Effects of CdCl2 concentration and gamma irradiation on the structural, thermal and electrical conductivity properties of HPMC polymer electrolyte films

Abstract

Solid polymer electrolyte films based on hydroxypropyl methylcellulose (HPMC) with different concentrations of cadmium chloride (CdCl2) were prepared by solution cast method. Different techniques has been employed to investigate the effects of structural, thermal and ionic conductivity behavior of these polymer electrolyte films upon gamma irradiation with different doses of 20, 60 and 100 kGy. The dissolution of the salt into the polymer host and the structural properties of pure and CdCl2 (1% - 4%) (wt. %) complexed HPMC polymer electrolyte films before and after irradiation was confirmed by X - ray diffraction (XRD) studies. XRD results revealed that the amorphous domains of HPMC polymer matrix was increased with increase in the salt concentration and with the gamma dose. The percentage of crystallinity is found to be high in pristine unirradiated HPMC films. The thermal properties of these polymer electrolyte films before and after irradiation were studied using differential scanning calorimetry (DSC). The results revealed that the presence of CdCl2 in the polymer matrix increases the melting temperature, however it is observed that the total enthalpy of fusion ( ) is maximum for unirradiated pristine HPMC films. The variation of film morphology was examined by scanning electron microscopy (SEM). Direct current (dc) conductivity was measured in the temperature range of 313-383K. The magnitude of conductivity was found to increase with increasing concentration of the salt, temperature and for higher dose of radiation. The composition HPMC:CdCl2 (5:4) for unirradiated and irradiated samples, found to exhibit the least crystallanity and the highest conductivity.