Specific interaction characteristics in organoclay nanocomposite of miscible poly(styrene-co-acrylonitrile) and poly(vin
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We propose a new method for the preparation of the polymer/organoclay nanocomposite, termed the solution and melt mixing (SOAM) method, where the polymer and clays are first blended in solution, and subsequently the mixture is further blended in the melt. We prepared the ternary nanocomposite systems of poly(styrene-co-acrylonitrile) (SAN), poly(vinyl chloride) (PVC) and Cloisite25A clays (C25A) by solution blending as well as by the SOAM method. The C25A content in the nanocomposite was optimized by analyzing the x-ray diffraction (XRD) data of binary mixtures (SAN/C25A and PVC/C25A nanocomposites). The values of the interaction parameter (ab) were calculated by using the molar attraction constants of the specific functional groups derived from Hoy’s table. While PVC and C25A were shown to be highly compatible, SAN and C25A were less compatible. XRD data and transmission electron microscopy observations indicated that the SAN/PVC/C25A nanocomposites had at least partially exfoliated structures. The tensile modulus and the elongation at break of the nanocomposites prepared by the SOAM method were higher than those prepared by simple solution blending. I. INTRODUCTION
Polymer/layered silicate nanocomposites have attracted great interest over the past decade because of their improved physical properties when compared with pristine polymer or conventional micro- and macrocomposites. It has been shown that only a few percent of layered silicates dispersed in the polymer matrix could lead to a significant enhancement in various properties.1–7 Although many polymers have been used to prepare nanocomposites with layered silicates, only a handful of work has been carried out on nanocomposites based on polymer blend systems. Voulgaris and Petridis showed that the organoclays could act as emulsifiers in the PS/ poly(ethyl methacrylate) blend.8 Gelfer et al. showed that the domain size of the polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend was drastically reduced with the addition of clay, and claimed that it was due to the combination of partial compatibilization by excessive surfactant in the organoclays and increased local viscosity in the interfacial region.9 Wang and coworkers reported that the decreased domain size in the PS/ polypropylene (PP) blend by the addition of clays could
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2008.0148 1168 J. Mater. Res., Vol. 23, No. 4, Apr 2008 http://journals.cambridge.org Downloaded: 13 Mar 2015
be attributed to the fact that two immiscible polymer chains could reside together between the intercalated clay platelets, thereby playing the role of block (or graft) copolymers.10 Kamal et al. showed that the addition of 5 wt% clay to the high-density polyethylene (PE)/Nylon6 blend reduced the size of the dispersed Nylon 6 domains, and the dispersed domain changed from the spherical shape to the lamellar shape.11 Previously, we reported the preparation and interaction characteristics of organoclay with a miscible polymer blend of pol
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