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排序方式: 共有372条查询结果,搜索用时 31 毫秒
31.
K. Dinesh Kumar Andy H. Tsou Anil K. Bhowmick 《Journal of Polymer Science.Polymer Physics》2010,48(9):972-982
The effects of change in surface energy and bulk viscoelastic properties on the autohesive tack strength of brominated isobutylene‐co‐p‐methylstyrene (BIMS) rubber have been investigated by the addition of hydrocarbon resin (HCR) tackifier and maleated hydrocarbon resin (MA‐g‐HCR) tackifier. The addition of compatible HCR tackifier results in a reasonable increment in the tack strength of BIMS rubber by modifying only the bulk viscoelastic properties (compliance, entanglement molecular weight, relaxation time, self‐diffusion, and monomer friction coefficient values) of BIMS rubber to perform better during the course of bonding and debonding steps of the peel test. Incorporation of MA‐g‐HCR tackifier (containing 5–20 wt % of grafted maleic anhydride) steadily increases the tack strength of BIMS rubber further by precisely modifying both the surface energy and bulk viscoelastic properties to perform much better in the bonding and debonding steps. However, beyond 20 wt % of grafted maleic anhydride in the HCR tackifier, the tack strength starts decreasing due to the incompatibility between the blend components, and hence, the bulk viscoelastic properties required for bond formation are severely retarded by the interrelated reinforcing effect and the phase separation effect of the brittle MA‐g‐HCR tackifier in the BIMS rubber. Hence, the polar groups in a tackifier will contribute to significant enhancement of autohesive tack strength only if the bulk viscoelastic property of the rubber‐tackifier blend is favorable for bond formation and bond separation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 972–982, 2010 相似文献
32.
Jian Zhang Tian-Qi Zhao Yao Chen Xiao-Dong Chen Hai-Kun Chang Yu-Min Zhang Shu-Cheng Hua 《Chemical Papers》2015,69(2):325-338
A solvent-free microwave-assisted method for the synthesis of 2-substituted-4,5-di(2-furyl)-1H-imidazoles was developed. Imidazoles with moderate to good yields were produced by condensation of furil with aldehydes over acidic alumina impregnated with ammonium acetate, and they were characterized by FT-IR, HRMS, 1H NMR and 13C NMR spectroscopy. Crystal structure of 2,4,5-tri-2-furyl-1H-imidazole (I) in the orthorhombic space group Pbca was reported, which showed more coplanarity than the reported crystal structure of I in the monoclinic space group Cc. Moreover, their luminescent properties were investigated. It was found that the organic small molecule compounds synthesized possess higher fluorescence quantum efficiency (up to 0.508) in a 0.1 M H2SO4 aqueous solution dissolved in 0.5 mL of CH3OH; along with higher stability; also the emission of some compounds synthesized in the solution was sensitive to the polarity of the solvents. 相似文献
33.
Thermophysical properties of pure 1-ethyl-3-methylimidazolium methylsulphate and its binary mixtures with alcohols 总被引:1,自引:0,他引:1
Jian-Ying WangFeng-Yun Zhao Yu-Min LiuXiao-Ling Wang Yong-Qi Hu 《Fluid Phase Equilibria》2011,305(2):114-120
The density and surface tension of 1-ethyl-3-methylimidazolium methylsulphate, [EMIM][CH3SO4] ionic liquid have been measured from (283.15 to 333.15) K. The coefficient of thermal expansion was calculated from the experimental density results using an empirical correlation for T = (283.15-338.15) K. Molecular volume and standard entropies of [EMIM][CH3SO4] ionic liquid were obtained from the experimental density values. The surface properties, critical temperature and enthalpy of vaporization were also discussed. Density and surface tension have been measured over the whole composition range for [EMIM][CH3SO4] with alcohols (methanol, ethanol, 1-butanol) binary systems at 298.15 K and atmospheric pressure. Excess molar volumes and surface tension deviations for the binary systems have been calculated and were fitted to a Redlich-Kister equation to determine the fitting parameters and the root mean square deviations. 相似文献
34.
Killgore JP Yablon DG Tsou AH Gannepalli A Yuya PA Turner JA Proksch R Hurley DC 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):13983-13987
We demonstrate the accurate nanoscale mapping of near-surface loss and storage moduli on a polystyrene-polypropylene blend with contact resonance force microscopy (CR-FM). These viscoelastic properties are extracted from spatially resolved maps of the contact resonance frequency and quality factor of the AFM cantilever. We consider two methods of data acquisition: (i) discrete stepping between mapping points and (ii) continuous scanning. For point mapping and low-speed scanning, the values of the relative loss and storage modulus are in good agreement with the time-temperature superposition of low-frequency dynamic mechanical analysis measurements to the high frequencies probed by CR-FM. 相似文献
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Monopole charges, being global quantities, depend on the gauge group of a theory, which in turn is determined by the representations of all its fields. For example, chromodynamics in its present form when combined with electrodynamics has as its gauge group not SU(3) × U(1) but a “smaller” group U(3). The specification of monopole charges for a theory can thus be quite intricate. We report here the result of an investigation in several current gauge theories. Of particular interest is the possible existence in some theories of monopoles carrying multiplicative charges. As a by-product, we clarify some earlier assertions in the literature which seem to us incorrect. 相似文献
38.
Luminol-Cu(Ⅱ)体系流动注射化学发光法测定乙酰半胱氨酸 总被引:1,自引:0,他引:1
发现了Luminol-Cu(Ⅱ)-乙酰半胱氨酸化学发光体系,探讨了影响化学发光反应的各个因素,建立了测定乙酰半胱氨酸的流动注射化学发光新方法。该方法的线性范围为7.0×10-10—1.0×10-7g/mL,检出限为2.0×10-11g/mL,相对标准偏差为1.0%(1.0×10-8g/mL,n=11)。该方法已用于药物制剂中乙酰半胱氨酸含量的测定。 相似文献
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This paper theoretically investigates three stochastic systems with cross-correlation Gaussian white noises.Both steady state properties of the stochastic nonlinear systems and the nonequilibrium transitions induced by the cross-correlated noises are studied.The stationary solutions of the Fokker-Planck equation for three specific examples are analysed.It is shown explicitly that the cross-correlation of white noises can induce nonequilibrium transitions. 相似文献