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Volume 50, Issue 6
Special Issue of 48th Particle Technology Meeting "Surface Modification of Particulate Materials"
Displaying 1-8 of 8 articles from this issue
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Original Paper
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Toshiyuki Fujimoto, Junichi Yamauchi, Shinya Yamanaka, Yoshikazu Kuga2013 Volume 50 Issue 6 Pages 398-404
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSCopper oxide coating onto electric conductive iron particles was carried out. We have proposed a macroscopic method to examine the coating state by measuring the specific resistance of a pallet made out of coated particles. We have also performed a mass balance analysis of feed and coated particles, and X-ray diffraction analysis. Since iron and copper oxide were distinguishable by secondary electron images and backscattered electron composition images, we have investigated the microscopic cross section of the pellets and evaluated the insulation state qualitatively. Macroscopic evaluation of the coating state obtained by measurement of the specific resistance was also validated by another investigation.View full abstractDownload PDF (1101K) -
Michitaka Suzuki, Mao Yoshikawa, Kenji Iimura, Hiroshi Satone, Katsuno ...2013 Volume 50 Issue 6 Pages 405-409
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSThe glass substrate is coated by the silica nanoparticle suspension using dipping or spin coat method and dried in an electric oven. The glass substrate surface is covered with nanoparticle thin layer and the transparent and tiny rugged surface can be produced on a substrate. It was experimentally confirmed to prevent dust adhesion by covering the surface of the glass substrate with nanoparticle. But the reason why the prevention of particle adhesion on nanoparticle coating substrate is not clear yet. Therefore the adhesion force between particle and substrate is measured by the centrifugal method and the relation between the adhesion force and the surface roughness is discussed from experimental and theoretical point of view. The measured and calculated results by Van der Waals force show that adhesion force decreased with the increment of the surface roughness. From the results, nanoparticle coating is very effective to prevent the dust adhesion on the substrate and the various application of nanoparticle coating can be expected.View full abstractDownload PDF (637K) -
Naochika Asai, Hideya Nakamura, Satoru Watano2013 Volume 50 Issue 6 Pages 410-415
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSImprovement of flowability and dissolution property of particles was conducted by a dry surface modification using a novel shear mixer with a super high speed chopper (SPM mixer). Corn starch and ibuprofen were treated with silica under various rotation speeds and operation time. The flowability was evaluated by an angle of repose and dissolution property was evaluated by a dissolution test according to the Japanese Pharmacopoeia.
It was found that composite particles with good flowability were obtained within 1 minute treatment time. And it was implied that the faster rotation speed of chopper resulted in the shorter treatment time.
In the SPM mixer, surface modification and grinding were progressed simultaneously. Within 1 minute treat time, the particle size was smaller and dissolution velocity was faster by an increase of rotation speed of chopper. And composite particles with superior flowability obtained.View full abstractDownload PDF (872K) -
Shuji Hasegawa, Akio Nasu, Satoru Watano2013 Volume 50 Issue 6 Pages 416-420
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSDilatant behavior of slurries formed by cosmetic powders was analyzed by the rhelogical analysis. The slurry formed by sericite shows dilatant flow at large strain range. In case of sericite slurry, the storage modulus was larger than the loss modulus even when the strain of one hundred percent was added. Flowability depending on the thickness of synthetic micas tended to show dilatant behavior.
The reason why the cosmetic slurries showed dilatant behavior was considered that the affinity between these powders in a solution was weaker than the one between ordinal mica powders. The weak affinity of sericite and synthetic micas brought viscoelastic characters. Consequently, it was considered that they could not be easily molded. To get rid of the difficulty in molding, surface treatment of powder were found to be effective. When the surface of sericite was thickly coated by silicone, reduction of the dilatancy was the most significant.View full abstractDownload PDF (606K) -
Takashi Ogi, Yutaka Kisakibara, I Made Joni, Toru Iwaki, Kikuo Okuyama2013 Volume 50 Issue 6 Pages 421-428
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSThe effects of N-doping on the bead milling dispersion behaviors and optical properties of anatase TiO2 nanoparticles have been investigated and compared with those of bare TiO2. N-doped TiO2 nanoparticles were prepared by mixing anatase powder with urea, and heating the mixture at 800°C for 3 h. The nitrogen elements in the N-doped TiO2 samples were confirmed by Raman analysis. The N-doped TiO2 nanoparticles were then dispersed by bead milling with small beads (15μm) in diglyme using APS as a dispersing agent. The resulting N-doped TiO2 nanoparticles were transparent and colorless suspensions, whereas the dispersed bare TiO2 nanoparticles were yellow. The formation of colorless suspensions by the N-doping process was investigated using a model of the interaction of the N-doped TiO2 surface with the adsorbed dispersant.View full abstractDownload PDF (1068K) -
Takashi Nagai, Takeo Mizobe, Satoru Watano2013 Volume 50 Issue 6 Pages 429-435
Published: June 10, 2013
Released on J-STAGE: June 28, 2013
JOURNAL FREE ACCESSIn this study, novel functional composite particles which have core-shell type structure were made by using surface modification of fine particles via emulsion coating. Spherical cross-linked particles (core particles) which were mainly composed of methyl methacrylate (MMA) having average diameter of 6.8μm and 9.5μm were fed into a high speed air flow field and aqueous-suspended emulsion (cationic surfactant and PMMA of 150 nm were dispersed together) were sprayed onto the core particles, followed by an instantaneous drying to form fine core-shell structure. As a result, a shell layer of thin film having its thickness of 300 nm and coating efficiency of more than 92.7% could be uniformly formed on the surface of the core particles. It was found that the particle diameter could be controlled by changing the amount of emulsion sprayed. It was also implied that the coating operation using emulsion with high glass transition temperature and positive charge could achieve functional composite particles with improved heat tolerance property and positive charge.View full abstractDownload PDF (810K)
Review
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Mamoru Senna2013 Volume 50 Issue 6 Pages 436-446
Published: June 10, 2013
Released on J-STAGE: August 29, 2014
JOURNAL RESTRICTED ACCESSWhen metal oxide fine particles are subjected to mechanical stressing with organic powders such as fluoropolymers or amino acids, oxidative decomposition of organics is catalyzed by the coexisting metallic species, and partial anion exchange in the oxides takes place simultaneously. The phenomena serve as new technology of producing various functional particles with many applications, by utilizing their absorption ability of various photon energies and rational preparation of core-shell particles. Case studies, including nanoparticles of Nb2O5 for smart synthesis of complex oxides for electroceramics, and TiO2 for antibacterial photocatalysis are given, after surveying general needs for fine particle surface modification for the purpose of functionalization.View full abstractDownload PDF (1510K) -
Motoyuki Iijima, Hidehiro Kamiya2013 Volume 50 Issue 6 Pages 447-453
Published: June 10, 2013
Released on J-STAGE: August 29, 2014
JOURNAL RESTRICTED ACCESSControlling the stability of functional particles in various solvents is an essential technique to improve the properties of composite materials comprised from particles. In this review, various examples of wet chemical surface modification protocols on functional hydrophilic oxides and carbon related hydrophobic particles will be introduced to control their stability in various solvents and polymers. For oxide particles, surface modification protocols using silane coupling agents and anionic surfactants will be discussed. For carbon related particles, reactions using azo radical initiators, Diels-Alder reactions, and usage of functionalized polyethyleneimine will be introduced to improve their stability in aqueous media.View full abstractDownload PDF (1019K)
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