1. Introduction Use of nanoparticles in numerous applications has become a major area of interdisciplinary research in recent times. The method of nanoparticle synthesis is an important factor in determining the type of ap- plication. The research, particularly on semiconduc- tor nanoparticles is motivated by its possible uses in various fields like nonlinear optics, solar cells, light- emitting devices, electronics, biological labels, and catalysis. The size-dependent mechanical, optical and electronic properties are very much essential. When a particle approaches the size of a few nanometers, its diameter becomes equal to or less than the bulk semiconductor exciton diameter (for cadmium sul- fide it is 5–6 nm [1]), such that quantum confinement of electron-hole pairs increase the band gap relative to that in the bulk materials. Hence, the control of particle size allows tuning of the band gap which gives the desired above mentioned electronic and op- tical properties. Reinforcement of inorganic nanopar- ticles inside solid polymer matrices are attracting in- creased attention because the combination of both these materials provides a simple route to stable and processable materials having properties of both com- ponents incorporated in the matrix [1]. However, these composites normally cannot be re-dis- solved while protecting the colloidal state of nanopar- ticles. The single polymer molecule represents an im- portant type because isolated nanocomposites based on a single molecule can be obtained, which have very desirable processing characteristics. Mainly, all the applications which are based on single polymer mol- ecule can be applied to the single molecule-nanopar- ticle composites also. In most of these cases, the nano- 883 Influence of cadmium sulfide nanoparticles on structural and electrical properties of polyvinyl alcohol films J. Koteswararao 1 , R. Abhishek 1 , S. V. Satyanarayana 2 , G. M. Madhu 1* , V. Venkatesham 1 1 Department of Chemical Engineering, M S Ramaiah Institute of Technology, 560054 Bangalore, Karnataka, India 2 Department of Chemical Engineering, Jawaharlal Nehru Technological University Anantapur, Anantapuramu – 515002, Andhra Pradesh, India Received 1 January 2016; accepted in revised form 20 June 2016 Abstract. Cadmium sulfide (CdS) nanoparticles have been synthesized by hydrothermal method and dispersed in poly vinyl alcohol (PVA) matrix in varying amounts by weight. Subsequently, PVA/CdS nanocomposites have been synthesized with the objective of investigating the effect of CdS nanoparticles on structural and electrical properties of PVA films. Structural properties were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Differential scanning calorimetry (DSC) was used to investigate thermal properties of PVA/CdS nanocomposites. Electrical properties were measured by using high frequency LCR meter and were found to be strongly dependent on frequency and nano CdS content. Dielectric constant decreased with increase in frequency and with increase in nanofiller concentration. AC conductivity and dielectric loss increased with frequency and decreased with increase in nano CdS content. Keywords: nanocomposites, cadmium sulfide, electrical properties, polyvinyl alcohol eXPRESS Polymer Letters Vol.10, No.11 (2016) 883–894 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2016.83 * Corresponding author, e-mail: gmmadhu@gmail.com © BME-PT