Browsing by Author "Huang, Heh-Chang"

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Characterizations of UV-Curable Montmorillonite/Epoxy Nanocomposites Prepared by a Hybrid of Chemical Dispersion and Planetary Mechanical Milling Process
(2012-03-15)
Huang, Heh-Chang
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Huang, Shu-Ping
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Hsieh, Tsung-Eong
;
Chen, Chin-Hsin
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材料科學與工程學系
Ammonium salt, [2-(methacyloyloxy)ethyl] trimethylammonium methyl sulfate (MAOTMA), was adopted to modify montmorillonite (MMT) via the cationic exchange process in an acidic environment and a successful enlargement of MMT lamellar spacing from 1.18 to 1.39 nm was identified by x-ray diffraction and Fourier-transform infrared spectroscopy. Accordingly, UV-curable epoxy nanocomposite resins containing various amounts of MAOTMA-modified MMT were prepared with the aid of a planetary mechanical milling process. Transmission electron microscopy revealed a uniform dispersion of exfoliated MMT lamella in epoxy matrix, leading to the distinct improvements on thermal stability and thermal expansion property of nanocomposite samples. Calcium (Ca) test indicated that the good dispersion of MMT fillers in polymer effectively suppresses the moisture permeation in sample matrix. More than twofold increment on retention time of 5% Ca hydrolysis and 20% improvement on the permeation kinetic parameters were observed in the nanocomposite sample containing 8 wt % MMT in comparison with the pristine epoxy sample. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 3199-3207, 2012
Highly stable precursor solution containing ZnO nanoparticles for the preparation of ZnO thin film transistors
(2010-07-23)
Huang, Heh-Chang
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Hsieh, Tsung-Eong
;
材料科學與工程學系
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Department of Materials Science and Engineering
ZnO particles with an average size of about 5 nm were prepared via a sol-gel chemical route and the silane coupling agent, (3-glycidyloxypropyl)-trimethoxysilane (GPTS), was adopted to enhance the dispersion of the ZnO nanoparticles in ethyl glycol (EG) solution. A ZnO surface potential as high as 66 mV was observed and a sedimentation test showed that the ZnO precursor solution remains transparent for six months of storage, elucidating the success of surface modification on ZnO nanoparticles. The ZnO thin films were then prepared by spin coating the precursor solution on a Si wafer and annealing treatments at temperatures up to 500 degrees C were performed for subsequent preparation of ZnO thin film transistors (TFTs). Microstructure characterization revealed that the coalescence of ZnO nanoparticles occurs at temperatures as low as 200 degrees C to result in a highly uniform, nearly pore-free layer. However, annealing at higher temperatures was required to remove organic residues in the ZnO layer for satisfactory device performance. The 500 degrees C-annealed ZnO TFT sample exhibited the best electrical properties with on/off ratio = 10(5), threshold voltage = 17.1 V and mobility (mu) = 0.104 cm(2) V(-1) s(-1).
Preparation and characterizations of highly transparent UV-curable ZnO-acrylic nanocomposites
(2010-05-01)
Huang, Heh-Chang
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Hsieh, Tsung-Eong
;
材料科學與工程學系
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Department of Materials Science and Engineering
A sol gel chemical route was adopted to prepare the zinc oxide (ZnO) nanoparticles as small as 4 nm. UV-curable ZnO-acrylic nanocomposites were then prepared by employing 3-(trimethoxysilyl)propyl methacrylate (TPMA) as the surface modification agent of ZnO particles. UV-vis analysis revealed a high optical transparency (>95%) in visible light region for nanocomposite thin films with ZnO contents up to 20 wt.%. The addition of ZnO nanoparticles also enhanced the dielectric constants of nanocomposites and the dielectric constants greater than 4 in frequencies ranging from 1 to 600 MHz was obtained in the samples containing 10 wt.% of ZnO nanoparticles. A comparison of experimental results and theoretical calculation indicated that the interfacial polarizations in between ZnO nanoparticles and polymer matrix may play an important role in the enhancement of dielectric properties of nanocomposites. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Preparation and Characterizations of Tantalum Pentoxide (Ta(2)O(5)) Nanoparticles and UV-Curable Ta(2)O(5)-Acrylic Nanocomposites
(2010-08-05)
Huang, Heh-Chang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Tantalum pentoxide (Ta(2)O(5)) nanoparticles with the sizes in the range of 20-50 nm were prepared via a chemical route in which the oleic acid (OLEA) was adopted as the surfactant for the synthesis process. X-ray diffraction (XRD) revealed the as-synthesized Ta(2)O(5) transforms from amorphous to hexagonal and ortho-rhombic structures at the temperatures of 700 degrees C and 750 degrees C, respectively, illustrating the suppression of recrystallization temperature of Ta(2)O(5) due to the particle size reduction. UV-curable nanocomposites containing the Ta(2)O(5) nanoparticles and acrylic matrix were also prepared. Thermogravimetry analysis (TGA) found an about 10-20 degrees C improvement on the 5% weight-loss thermal decomposition temperatures (T(d)s). Dielectric measurement showed that the dielectric constant of nanocomposite increases with the increase in the filler loading without severe deterioration of dielectric loss. The increment of dielectric constants was ascribed to the addition of high-dielectric inorganic fillers as well as the presence of interfacial polarization at the organic/inorganic interfaces. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1252-1259, 2010
Preparation and Characterizations of Tantalum Pentoxide (Ta2O5) Nanoparticles and UV-Curable Ta2O5-Acrylic Nanocomposites
(2010-08-05)
Huang, Heh-Chang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Tantalum pentoxide (Ta2O5) nanoparticles with the sizes in the range of 20-50 nm were prepared via a chemical route in which the oleic acid (OLEA) was adopted as the surfactant for the synthesis process. X-ray diffraction (XRD) revealed the as-synthesized Ta2O5 transforms from amorphous to hexagonal and ortho-rhombic structures at the temperatures of 700 degrees C and 750 degrees C, respectively, illustrating the suppression of recrystallization temperature of Ta2O5 due to the particle size reduction. UV-curable nanocomposites containing the Ta2O5 nanoparticles and acrylic matrix were also prepared. Thermogravimetry analysis (TGA) found an about 10-20 degrees C improvement on the 5% weight-loss thermal decomposition temperatures (T(d)s). Dielectric measurement showed that the dielectric constant of nanocomposite increases with the increase in the filler loading without severe deterioration of dielectric loss. The increment of dielectric constants was ascribed to the addition of high-dielectric inorganic fillers as well as the presence of interfacial polarization at the organic/inorganic interfaces. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1252-1259, 2010