Rheology, morphology and mechanical properties of polyethylene/ethylene vinyl acetate copolymer (PE/EVA) blends M. Faker a,b,c , M.K. Razavi Aghjeh a, * , M. Ghaffari b,c , S.A. Seyyedi a a Institute of Polymeric Materials, Chemical Engineering Department, Sahand University of Technology, Sahand New Town, Tabriz, P.O. Box 51335-1996, Iran b Yazd Radiation Processing Center, P.O. Box 89175/389, Yazd, Iran c Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran, Iran article info Article history: Received 26 December 2007 Received in revised form 13 March 2008 Accepted 2 April 2008 Available online 15 April 2008 Keywords: Rheology Morphology PE/EVA blends Interfacial tension abstract Rheology, morphology and mechanical properties of binary PE and EVA blends together with their thermal behavior were studied. The results of rheological studies showed that, for given PE and EVA, the interfacial interaction in PE-rich blends is higher than EVA-rich blends, which in turn led to finer and well-distributed morphology in PE-rich blends. Using two different models, the phase inversion composition was predicted to be in 45 and 47 wt% of the PE phase. This was justified by morphological studies, where a clear co-con- tinuous morphology for 50/50 blend was observed. The tensile strength for PE-rich blends showed positive deviation from mixing rule, whereas the 50/50 blend and EVA-rich blends displayed negative deviation. These results were in a good agreement with the results of viscoelastic behavior of the blends. The elongation at break was found to follow the same trend as tensile strength except for 90/10 PE/EVA blend. The latter was explained in terms of the effect of higher co-crystallization in 90/10 composition, which increased the tensile strength and decreased the elongation at break in this composition. The results of thermal behavior of the blends indicated that the melting temperatures of PE and EVA decrease and increase, respectively, due to the dilution effect of EVA on PE and nucleation effect of PE on EVA. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction During the last few decades, increasing activities have been directed towards modification of existing polymers to produce new materials with desirable properties. Due to the possibility of attaining a wide range of properties through blending of two or more polymers, it has been known as one of the most applicable methods for modifica- tion of polymers [1,2]. There are a few couple of polymers, the mixing of which results in a miscible blend [3]. Mechanical properties of miscible blends obey linear mix- ing rules or show positive deviation from mixing rules. Be- cause of the small combinatorial entropy and positive enthalpy of mixing, most of the polymer blends are immis- cible and therefore they display multiphase morphology [4]. Mechanical properties of such blends can strongly be affected by the phase morphology and interface properties [5]. Moreover, the morphology is influenced by the ther- modynamical and rheological parameters and also process conditions. Therefore, the mechanical behavior of immisci- ble blends becomes more complicated. It has clearly been understood that rheological parameters such as viscosity and elasticity ratio of the blend components have a remarkable influence on the phase structure of the blends [2,3]. On the other hand, the rheological behavior of the blends is dependent on the type of morphology as well as interfacial interaction between phases [6]. So, the infor- mation obtained from the rheological studies can be used in the prediction of morphology and therefore mechanical properties of the blends. 0014-3057/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2008.04.002 * Corresponding author. Tel.: +98 4123459085; fax: +98 4123444355. E-mail address: karimrazavi@sut.ac.ir (M.K. Razavi Aghjeh). European Polymer Journal 44 (2008) 1834–1842 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj