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Browsing by Author "WHANG, WT"

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    EFFECT OF POLY(VINYLIDENE FLUORIDE) ON THE IONIC-CONDUCTIVITY AND MORPHOLOGY OF PEO-SALT POLYMER ELECTROLYTES
    (1994-11-14)
    WHANG, WT
    ;
    YANG, LH
    ;
    FAN, YW
    ;
    交大名義發表
    ;
    材料科學與工程學系
    The high dielectric constant polymer poly (vinylidene fluoride) (PVDF) was blended with PEO-salt polymer electrolytes to improve their ionic conductivity. PVDF did improve the room-temperature ionic conductivity of the polymer electrolytes PEO-LiCF3CO2 and PEO-LiBF4, and the ionic conductivity at room temperature went up one order of magnitude with 10(-5)S/cm for LIB4M-PF4 being the most prominent. PVDF exhibited strong effects on the ionic conductivity and morphology of the polymer electrolytes, such as weakening the association of poly (ethylene oxide) (PEO) with the salt, hindering the formation of the PEO-salt complex, enlarging the crystalline PEO phase in LIAnM-PFm polymer electrolytes, and reducing the crystalline PEO phase in LIBnM-PFm polymer electrolytes. Both LIA4M-PF4 and LIB4M-PF4 polymer electrolytes formed a new PEO-PVDF-salt complex. The new complex in the former was crystalline, but that in the latter was amorphous. (C) 1994 John Wiley and Sons, Inc.
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    EFFECTS OF POLYMER MATRIX AND SALT CONCENTRATION ON THE IONIC-CONDUCTIVITY OF PLASTICIZED POLYMER ELECTROLYTES
    (1995-06-20)
    WHANG, WT
    ;
    LU, CL
    ;
    交大名義發表
    ;
    材料科學與工程學系
    ;
    National Chiao Tung University
    Two polar polymers with different dielectric constants, poly(vinylidene fluoride) (PVDF) and poly (ethylene oxide) (PEG), were each blended with a chlorine-terminated poly(ethylene ether) (PEG) and one of the two salts, LiBF4 and LiCF3CO2, to form PEC-plasticized polymer electrolytes. The room-temperature ionic conductivity of the PEC-plasticized polymer electrolytes reached a value as high as 10(-4) S/cm. The room-temperature ionic conductivity of the PVDF-based polymer electrolytes displayed a stronger dependence on the PEC content than did the PEG-based polymer electrolytes. In PVDF/PEC/LiBF4 polymer electrolytes, the dynamic ionic conductivity was less dependent on temperature and more dependent on the PEC content than it was in PEO/PEC/LiBF4 polymer electrolytes. The highly plasticized PVDF-based polymer electrolyte film with a PEC content greater than CF4 (CF4 defined as the molar ratio of the repeat units of PEC to those of PVDF equal to 4) was self-supported and nonsticky, while the corresponding PEG-based polymer electrolyte film was sticky. In these highly plasticized PVDF-based polymer elec trolytes, the curves of the room-temperature ionic conductivity vs. the salt concentration were convex because the number of carrier ions and the chain rigidity both increased with increase of the salt content. The maximum ionic conductivity at 30 degrees C was independent of the PEC content, but it depended on the anion species of the lithium salts in these highly plasticized polymer electrolytes. (C) 1995 John Wiley and Sons, Inc.
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    ELECTROOPTIC CHARACTERISTICS OF AMINO-GEL-GLASS-DISPERSED LIQUID-CRYSTAL AND ITS MATRIX FORMATION
    (1995-04-01)
    CHANG, WP
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    WHANG, WT
    ;
    WONG, JC
    ;
    材料科學與工程學系
    ;
    Department of Materials Science and Engineering
    The gel-glass-dispersed liquid crystals (GDLCs) from amino-silicon alkoxides have successfully been prepared in a short time by sol-gel process. Those GDLCs had the same operation mechanism and performances as polymer-dispersed liquid crystal(PDLC). The electrooptic characteristic of the GDLC strongly depended on the composition of raw materials and the concentrations of liquid crystal. Titanium ethoxide was used successfully to adjust the refractive index of the gel-glass matrix, but it caused the gel-glass to be less flexible and the GDLC operated at a higher voltage. GDLC-13 had a reasonable operation voltage of 13 V, a good on-state transmittance of 100%, and a good contrast of 16.2. The introducing of a two-functional amino silane, (3-[diethoxymethylsilyl] propylamine), in the composition of matrix raw materials offered the gel-glass matrix better flexibility, higher conductivity, and greater capacity for trapping liquid crystal. It resulted in a significant improvement of the electrooptic characteristic of the GDLC
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    INTERFACIAL CHARACTERISTICS OF HIGH-PERFORMANCE CARBON-FIBER THERMOPLASTIC COMPOSITES WITH POLYIMIDE COUPLING AGENTS
    (1990-10-01)
    WHANG, WT
    ;
    LIU, WL
    ;
    交大名義發表
    ;
    材料科學與工程學系
    ;
    National Chiao Tung University
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    THE EFFECT OF PREPARATION PROCESS OF PMDA-ODA-DR1 POLYIMIDE ON ITS 2ND-HARMONIC GENERATION CHARACTERISTICS
    (1995-06-20)
    CHANG, CJ
    ;
    WHANG, WT
    ;
    HUANG, JY
    ;
    LIAO, CL
    ;
    LIU, JM
    In situ second harmonic generation (SHG) observation of PMDA-ODA-DR1 polyimide films prepared by different preparative procedures were studied to understand the effects of the residual acid and the imidization byproduct and the extent of imidization on the SHG characteristics of the PMDA-ODA-DR1 polyimides. PMDA-ODA-DR1 polyimides with or without removal of salt were also investigated to study the influence of remaining triethyl hydrogen ammonium chloride salt on the SHG characteristics and reliability of the polymers. A blue shift in the UV/vis spectrum during poling was observed for the low-temperature-baked film, but did not occur for the high-temperature-baked film. Both high-temperature imidization and removal of the byproduct organic salt did not only improve the poling efficiency of PMDA-ODA-DR1 polyimide as a SHG material, but also slowed down the relaxation of the film and made the film more reliable. (C) 1995 John Wiley and Sons, Inc.
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    THERMAL-STABILITY OF 2ND-ORDER NONLINEARITY IN POLED POLYMERIC FILMS
    (1995-01-01)
    HUANG, JY
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    LIAO, CL
    ;
    WHANG, WT
    ;
    CHANG, CJ
    ;
    材料科學與工程學系
    The thermal stability of the poled polar order of nonlinear optical (NLO) chromophores covalently appended to the main chain of polymeric films was studied by measuring the generated optical second-harmonic signal over a wide range of temperatures. Our results provide insight into the relationship of the thermal stability of the poled order with chemical bonding and elastic interaction of the NLO chromophores in polymeric matrices.