Melt linear viscoelastic rheological analysis to assess the microstructure of polyamide 6–acrylonitrile butadiene styrene terpolymer immiscible blends via the application of fractional Zener and Coran models Mahboobeh Aminjafari, 1 Mehdi Entezam, 2 Morteza Sadeghi, 1 Mahmood Masoumi, 1 Hossein Ali Khonakdar , 3,4 Seyed Hassan Jafari 5 1 Chemical Engineering Department, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan, Iran 2 Department of Chemical and Polymer Engineering, Faculty of Engineering, Yazd University, Yazd 89195-741, Iran 3 Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran, Iran 4 Leibniz Institute of Polymer Research Dresden, D-01067, Dresden, Germany 5 School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran Correspondence to: M. Entezam (E - mail: m.entezam@yazd.ac.ir) ABSTRACT: In this study, the melt linear viscoelastic rheological properties of polyamide 6 (PA6)–acrylonitrile butadiene styrene ter- polymer (ABS) immiscible blends were analyzed with the help of Coran and fractional Zener models (FZMs) to assess the micro- structure of the blends. For this purpose, dynamic shear flow experiments and scanning electron microscopy investigations were performed. The nonzero value of the elastic modulus of the spring element (G e ) of the FZM for ABS-rich blends was explained by the formation of a networklike structure because of the agglomeration of the rubber phases of the ABS matrix, whereas for the PA6- rich blends with a high content of ABS, the interactions and/or interconnectivity of the ABS dispersed phase led to a nonzero value of G e . The value of the fitting parameter of the Coran model (f ) was near to 0.5 for the 50/50 blend; this was fully in agreement with the formed cocontinuous morphology for this blend composition. On the other hand, the f value for the blends with a matrix– droplet-type morphology was near to zero for the PA6-rich blends; this indicated the lower continuity of the ABS dispersed phase as a harder phase compared to the PA6 soft matrix, whereas the f value was near to 1 for ABS-rich blends. This confirmed the forma- tion of an interconnected networklike structure for this series of blends. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45423. KEYWORDS: morphology; rheology; viscosity and viscoelasticity Received 21 February 2017; accepted 9 June 2017 DOI: 10.1002/app.45423 INTRODUCTION As is well known, the blending of the polymers is one of the most efficient ways to obtain new materials with desired beneficial prop- erties. 1,2 From thermodynamic point of view, the mixture of a cou- ple of polymers mostly results in an immiscible polymer blend with a multiphase morphology. 3 The performance of such polymer blends is intensively influenced by the phase morphology and inter- facial properties. 4 The morphological development during mixing and the interfacial properties are governed by thermodynamic and rheological parameters and also the processing conditions. In this case, the rheological properties of the polymer blend components play a key role. On the other hand, the rheological behavior of the blends themselves is dependent on the microstructure and the inter- facial properties of the blend. 5 On this basis, the investigation of the rheological behavior of immiscible polymer blends along with that of their polymer components has been taken into consideration as a crucial technique for probing the microstructure and even the inter- facial properties of these blends. 1,6–12 Polyamide 6 (PA6)–acrylonitrile butadiene styrene terpolymer (ABS) immiscible blends are the polymer systems of high com- mercial and scientific interest because of high their performance for applications where supertough materials with a high thermal stability, good chemical resistance, and excellent dimensional stability are required. The main application areas of these blends are automotive interior components, power tools, garden equip- ment, sporting goods, medical equipment, and furniture. 13,14 A considerable number of research works have been published on different aspects of compatibilized PA6–ABS blends, 13–22 but there has been little work on the relationship between the rheol- ogy and morphology of these blends without compatibilizer. V C 2017 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2017, DOI: 10.1002/APP.45423 45423 (1 of 9)