adhesives. This study explored nanofiber technologies as an alternative to these adhesives. In this study, we focused on reinforcement effects of lingo-cellulose nanofiber (LCNF) on fiberboards made from softwood and hardwood fiber. We discuss the density effects of reinforcement with LCNF because the density of medium-density fiberboard (MDF), which is widely used for construction, is standardized at about 0.60–0.80 g/cm3. Fiberboards were manufactured with three densities (0.60, 0.75, and 1.00 g/cm3). For softwood fiberboards, the bending properties for LCNF-mixed boards were higher than those for the control fiberboards at all densities. In this paper, control fiberboard means fiberboard with fiber only. For hardwood fiberboards, the bending properties for LCNF-mixed fiberboard for 1.00 g/cm3-density board were higher than those for the control fiberboard. For internal bond strength (IB), the IB for LCNF-mixed fiberboard was higher than that for the control fiberboard. The thickness swelling (TS) and weight change (WC) with water absorption for fiberboards containing LCNF were lower than those for control fiberboards. As a conclusion, physical and mechanical properties of the resulting fiberboards were significantly improved with the addition of LCNF, especially for softwood fiberboards, due to close binding between LCNF and wood fibers. © 2016 The Japan Wood Research Society


Iwamoto S.,Japan National Institute of Advanced Industrial Science and Technology | Yamamoto S.,Japan National Institute of Advanced Industrial Science and Technology | Lee S.-H.,Kangwon National University | Ito H.,TOCLAS Corporation | Endo T.,Japan National Institute of Advanced Industrial Science and Technology
Materials | Year: 2014

Lignocellulose nanofibers were prepared by the wet disk milling of wood flour. First, an ethylene-butene copolymer was pre-compounded with wood flour or lignocellulose nanofibers to prepare master batches. This process involved evaporating the water of the lignocellulose nanofiber suspension during compounding with ethylene-butene copolymer by heating at 105 °C. These master batches were compounded again with polypropylene to obtain the final composites. Since ethylene-butene copolymer is an elastomer, its addition increased the impact strength of polypropylene but decreased the stiffness. In contrast, the wood flour- and lignocellulose nanofiber-reinforced composites showed significantly higher flexural moduli and slightly higher flexural yield stresses than did the ethylene-butene/polypropylene blends. Further, the wood flour composites exhibited brittle fractures during tensile tests and had lower impact strengths than those of the ethylene-butene/polypropylene blends. On the other hand, the addition of the lignocellulose nanofibers did not decrease the impact strength of the ethylene-butene/polypropylene blends. Finally, the addition of wood flour and the lignocellulose nanofibers increased the crystallization temperature and crystallization rate of polypropylene. The increases were more remarkable in the case of the lignocellulose nanofibers than for wood flour. © 2014 by the authors.


Nordin M.N.A.,Yamaguchi University | Nordin M.N.A.,University Technical Malaysia Melaka | Makino Y.,Yamaguchi University | Goda K.,Yamaguchi University | Ito H.,TOCLAS Corporation
Sen'i Gakkaishi | Year: 2015

Fatigue fracture properties of wood plastic composites (WPC) were investigated. The material was based on a wood flour/polypropylene (PP) master batch, and prepared to be 30wt% and 50wt% wood flour contents by the addition of PP pellets. First, kneading temperature and screw speed of a uni-axial extruder were changed in some conditions, and 190°C and 20rpm were decided from tensile test of the injection-molded WPC specimens as the optimum manufacturing conditions. Next, tensile and fatigue tests were carried out for WPC specimens with 30wt% and 50wt% wood flour contents. The resultant tensile strength and fatigue life were largely improved as compared to neat PP specimens. When a lump of the master batch remained in the WPC specimen, the strength and life were reduced. It should be noted that, while fatigue life of the neat PP specimens was only 10 to 102 cycles to failure range at 30MPa maximum cyclic stress, those of WPC specimens with 30wt% and 50wt% contents were drastically extended to 103 to 104, and 105 to 106 cycles to failure, respectively. It was estimated that the major cause of fatigue damage in WPC specimens was craze occurring in the matrix, which initiated near the specimen surface, extended into the inner, and finally led to the unstable fracture.


