Solvent induced miscibility between polymers, and its influence on the morphology, and mechanical properties of their blends Zafarullah Khan Marwat ⇑ , Musa Kaleem Baloch Department of Chemistry, Gomal University, Dera Ismail Khan, Pakistan article info Article history: Received 6 November 2014 Received in revised form 21 February 2015 Accepted 23 February 2015 Available online 4 March 2015 Keywords: Solvent effects on the miscibility PS + PSAN blend Morphology Differential scanning calorimetry (DSC) Thermogravimetric analysis (TGA) Mechanical properties abstract Solvent dependent miscibility, morphology, thermal, and mechanical behavior of polystyr- ene (PS) + poly (styrene-co-acrylonitrile) (PSAN) blend films cast from dimethyl form amide (DMF), and chloroform (CHCl 3 ) solvents, were examined by scanning electron microscopy (SEM), Fourier transform infra-red (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing techniques. Morphological analyzes revealed better interfacial adhesion between the blend compo- nents in DMF than CHCl 3 . Almost no signs of miscibility were detected in PS/PSAN blends irrespective of the type of casting-solvent by FTIR probably due to very weak intermolecu- lar interactions. All the blend films, irrespective of the type of solvent, showed two glass transition temperatures that were composition-dependent in the case of PS + PSAN from DMF. However, in the case of PS/PSAN/chloroform blend system, almost all the blend compositions retained the T g values of their components. The T g results suggested partial miscibility of the components in the DMF and almost immiscibility in the CHCl 3 . Thermal degradation behavior also verified DSC results as PS/PSAN/DMF blend film having composition, 25/75 indicated greater thermal stability than the neat polymers, and other blend compositions. However, in the case of PS + PSAN from chloroform, all the blend compositions were thermally less stable as compared to the neat polymers. Mechanical properties also corroborated SEM, DSC, and TGA results for both the blend systems thereby confirming partial miscibility of PS + PSAN from DMF, and immiscibility of PS + PSAN from chloroform blend systems. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Polymer blending is an attractive method to obtain materials with tailored properties without manufacturing absolutely new polymers or copolymers [1–6]. The main purpose of blending is to attain synergism in the final properties of the resulting blend. The end properties of the resulting blend depend on the degree of miscibility between components, composition, solvent, and morphol- ogy of the blend. Many efforts have been made to under- stand miscibility of the blend components, in which the thermodynamic interaction between constituent polymers is of prime significance. Studies on the solvent cast blends are quite large but only limited number is dedicated to study the effect of casting solvent on properties of the resulting blends [7–12]. Keeping in view this, we decided to correlate our solution state studies [13] with the solid state investigations in order to examine the effect of casting solvents on the miscibility, morphology, thermal, and mechanical properties of the polystyrene (PS) and poly(styrene-co-acrylonitrile) (PSAN) blend films. The techniques used for this purpose include scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile tests. PS has been very successfully used in packaging, building, construction, and in injection moldings applications for http://dx.doi.org/10.1016/j.eurpolymj.2015.02.039 0014-3057/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Cell: +92 3339964813; fax: +92 966 9280134. E-mail address: zkmarwat2002@gmail.com (Z.K. Marwat). European Polymer Journal 66 (2015) 520–527 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj