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Poly(vinylidene fluoride-hexafluropropylene) (PVDF-HFP) and poly(methyl methacrylate) (PMMA)-based gel polymer electrolytes (GPEs) comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of lithium perchlorate (LiClO 4 ) salt concentrations have been prepared using a solvent casting technique. Structural characterization has been carried out using XRD wherein diffraction pattern reveals the amorphous nature of sample up to 7.5 wt.% salt and complexation of polymers and salt have been studied by FTIR analysis. Surface morphology of the samples has been studied using scanning electron microscope. Electrochemical impedance spectroscopy in the temperature range 303-363 K has been carried out for electrical conductivity. The maximum room temperature conductivity of 2.83Â10 À4 S cm À1 has been observed for the GPE incorporating 7.5 wt.% LiClO 4 . The temperature dependence of ionic conductivity obeys the Arrhenius relation. The increase in ionic conductivity with change in temperatures and salt content is observed. Transport number measurement is carried out by Wagner's DC polarization method. Loss tangent (tan ) and imaginary part of modulus (M 00 ) corresponding to dielectric relaxation and conductivity relaxation respectively show faster relaxation process with increasing salt content up to optimum value of 7.5 wt.% LiClO 4 . The modulus (M 00 ) shows that the conductivity relaxation is of non-Debye type (broader than Debye peak).

This article discusses a simplified approach to analyze mechanical properties of randomly distributed short fiber composites. Mechanical properties of three different randomly oriented short fiber composites, cotton, nylon, and aluminium with vinylester resins, were experimentally investigated. The analytical results were compared with experimental results and a very good correlation was found. Further, the experimental results and the predictions showed that the strength of the composites is less than the strength of the matrix material, for all three composites tested.

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To overcome the drawbacks of organic solvent−based liquid electrolytes and a solid polymer electrolyte as a separator in lithium polymer battery, in the recent study gel polymer electrolyte (GPE) using poly(vinylidene fluoride− hexafluropropylene) (PVDF−HFP) and poly (methyl methacrylate) (PMMA) as host polymers, lithium perchlorate (LiClO 4 ) salt as conducting species and propylene carbonate (PC) and diethyl carbonate (DEC) plasticizers as an organic solvent has been prepared. The solution casting technique has been adopted to fabricate gel polymer electrolyte (GPE). The prepared GPE films were analyzed using different experimental techniques to discover the properties of GPE. The ionic conductivity of GPE films has been carried out using electrochemical impedance spectroscopic technique. The maximum ionic conductivity of 3.97E-4 S cm −1 has been obtained for GPE having 60 wt% PC:DEC. As an evidence of change in ionic conductivity, structural characterization has been analyzed using FTIR and SEM where, FTIR spectra reveal complex formation taking place between polymers, salt, and plasticizers and SEM micrograph shows a change in surface morphology with a change in plasticizers amount. Dielectric analysis has been also carried out in terms of dielectric constant (e¢) and dielectric loss (e). Cyclic voltammetry (CV) has been applied to find electrochemical stability window.

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