Conductivity enhancement in SiO 2 doped PVA:PVDF nanocomposite polymer electrolyte by gamma ray irradiation M. Hema a,⇑ , P. Tamilselvi a,b , P. Pandaram c a Department of Physics, Kamaraj College of Engineering and Technology, Virudhunagar 626001, Tamilnadu, India b Department of Physics, Bannari Amman Institute of Technology, Sathyamangalam 638401, Tamilnadu, India c Kudankulam Nuclear Power Project, Kudankulam, Tamilnadu, India article info Article history: Received 9 December 2016 Received in revised form 12 March 2017 Accepted 20 April 2017 Keywords: Polymer electrolyte Gamma irradiation Ionic conductivity Transference number abstract Nanocomposite polymer electrolyte has been irradiated with 15 Gy Gamma rays. Exposure of gamma radiation caused scissoring and crosslinking of polymer chains thereby increasing amorphous phase of the polymer matrix because of which the ionic conductivity has been enhanced. Ionic conductivity of irradiated nanocomposite polymer electrolyte is enhanced to 9.4  10 4 Scm 1 at 303 K compared to un-irradiated system (r  1.7  10 4 Scm 1 ). Temperature dependence of ionic conductivity of both un-irradiated and irradiated systems obeys VTF relation. Frequency and temperature dependence of dielectric and modulus of both systems have been analyzed. The ionic transference number of polymer electrolyte has been calculated by Wagner’s polarization technique and it confirms that conducting spe- cies are predominantly due to ions in both systems. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction In recent years, solid polymer electrolyte attracts many researchers for its wide range of potential applications in lithium ion batteries, sensors, fuel cells, super capacitors, solar cells [1] because of its excellent properties of size flexibility, light weight, non-flammability, non-leakage [2,3]. For the past few decades, achieving the maximum ionic conductivity at room temperature is the one of the challenging criteria in polymer electrolyte [4]. Hence, different techniques such as blending, plasticization, addi- tion of fillers and ionizing irradiation were used to enhance the properties. However, ionizing radiation is the one of the effective method to enhance the properties of polymer electrolytes. The ion- izing radiation such as X-rays, alpha rays, beta rays and gamma rays causes chemical as well as physical changes in the exposed substance. Recently the researchers investigated that the effect of gamma radiation [5], electron beam radiation [6] and heavy ion radiation [7] on physical and chemical properties of polymer elec- trolyte. Among them, gamma radiation in polymer electrolyte causes chain scission and crosslinking simultaneously [8,9]. It increases the fraction of amorphous region in polymer electrolyte thereby enhancing the ionic conductivity. Literature review shows a very few work on gamma ray irradiation (15 Gy for 1 h) of nanocomposite polymer electrolyte based on PVA and PVDF. The aim of the present work is to study the effect of gamma ray irradiation on the conductivity, dielectric properties of nanocom- posite polymer electrolyte. Hence the optimized system of nanocomposite polymer electrolyte (80PVA:20PVDF:15LiCF 3 - SO 3 :8SiO 2 ) from our earlier work [10] was taken for the present investigation and subjected to gamma ray irradiation. 2. Experimental 2.1. Preparation of nanocomposite polymer electrolyte Poly(vinyl alcohol), PVA (M.w.: 1,25,000) and Poly(vinylidene fluoride), PVDF (M.w.: 5,30,000) were purchased from S. d.Fine, India, Lithium triflate, LiCF 3 SO 3 from Alfa Aesar and N, N- Dimethyl formamide, DMF from Merck, SiO 2 (average particle size  85 nm). The purchased raw materials were used without further purification. Nanocomposite polymer electrolyte (80PVA:20PVDF:15LiCF 3 SO 3 : 8SiO 2 ) has been prepared using solution casting technique. Appropriate quantities of each constituent were separately dis- solved in DMF and stirred at the temperature of 60 °C. The dis- solved polymers and the salt solutions were mixed together and stirred continuously at the same temperature, until homogeneous solution has been obtained. Thus, the obtained solution was casted http://dx.doi.org/10.1016/j.nimb.2017.04.074 0168-583X/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: mhemaphysics@gmail.com (M. Hema). Nuclear Instruments and Methods in Physics Research B 403 (2017) 13–20 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb