**2.3 Polymer blending**

Polymer blending is physical means to mix two or more different polymers or copolymers which are not linked by covalent bonds. This polymer blend is a new macromolecular material with special combinations of properties. For polymer blends, a first phase is adopted to absorb the electrolyte active species, whereas the second phase is tougher and sometimes substantially inert. It is a feasible way to increase the ionic conductivity because it offers the combined advantages of ease of preparation and easy control of physical properties within the definite compositional change (Rajendran et al., 2002). Polymer blending is of great interest due to their advantages in properties and processability compared to single component. In industry area, it enhances the processability of high temperature or heat–sensitive thermoplastic in order to improve the impact resistance. Besides, it can reduce the cost of an expensive engineering thermoplastic. The properties of polymer blends depend on the physical and chemical properties of the participating polymers and on the state of the phase, whether it is in homogenous or heterogeneous phase. If two different polymers able to be dissolved successfully in a common solvent, this polymer blends or intermixing of the dissolved polymers will occur due to the fast establishment of the thermodynamic equilibrium (Braun, 2005). Sivakumar et al. (2006) observed that PVA (60 wt%)–PMMA (40 wt%)–LiBF4 complex exhibits the maximum conductivity of 2.8×10−5 Scm−1 at ambient temperature. It is also higher than the pure PVA system which has been reported to be 10−10 Scm−1.
