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1.
The proton-conducting gel electrolytes based on poly(methyl methacrylate) (PMMA) doped by acid solutions in aprotic solvents were synthesized and discussed in this work. The gel conductivity as a function on concentrations of acid and polymer as well as of molecular mass of PMMA has been analyzed. The thermal stability of electrolytes was estimated and discussed. Extreme dependence of the conductivity on concentration is found to be for the gel (at a concentration of PMMA from 5 to 15 wt.%). The increase of electrical conductivity in the concentration range from 5 to 10 wt.% of PMMA with an increase in viscosity of the system is discussed as an indication of an involvement of the polymer matrix in increasing the mobility of the charge carriers in frame of Grotthuss mechanism.  相似文献   

2.
The thermal conductivity of nanoliquids has been simulated by molecular dynamics method. We consider nanofluids based on argon with aluminum and zinc particles with sizes of 1–4 nm. The volume concentration of nanoparticles is varied from 1 to 5%. The dependence of the thermal conductivity on the volume concentration of nanoparticles has been analyzed. It has been shown that the thermal conductivity of a nanofluid cannot be described by classical theories. In particular, it depends on the particle size and increases with it. However, it has been established that the thermal conductivity of nanofluids with small particles can even be lower than that of the carrier fluid. The behavior of the correlation functions responsible for the thermal conductivity has been studied systematically, and the reason for the increase in the thermal conductivity of nanofluid has been explained qualitatively.  相似文献   

3.
The lithium salt (x) (x=LiAsF6, LiPF6) was complexed with a blend of poly(vinyl chloride) (PVC) / poly(methyl methacrylate)(PMMA) and plasticized with a combination of ethylene carbonate(EC) and propylene carbonate(PC). The electrolyte films were prepared using doctor blade method and subjected to ionic conductivity measurements at nine different temperatures viz.,-30, -15, 0, 15, 30, 40, 50, 60 and 70 °C. The films were also subjected to TG - DTA and FT-IR analysis. The effect of salt on ionic conductivity is discussed. A 75:25 PMMA/PVC blend at 60 % plasticizer content has been found to possess optimal properties in terms of ionic conductivity, thermal and electrochemical stability.  相似文献   

4.
In this paper, a new and simple approach for in-situ preparation of transparent ZnO/poly(metyl methacrylate) (ZnO/PMMA) nanocomposite films was developed. Poly(methyl methacrylate)-co-poly(zinc methacrylate acetate) (PMMA-co-PZnMAAc) copolymer was synthesized via free-radical polymerization between methyl methacrylate (MMA) and zinc methacrylate acetate (ZnMAAc), where asymmetric ZnMAAc with only one terminal double bond (C=C) was applied to act as the precursor for ZnO nanocrystals and could avoid cross-link. Subsequently, transparent ZnO/PMMA nanocomposite films were obtained by in-situ thermal decomposition. Scanning electron microscope (SEM) image revealed that ZnO nanocrystals were homogeneously dispersed in PMMA matrix. With thermal decomposition time increasing, the absorption intensity in UV region and photoluminescence intensity of ZnO/PMMA nanocomposite films enhanced. However, the optical properties diminished when the thermal decomposition temperature increased. The TGA measurement displayed ZnO/PMMA nanocomposite films prepared by the in-situ synthesis method possessed better thermal stability compared with those prepared by the physical blending method and pristine PMMA films.  相似文献   

5.
A new class of gel polymer electrolytes comprising the blend of poly(ethyl methacrylate) (PEMA) and poly(vinylidene fluoride), the mixture of ethylene carbonate and propylene carbonate as a plasticizer, and lithium perchlorate (LiClO4) as a salt was prepared using solvent casting technique. The formation of polymer–salt complexes has been confirmed by XRD analysis. Morphological and thermal studies have been performed using SEM and DMA analyses. A comparative look between PEMA and poly(methyl methacrylate) (PMMA) electrolytes has showed that PEMA electrolytes exhibited better electrochemical performances than PMMA electrolytes, despites its lower conductivity.  相似文献   

