Investigation on Solid Polymer Electrolyte ( SPE ) Membrane of Composition [ ( 1X ) PEO : x AgCl ] Prepared by Hot Press Technique

Solid polymer Electrolyte (SPE ) is prepared by using PEO as host polymer and AgCl as salt in appropriate wt% ratio of the composition [(1-X) PEO: x AgCl ] where X = 10, 20, 30, 40 etc.by novel hot press technique. For ion transport property study conductivity (σ) measurement is done for various composition x in (wt %) and the composition [70 PEO: 30AgCl] is identified as optimum conducting composition (OCC). The variation in conductivity as a function of temperature is analysed and activation energy (Ea) is computed be least square fitting of the data of conductivity with respect to temperature. The conductivity enhancement of more than one order is obtained in SPE (OCC) as compare to pure PEO. The morphological and structural characterization of SPE membrane is done by using XRD/DSC, SEM, and FTIR studies.

In physical modification methods morphology and phase structure of polymer electrolytes can be changed by incorporating a suitable plasticizer or organic/inorganic filler which either introduces flexibility in polymeric chain or creates amorphous cell with defectation around dispersed grains 5 .The addition of small organic/ inorganic or inert fillers decreases the crystallinity and enhances amorphousity of system 6 .The conductivity of polymer electrolytes is affected by grain size distribution, particle concentration, surface area and phase structucture.Higher conductivity can be obtained by using nanosize fillers, which are much more prone to agglomeration than microsize fillers 7 .
Composite electrolytes are prepared adopting various procedures depending upon types of fillers and the form of polymeric material 8 .Most of the researcher uses solution cast method for the preparation of polymer composite.A solvent free dry method known as hot press technique 9 is recently being used for the preparation of polymeric membrane.This technique is quicker as well as cost effective 10 .
The present paper reports the casting of Ag + ion conducting SPE membrane [(1-x) PEO: xAgCl] by novel hot press technique.The conductivity of SPE membrane for various compositions is measured.The transport properties are studied with the help of ionic conductivity (σ) at room temperature.The morphological characterization is done with the help of XRD, SEM and FTIR study.For the thermal characterization DSC is done.

EXPERIMENTAL Material preparations
For the casting of Ag + ion conducting solid polymer electrolyte (SPE) membrane [(1-x) PEO: x AgCl] where x=10, 20, 30, 40 etc in (wt%) ratio solvent free / dry hot press technique is used.For the casting of membrane precursor grade chemicals PEO poly(ethylene oxide) (10 6 Mw, Aldrich, USA) and silver chloride AgCl (purity>99%, Reidel Lab Reagent) are used.Powders of constituent chemicals in appropriate (wt %) ratio is homogeneously mixed for 30 min in an agate pestle & mortar at room temperature.Finely grounded mixture of different compositions is heated separately nearly at temperature~ 70 o C (close to melting point of PEO) with continuously mixing for 20 minutes.The soft slurry so obtained is then pressed between two cold SS-blocks (~ 1.25 tons/ cm 2 ) which give rise to film of uniform thickness 0.035 cm.

Conductivity (σ σ σ
σ σ) measurement Conductivity (σ) measurements are carried out on samples of different composition by keeping them between two non blocking silver electrodes at fixed frequency (~ 1kHz) using LCR Bridge (ESCORT , ELC-131D, TAIWAN).Activation energy (E a ) was determined by least square fitting of conductivity data obtained at different temperature and for all the compositions of SPE membrane.

Material characterization studies
For the phase identification of SPE (OCC) XRD is used.For thermal analysis of the specimen DSC is used.For structural and morphological characterization SEM study is performed.

Measurement of Ionic conductivity (σ σ σ σ σ) as a function of salt concentration and temperature
Figure1 depicts the salt concentration dependent room temperature conductivity (σ) of solid polymer electrolyte (SPE) membrane [(1-x) PEO: xAgCl] where x is take as 10, 20, 30, 40 in wt % ratio.From the figure it is clear that ionic conductivity increases gradually with the increase in salt concentration (x) in wt % ratio it attains maximum value for x=30(wt %)of salt concentration and then starts decreasing with further increase in salt concentration.The maximum conductivity (σ) obtained for x= 30 wt % of salt concentration is optimum conducting composition (OCC) of the SPE membrane.The SPE film beyond 50(wt %) ratio of salt concentration becomes less stable, brittle and sticky.The SPE membrane of composition [70PEO:30AgCl] with room temperature conductivity of (σ = 1.6×10 -8 S/cm) with (σ) enhancement of approximately one order of magnitude can be seen as compare pure PEO (polymeric host).  of pure PEO, XRD patterns of SPE (OCC) exhibits appearance of some of the prominent peaks which are diminished and shifted toward higher 2è side reflecting characteristic features of semicrystalline/ amorphous polymers [11][12] .

Fig. 2 Fig. 2 :
Fig. 2 depicts the temperature dependence of Ionic conductivity (logσ-1000/T) of SPE membrane.The behavior is typical Arrhenius behavior described by Fig.