Faculty Profiles - YAMAMOTO Tetsuya

Effect of the surface properties of particle on the classification performance of a dry-cyclone Reviewed

Development of Techniques for Dispersion of Hydrophobic Powder in Water Using Particles

Vol. 25 page： 113-118 2018.5

Tetsuya Yamamoto, Motoharu Higashino

Particulate Science and Technology Vol. 36 ( 1 ) page： 46 - 49 2018.1

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Taylor and Francis Inc.

The purpose of the present study was to investigate the effect of the surface properties of silica particles on the classification performance of a dry-cyclone. As a result, it was clear that the separation force between the surface of particle and the silicon was decreased by the AFM measurement when the surface of the silica particles could be modified with ethanol or acetone treatment. Fine particles in the original silica particles with the treatments were easily collected by the filter in a dry-cyclone system
hence, the particle classification performance was enhanced.

DOI： 10.1080/02726351.2016.1205691

Enhancement of surface adhesion between thermoplastic resin and carbon fiber using polymer colloids Reviewed

Enhancement of mechanical properties of carbon fiber reinforced thermoplastic using colloidal techniques Reviewed

Tetsuya Yamamoto, Katsumasa Uematsu, Syo Yabushita

Procedia Manufacturing Vol. 15 page： 1738 - 1745 2018

炭素繊維強化熱可塑性樹脂の高性能化を実現する界面制御技術の開発

山本徹也

新東技報 Vol. 35 page： 70-72 2017.12

Tetsuya Yamamoto, Katsumasa Uematsu, Toshihira Irisawa, Yasuhiro Tanabe

The Journal of Adhesion Vol. 93 ( 12 ) page： 943 - 948 2017.10

Improved mechanical properties of PMMA composites: Dispersion, diffusion and surface adhesion of recycled carbon fiber fillers from CFRP with adsorbed particulate PMMA Reviewed

Tetsuya Yamamoto, Yuta Makino, Katsumasa Uematsu

Advanced Powder Technology Vol. 28 ( 10 ) page： 2774 - 2778 2017.10

In-situ Adsorption of Polymer Particles on Multi-wall Carbon Nanotubes Using Colloidal Techniques Reviewed

Tetsuya Yamamoto, Naoya Toyoda

Colloids and Interface Science Communications Vol. 20 page： 1 - 4 2017.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.

A novel technique for the adsorption of polymer particles on carbon nanotubes was developed. First, the surfaces of multi-wall carbon nanotubes (MWCNTs) were coated with poly(N-vinyl acetamide) (PNVA) to confer them hydrophilicity together with good dispersion stability in water owing to a steric effect between the hydration layers. Second, the hydrophilic MWCNTs were covered with polymethyl methacrylate (PMMA) particles bearing positive charges—synthesized using V-50—through electrostatic interactions. These polymers were obtained by soap-free emulsion polymerization. The in-situ adsorption of PMMA particles on surface MWCNTs were attributed to the hydration layers of the modified MWCNTs, and electrostatic interactions between PMMA particles and the modified MWCNTs. It can be expected that the PMMA particles adsorbed on the carbon nanotubes hold the potential to serve as glue between carbon nanotube and PMMA in the composite.

DOI： 10.1016/j.colcom.2017.07.003

Synthesis and Electrical Properties of Composite Films Comprising Polymer Particles and Carbon Nanotubes Reviewed

Tetsuya Yamamoto, Kan Kawaguchi

Colloids and Interface Science Communications Vol. 20 page： 5 - 8 2017.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.

In the present study, composite films were synthesized from composite polymer particles prepared with multi-wall carbon nanotubes (MWCNTs) by in situ polymerization. Because one of the advantages of MWCNTs compared to other preparation methods is high electrical conductivity, the electrical properties of the composite films were evaluated by the direct current two-terminal method. As a result, the composite film prepared by MWCNTs had conductive paths and showed higher conductivity even at lower mass fraction of MWCNTs compared with the previous works to keep transparency. This method was shown to decrease the mass fractions of MWCNTs and increase the transparency of the composite films.

DOI： 10.1016/j.colcom.2017.08.001

Synthesis of composite polymer particles with carbon nanotubes and evaluation of their mechanical properties Reviewed

Tetsuya Yamamoto, Kan Kawaguchi

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS Vol. 529 page： 765 - 770 2017.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

In the present study, a method for synthesizing composite polymer particles with multi-wall carbon nanotubes (MWCNTs) was developed, and the particles' mechanical properties were evaluated. First, the surfaces of MWCNTs were modified by acids to increase their hydrophilicity, resulting in surface-active MWCNTs. Then, a Pickering emulsion was formed using liquid benzyl methacrylate monomer and the surface-active MWCNTs. The surface charge of the surface-active MWCNTs greatly influenced the surface coverage and size of the composite particles. Furthermore, when untreated MWCNTs were added to the monomer phase, surface coverage of the resulting particles was enhanced because MWCNTs on the surface of the particles interacted with MWCNTs incorporated inside the particles, thus preventing the surface-active MWCNTs on the surface from being released into the bulk. As a result, the mechanical properties of the composite polymer particles were successfully improved because the incorporated MWCNTs worked well as fillers.

DOI： 10.1016/j.colsurfa.2017.05.075

Anomalous particle through soap-free emulsion polymerization of styrene using oil-soluble initiator Reviewed

Tetsuya Yamamoto, SeulChan Kim

JOURNAL OF POLYMER RESEARCH Vol. 24 ( 9 ) page： 149 2017.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

One of oil-soluble initiators, VF-096, might work as cross-linker. This initiator would enable to synthesize the particle with cross-linking, which was involved with the particle morphology. Soap-free emulsion polymerization of styrene using this initiator was carried out to develop the method to control the particle morphology in one batch system. As a result, it was found that anomalous particle was generated without stirring and the particle morphology changed to be spherical by increasing shear stress through the stirring. One of the origins of the anomalous particle was the phase separation of the water in the particle and release of it from inside of the particle to the bulk.

DOI： 10.1007/s10965-017-1316-2

Controlling the particle cut size of a dry cyclone using acetone Reviewed

Tetsuya Yamamoto, Motoharu Higashino

Particulate Science and Technology Vol. 35 ( 2 ) page： 214 - 218 2017.3

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Taylor and Francis Inc.

In this study, we investigated the interaction between particles and the wall in the presence of mist to improve the particle classification performance of a dry cyclone. The interaction between a silica particle and a mica surface in the presence of a flowing acetone mist was measured by performing atomic force microscopy (AFM), which showed that an attractive force was generated and became stronger as time passed while acetone mist was supplied to the system, probably because of static electricity. In a dry cyclone system, this attractive force could enhance the classification performance. In particular, when acetone mist was supplied into the cyclone from the upper part of the dust box at higher flow rates, the classification performance was enhanced. Because acetone is highly volatile and has a low viscosity, the classification performance was improved by the evaporated acetone even when a cyclone with a dust box filled with acetone was used instead of a nozzle supplying the mist. In this case, the ratio of the mass of the particles collected by the upper part of the cyclone to the total mass of the feed powder was increased, probably because of the attractive force between the silica particles and the wall of the cyclone. Moreover, the cut size of the dry cyclone could be controlled by changing the amount of acetone in the dust box of the cyclone.

DOI： 10.1080/02726351.2016.1150370

Synthesis of hydrocolloid through polymerization of styrene and N-vinyl acetamide by AIBN Reviewed

CFRTPの高性能化を実現するコロイド技術 Invited

山本徹也

化学装置 Vol. 59 ( 3 ) page： 45 - 48 2017.3

Tetsuya Yamamoto, Yuya Takahashi

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS Vol. 516 page： 80 - 84 2017.3

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The soap-free emulsion polymerization of styrene with hydrophilic monomer, N-vinyl acetamide (NVA), using oil-soluble initiator was carried out to synthesize polymeric particles with good dispersion stability and improve the polymer yield. As a result, it was found that the polymer yield and dispersion stability were enhanced by the promotion of polymerization by the dissolved monomers and hydrogen bonding between NVA on the particle surface and water molecules in the bulk. Accordingly, this polymer colloid showed the nature of hydrocolloid by their hydration layers because its dispersion stability was kept even when the electrolytes were added to the system. In the conventional soap-free emulsion polymerization, the counter ions including the water-soluble initiators were remained in the water phase. However, because all of chemical components in the present study were consumed for the polymerization, the impurities except polymers were hardly remained in the bulk. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2016.12.023