Suzuki T.-A.,Industrial Research Institute of Shizuoka Prefecture | Sukoyaka S.,TOCLAS CORPORATION
Journal of Light and Visual Environment | Year: 2014

This study aimed at estimating the brightness of a monochromatic LED point source as perceived by the elderly and protanopes. In order to estimate the perceived brightness of the monochromatic LED point source for the elderly and protanopes, we defined an index, brightness perception efficiency, which is a ratio of perceived luminosity with spectral luminous efficiency of the elderly or protanopes to the luminosity with standard spectral luminous efficiency. The brightness perception efficiency was calculated using both the LED spectral radiant intensity defined by a peak wavelength and a full width at half maximum (FWHM) of the LED, and the spectral luminous efficiencies of the elderly in their 70s and protanopes. The brightness perception efficiency indicated that monochromatic LED point sources with a broad FWHM effectively attenuate the reduction in perceived brightness of the elderly and protanopes. It is expected that in the case of a peak wavelength of 475 nm the elderly perceive brightness equivalent to 1.6 times luminosity for the LED with a FWHM of 100 nm compared to that with a FWHM of 15 nm, and in the case of a peak wavelength of 63537 nm protanopes perceived brightness equivalent to about 3 times luminosity for the LED with a FWHM of 100 nm compared to that with a FWHM of 15 nm. Based on the brightness perception efficiency, we developed an LED illumination simulator that allows the young observers with normal color vision to experience the brightness perceived by the elderly and protanopes. © 2014, The Illuminating Engineering Institute of Japan. All rights reserved.


Hayashi F.,Shinshu University | Shirasaki A.,Shinshu University | Wagata H.,Shinshu University | Kamikawa H.,TOCLAS Corporation | And 3 more authors.
Crystal Growth and Design | Year: 2015

Layered double hydroxide (LDH) is an environmentally benign anion exchanger that can adsorb various toxic anions. In this work, we demonstrate the fabrication of plate-like Mg-Al-type LDH crystals on in situ formed alumina particles using a flux method at a relatively low temperature (∼350 °C). At or below 300°C, the melted Al source crystallized to form AlOOH or γ-alumina particles in KNO3-NaNO3 flux. However, LDH crystals did not form due to the inferior crystallization properties of the Mg precursor. Increasing the holding temperature up to 350°C and above facilitated crystallization of the dissolved Mg and Al species in flux to yield plate-like LDH crystals on the preformed alumina particles. Top-surface and cross-sectional FE-SEM and EPMA analyses revealed the vertical alignment of the crystalline LDH plates on the surface of the alumina particles. On the other hand, solid-state reactions did not yield these well-grown, plate-like LDH crystals. The TG-DTA profile of the LDH precursors with flux depicted the decomposition and crystallization events that the Al and Mg precursors undergo. On the basis of the results from these characterization studies, we propose a mechanism in which LDH crystals sequentially form on the surface of the alumina particles. © 2014 American Chemical Society.


Nishida M.,Nagoya Institute of Technology | Furuya S.,Nagoya Institute of Technology | Ito H.,Toclas Corporation | Makise R.,Toclas Corporation | Okamoto M.,Toclas Corporation
Key Engineering Materials | Year: 2016

Wood-plastic composites (WPCs) which consist of wood flour and plastics have been widely used as architectural materials for a long time. However, the impact resistance is not always high and basic mechanical properties at high strain rate are not fully understood. In order to clarify the tensile behavior at high strain rates, split Hokinson pressure bar method was used for WPCs consisting of polypropylene. The effects of mixing ratio on the maximum stress and elongation at break were examined at high strain rates. © 2016 Trans Tech Publications, Switzerland.

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