6.
The thermal conductivity and heat capacity of manganese-doped zinc oxide polycrystals have been studied in the temperature range 30–300 K. A substantial influence of the secondary phase or MnO clusters formed as a result of doping on the temperature dependences of thermophysical properties of polycrystalline zinc oxide films has been shown.  相似文献   

7.
PMMA based protonic polymer gel electrolytes   总被引:1,自引:0,他引:1  
The paper reports the synthesis of protonic polymer gel electrolytes containing different hydroxy benzoic acids (ortho-, meta- and para-) and aliphatic dicarboxylic acids. Gel electrolytes were prepared by adding polymethylmethacrylate (PMMA) in different weight ratios to the 1M solution of above acids in a ternary solvent mixture of propylene carbonate (PC), ethylene carbonate (EC) and dimethylformamide (DMF) in equal volume ratio. The conductivity of these gel electrolytes has been found to depend upon the amount of PMMA added to the system. A “Breathing Polymeric Chain Model” has been proposed to explain the variation of conductivity with PMMA concentration in these gel electrolytes.  相似文献   

8.
The addition of polymethyl methacrylate (PMMA) having different molecular weights to electrolytes containing ammonium trifluoromethanesulfonate (NH4CF3SO3) in diethyl carbonate (DEC) has been found to result in conductivity enhancement and to yield gel electrolytes with conductivity higher than the corresponding liquid electrolytes. The increase in conductivity has been found to be due to the dissociation of undissociated NH4CF3SO3 and ion aggregates present in the electrolytes, and this has been supported by Fourier transform infrared spectroscopy results, which suggests active interaction of PMMA and NH4CF3SO3 in these gel electrolytes. The increase in conductivity also depends upon the molecular weight of the polymer used and is relatively more for PMMA having lower molecular weight. The increase in viscosity with PMMA addition also depends upon the molecular weight of the polymer and is closely related to the conductivity behavior of these electrolytes. Polymer gel electrolytes have been found to be thermally stable up to a temperature of 125 °C.  相似文献   

9.
Although a large number of ionic conductors based on poly(methyl-methacrylate) (PMMA) are reported in literature, an optimization of salt concentration with respect to conductivity and stability properties remains by and large neglected. We report, perhaps for the first time, such an optimization of salt (LiClO4) concentration on structural, morphological, electrical, and ion–polymer interaction in PMMA-based solid polymer films. The active coordination site for the cation (Li+), out of the two possible electron donating functional groups (i.e. C=Ö and Ö–CH3) in PMMA, has been ascertained on the basis of evidences recorded in Fourier transform infrared spectrum. The results suggested C=Ö as the only possible site in PMMA matrix for coordination with Li+ cation. The X-ray diffraction results have clearly indicated an optimum limit of salt dissolution in PMMA matrix corresponding to O/Li = 4 (i.e., ~21wt.%) above which “phase-separation” occurs distinctly. The effect of salt concentration on amorphous → crystalline phase changes in PMMA and its correlation to morphology have been clearly observed in terms of their impact on electrical properties. An optimum electrical conductivity of ~7.2 × 10?5S cm?1 has been recorded at 100°C (~PMMA glass transition). The temperature dependence of conductivity follows typical Vogel–Tamman–Fulcher behavior.  相似文献   

10.
S. Ramesh  K. C. Wong 《Ionics》2009,15(2):249-254
Thin films of poly(methyl methacrylate) (PMMA) with lithium triflate (LiCF3SO3) were prepared by using the solution-casting method with PMMA as the host polymer. Ionic conductivity and dielectric measurements were carried out on these films. The highest conductivity for polymer electrolyte with a ratio of 65:35 was found to be 9.88 × 10−5 S cm−1, which is suitable for the production of mobile phone battery. Thermal gravimetric analysis was carried out to evaluate the thermal stability of the polymer electrolyte. The addition of salts will increase thermal stability of the polymer electrolyte.  相似文献   

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