Controlling of the interfacial shear strength between thermoplastic resin and carbon fiber by adsorbing polymer particles on carbon fiber using electrophoresis Reviewed

炭素繊維強化熱可塑性樹脂の高性能化を実現するコロイド技術 Invited Reviewed

山本徹也、上松克匡、入澤寿平、田邊靖博

粉体工学会誌 Vol. 53 ( 12 ) page： 786 - 791 2016.12

Tetsuya Yamamoto, Katsumasa Uematsu, Toshihira Irisawa, Yasuhiro Tanabe

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING Vol. 88 page： 75 - 78 2016.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

In order to control the interfacial adhesion between carbon fibers and thermoplastic resins, poly(methyl methacrylate) (PMMA) particles have been adsorbed on the carbon fiber surfaces using an electrophoresis process. The amount of PMMA particles adsorbed on the modified carbon fibers was varied using the electrophoresis technique performed in polymer colloids for a short time. Additionally, the interfacial shear strength between the modified carbon fiber and the resin was controlled by a modification of the present process. An improved interaction and a strengthened surface adhesion between the carbon fiber coated with particles and the PMMA resin were observed. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.compositesa.2016.05.021

Particle size control in the soap-free emulsion polymerization of styrene by an oil-soluble initiator with a weakly acidic water-soluble initiator Reviewed

Tetsuya Yamamoto, Kan Kawaguchi, Yuya Takahashi

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS Vol. 502 page： 1 - 5 2016.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The soap-free emulsion polymerization of styrene by an oil-soluble initiator, 2,2'-azobis(2-methylpropionitrile) (AIBN), with a water-soluble initiator, 4,4'-azobis(4-cyanovaleric acid) (V-501), was conducted in water to control the size of the synthesized polymeric particles. The particle size and surface potential were monitored as concentration of V-501 used for the polymerization was varied. When the V-501 concentration was increased, the particle size increased because V-501 was a weak acid and reduced the surface potential, thereby promoting particle growth through coagulation. Additionally, V-501 can also function as a radical initiator, increasing the efficiency of the polymerization reaction and, thus, the number concentration of the particles. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2016.04.048

Effect of the Amount of pi Electrons in Aromatic Monomer on the Surface Potential of Polymeric Particles Obtained through Soap-free Emulsion Polymerization Using AIBN Reviewed

Relationship between Surface Potential and Particle Size in Soap-free Emulsion Copolymerization of Styrene and Methyl Methacrylate using a Water- or Oil-soluble Initiator Reviewed

Colloid & Polymer Science Vol. 294 page： 281 - 284 2016.2

Tetsuya Yamamoto

CHEMISTRY LETTERS Vol. 44 ( 11 ) page： 1555 - 1556 2015.11

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

The surface potential of polymeric particles obtained through soap-free emulsion polymerization using an oil-soluble initiator, 2,2'-azobis(2-methylpropionitrile) (AIBN), depended on the monomer used in the polymerization. Changing the amount of it electrons in the aromatic monomer enabled control of the surface potential of the synthesized particles. It was found that the negative charges of the synthesized particles were strengthened for their sizes to be reduced gradually as the amount of it electrons in the monomer was increased.

DOI： 10.1246/cl.150759

Effect of Counter Ionic Radius in Initiator on Particle Size in Soap-free Emulsion Polymerization of Styrene Reviewed

Tetsuya Yamamoto, Taichi Yokoyama

CHEMISTRY LETTERS Vol. 44 ( 6 ) page： 824 - 825 2015.6

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

Soap-free emulsion polymerization of styrene was carried out to synthesize particles with the size under 100 nm. Changing the concentration of initiator, VA-044, enabled us to control the size under 100 nm in soap-free emulsion polymerization of styrene. Furthermore, making the counter ion radius in initiator smaller was effective for reducing the size of particles in the polymerization.

DOI： 10.1246/cl.150148