ABS/clay nanocomposites obtained by a solution technique: Inﬂuence of clay organic modiﬁers M. Modesti a, * , S. Besco a , A. Lorenzetti a , V. Causin b , C. Marega b , J.W. Gilman c , D.M. Fox d , P.C. Trulove e , H.C. De Long f , M. Zammarano c a Department of Chemical Process Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy b Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy c Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA d Department of Chemistry, American University, Washington, DC 20016-8014, USA e Chemistry Department, US Naval Academy 572M Holloway Road, Annapolis, MD 21402-5026, USA f Directorate of Chemistry and Life Sciences, Air Force Ofﬁce of Scientiﬁc Research, Arlington, VA 22203-1768, USA Received 10 December 2006; received in revised form 16 January 2007; accepted 20 January 2007 Available online 15 August 2007 Abstract Acrylonitrile-butadiene-styrene (ABS) polymer/clay nanocomposites were produced using an intercalationeadsorption technique from poly- mer in solution: polymer/clay suspensions were subjected to ultrasonic processing to increase the effectiveness of mixing. Several kinds of or- ganically modiﬁed layered silicates (OMLS) were used to understand the inﬂuence of the surfactant nature on the intercalationeexfoliation mechanism. We show that only imidazolium-treated montmorillonite (DMHDIM-MMT) is stable at the processing temperature of 200  C, used for hot-pressing, whereas alkyl-ammonium modiﬁed clays show signiﬁcant degradation. The morphology of ABS based polymer nanocomposites prepared in this work was characterized by means of wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dynamic-mechanical analysis (DMA) was used to determine the storage modulus and damping coefﬁcient as a function of temperature, and to investigate the correlations between mechanical properties and morphology of the nano- composites. The thermal stability was assessed by means of thermogravimetric analysis (TGA). DMA and TGA show that the nanocomposites based on imidazolium-modiﬁed clay out-perform the nanocomposites based on quaternary-ammonium-modiﬁed clays in terms of mechanical properties and thermal stability. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: ABS; Nanocomposites; Solution; Organic modiﬁers 1. Introduction The addition of small fractions of a nanometric ﬁller to a polymer matrix has a large potential to improve the polymer properties. Smectite-type clays with a layered structure, such as montmorillonite (MMT) are commonly employed nanomet- ric ﬁllers. MMT has a layered structure in which each layer is 1 nm thickness and has lateral dimensions ranging from 30 nm to several microns [1]. The performance of polymereclay nanocomposites strongly depends on clayepolymer interac- tions, which can be improved through dispersion and exfolia- tion of the clay [2,3]. Three typologies of composites can be deﬁned depending on the degree of ﬁllerematrix interactions: conventional composite, intercalated nanocomposite and exfo- liated nanocomposite. In a conventional composite the clay sheets remain stacked in micrometric structures called tactoids with no increase in the layer-to-layer distance (d-spacing) as compared to the pristine clay; in an intercalated nanocompo- site polymer chains penetrate into the interlayer region and increase the d-spacing; a further increase in d-spacing gives * Corresponding author. Tel.: þ39 049 8275541; fax: þ39 049 8275555. E-mail address: michele.modesti@unipd.it (M. Modesti). 0141-3910/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2007.01.036 Available online at www.sciencedirect.com Polymer Degradation and Stability 92 (2007) 2206e2213 www.elsevier.com/locate/polydegstab