Rheology, Morphology, and Crystallization Behavior of Melt-Mixed Blends of Polyamide6 and Acrylonitrile- Butadiene-Styrene: Influence of Reactive Compatibilizer Premixed with Multiwall Carbon Nanotubes Suryasarathi Bose, 1 Arup R. Bhattacharyya, 1 Pravin V. Kodgire, 2 Ashok Misra, 2 Petra Po ¨ tschke 3 1 Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India 2 Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India 3 Department of Polymer Reactions and Blends, Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany Received 20 April 2007; accepted 25 June 2007 DOI 10.1002/app.27018 Published online 21 August 2007 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Blends of polyamide6 (PA6) and acryloni- trile butadiene styrene (ABS) were prepared in presence or absence of up to 5 wt % of a reactive compatibilizer [sty- rene maleic anhydride copolymer (SMA) modified with 5 wt % multiwall carbon nanotubes (MWNT)] by melt- mixing using conical twin screw microcompounder where the ABS content was varied from 20 to 50 wt %. The melt viscosity of the blends was significantly enhanced in pres- ence of SMA modified by multiwall carbon nanotubes due to the reactive compatibilization, which leads to stabilized interphase in the blends. Furthermore, the presence of MWNT in the compatibilizer phase led to additional increase in viscosity and storage modulus. Morphological studies revealed the presence of either droplet-dispersed or cocontinuous type depending on the blend composi- tions. Further, reactive compatibilization led to a signifi- cant change in the morphology, namely a structure refin- ing, which was enhanced by MWNT presence as observed from SEM micrographs. DSC crystallization studies indi- cated a delayed crystallization response of PA6 in pres- ence of ABS presumably due to high melt viscosity of ABS. The crystallization temperature and the degree of crystallinity were strongly dependent on the type of mor- phology and content of reactive compatibilizer, whereas the presence of MWNT had an additional influence. SAXS studies revealed the formation of thinner and less perfect crystallites of PA6 phase in the blends, which showed cocontinuous morphology. A unique observation of multiple scattering maxima at higher q region has been found in the blends of cocontinuous morphology, which was observed to be successively broadened in presence of the compatibilizer. Ó 2007 Wiley Periodicals, Inc. J Appl Polym Sci 106: 3394–3408, 2007 Key words: compatibilization; crystallization; morphology; MWNT; PA6/ABS blends INTRODUCTION Blending of polymers is an important tool that often gives rise to the possibility of enhancing the overall properties of the material through a synergistic com- bination of desirable properties from each compo- nent. However, most polymer blends are immiscible because of their high molecular weight and unfavor- able interactions, thus forming multiphase struc- tures. Morphology is a key parameter next to the properties of component polymers in determining the properties of multiphase polymeric materials. 1,2 Two major types of morphology can be observed for melt blended immiscible polymers: the matrix dis- persed droplet structure and the cocontinuous struc- ture. In cocontinuous blends, both components form phases that partly or fully form a continuous phase. The thermodynamically unstable cocontinuous mor- phology is often observed for blends of a composi- tion near phase inversion. Such morphologies can be stabilized by the use of a compatibilizer, which resides at the polymer/polymer interface and reduces the interfacial tension between the blend components and prevents coalescence via steric sta- bilization. 3–7 However, the final morphology gener- ated during the melt processing of the blends crit- ically depends on the composition, viscosity, and elasticity ratio and interfacial tension between the components. It is believed that ‘‘emulsion effect’’ and ‘‘interlayer slip’’ are the two mechanisms oper- ating the melt viscosity in immiscible polymer blends. 8 It is also observed that the existence of Correspondence to: A. R. Bhattacharyya (arupranjan@iitb. ac.in). Contract grant sponsor: Department of Science and Tech- nology (DST), India (SERC Fast Track Scheme); contract grant number: 04DS047. Journal of Applied Polymer Science, Vol. 106, 3394–3408 (2007) V V C 2007 Wiley Periodicals, Inc.