Preparation and Properties of Thermoplastic Elastomer-Clay Nanocomposites from Unmodified and Chemically Modified Poly [styrene- (ethylene-cobutylene) – styrene] Triblock Copolymer
Unmodified and chemically modified poly [styrene-(ethylene-co-butylene)-styrene] (SEBS)- montmorillonite clay based nanocomposites have been prepared and characterized in the thesis. The investigations have focused on improving the physico-mechanical properties and structure-property relationship of SEBS-clay nanocomposites at very low concentration. The first part of the thesis emphasizes triblock SEBS copolymer based thermoplastic elastomer - clay nanocomposites in both solution cast and direct melt processes, employing unmodified hydrophilic (MT) and organically modified hydrophobic montmorillonite clays (OMT). Detailed microstructure by atomic force microscopy (AFM), transmission electron microscopy and X - ray diffraction alongwith physicomechanical, dynamic mechanical, thermal and optical properties for neat SEBS and its clay based nanocomposites have been determined. Comprehensive morphological characterization of the domain thickness, roughness, and quantification of hard-soft phases and localized forces in the particular domains by using of force-distance measurements by AFM has been attempted. The other part of the thesis delineates the effect of grafting of polar organic moieties (acrylic acid, maleic anhydride and sulphonic acid) onto SEBS backbone that generate different morphologies and enhance hydrophilic interaction with cheaper unmodified montmorillonite nanoclay. Synthesis, morphological investigation and analysis of dynamic mechanical and thermal properties, watermethanol mixture uptake and permeation, and AC resistivity have been carried out for sulphonated SEBS and their MT clay based nanocomposite. Finally, microstructures of all developed nanocomposites have been analyzed by using small angle X-ray scattering and modulated differential scanning calorimetry studies.