Anhydride/Epoxy Functionalized Blends: Mechanical, Rheological and Thermal Properties
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Anhydride/Epoxy Functionalized Blends: Mechanical, Rheological and Thermal Properties
Goknur Bayram and Ulku Yilmazer Middle East Technical University, Chemical Engineering Department, 06531, Ankara, TURKEY
ABSTRACT Blends of styrene-maleic anhydride (SMAH) and polyethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) were produced in a batch mixer and in a corotating twin screw extruder. E-MA-GMA concentration was varied from 0 % to 50 %. Batch mixing indicated that the blend system was reactive. Extruded blends were characterized in terms of rheological, thermal and mechanical properties, and their morphology was observed. Rheological properties such as the storage modulus, loss modulus and complex viscosity exhibited maxima at 25 % EMA-GMA content. The blends had fine morphology as observed by scanning electron microscopy. Thermal properties were not significantly affected by the change in epoxy concentration. As E-MA-GMA concentration increased, tensile strength and modulus of elasticity decreased, but percent strain at break increased. These observations could be explained in terms of the chain extension / branching reactions that occurred in mixing the blends. INTRODUCTION Reactive extrusion involves some common melt phase compatibilization reactions between functional groups such as epoxy, anhydride, alcohol, amine, isocyanate, oxazoline [1-3] and others. The polymer blends obtained by compatibilization with reactive groups have been analyzed by using different characterization techniques in order to understand the reaction characteristics of the systems [3-6]. Rheological, morphological, thermal and mechanical analyses are techniques, which are conventionally applied for the characterization of polymer blends. By measuring rheological properties such as storage modulus, G', loss modulus, G" and complex viscosity, η*, it is possible to get information on the effects of reactions on molecular weight, molecular weight distribution and chain branching [7, 8]. Morphological analysis is also important in order to confirm the reactions occurring in the system [9]. The objectives of this study are to produce compatibilized polymer blends in a batch mixer as well as a corotating extruder followed by characterization in terms of rheological, thermal, morphological and mechanical properties. In this way, it is expected to obtain information on the reaction characteristics of the functional groups selected for compatibilization. For this purpose, polyethylene/methyl acrylate/glycidyl methacrylate (E-MAGMA) and SMAH were chosen. EXPERIMENTAL SMAH (Dylark 232) was obtained from Nova Chemicals. The other material used in this study was the terpolymer of polyethylene-methyl acrylate-glycidyl methacrylate, E-MA-GMA U9.7.1
(Lotader AX8900) manufactured by Elf-Atochem. Hydrated zinc acetate, ZnAc.2H2O was used as a potential catalyst in the systems. The melt flow index values of SMAH and E-MA-GMA were reported as 1.9 and 6.5 g/10 min, respectively. GMA content of E-MA-GMA was reported as 7.25 % by weight. In addition t
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