Dispersion of Functionalized Nanoclay Platelets in an Amine-Cured Epoxy Resin System
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Dispersion of Functionalized Nanoclay Platelets in an Amine-Cured Epoxy Resin System D. Raghavan, E. Feresenbet, D. Yebassa, A. Emekalam, and G. Holmes1 Polymer Division, Department of Chemistry, Howard University, Washington DC 20059. 1 G. Holmes, Polymer Division, National Institute of Standards & Technology, Gaitherburg, MD 20899. ABSTRACT Nanocomposites are a relatively new class of materials obtained by dispersing montmorillonite clay in a polymer matrix. Evidences from literature suggest that clay platelet dispersion during nanocomposite preparation and clay-matrix adhesion are major technical issues that need to be addressed in order to achieve the desired property enhancements in polymer-clay hybrid nanocomposites. We have studied the interaction of the organically functionalized clay with the epoxy resin by including along the chain structure functional groups that will facilitate interaction with the resin. Through conventional routes, functional molecules have been synthesized and deposited on to the clay surface. Both the functionalized and nonfunctionalized clay has been analyzed using thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The exfoliation of nanoclay platelets in amine cured epoxy system has been studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). INTRODUCTION Aromatic amine cured epoxy resins, where the diglycidyl ether of bisphenol-A (DGEBA) resin cured with meta-phenylene diamine (MPDA) is a representative member, are the most widely used matrix materials for preparing conventional composites. Resins of this class are brittle and their ability to absorb energy during failure is limited. The successful use of nanoclay reinforcement technology to improve the performance of epoxy resin would represent a major technical achievement in the development of hightemperature and tough advanced structural materials. Nanoclays are inexpensive relative to traditional reinforcing materials, thermally inert, and environmentally friendly. The use of nanoclay hybrid polymer composites in structural parts is expected to improve environmental and moisture stability and increase energy efficiency in the transportation sector through weight reduction [1]. Evidences from literature suggest that exfoliation and dispersion of clay platelets during nanocomposite preparation and clay-matrix adhesion are major issues that needs to be addressed in order to achieve the desired property enhancements in polymer-clay nanocomposites [2-7]. In recent years, efforts have focussed on understanding the nature and mechanism of the exfoliation process of the surface treated clay in the polymer network structure. For example, Messersmith and Giannelis [2] achieved a significant increase in stiffness of epoxy nanocomposite by using organoclays modified with bis(2hydroxyethyl) methyl tallow-alkyl ammonium chloride at a mass fraction of 4 %. The V9.26.1
role of the organic chain on alkyl ammonium chloride is primarily to facilitate the intercalation of the clay
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