A detailed study of the influence of organic modifier structure (alkyl chain length C8-C20, single vs ditallow) and thereby, the effect of hydrophobicity on the structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)–clay hybrids, is presented. PMMA hybrids were prepared by melt processing and characterized using wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Intercalated PMMA nanocomposites were formed with organoclays containing organic modifier having at least twelve CH<sub>2</sub> groups. The degree of intercalation is found to increase with increase in the clay content and alkyl chain length of the organic modifier. The glass transition temperature (T<sub>g</sub>) for nanocomposites increased by ~ 4 °C at 2 wt% organoclay. The Vaia-Giannelis mean-field lattice model was used to predict the free energy for nanocomposite formation, which showed reasonable match with the experimental results and provides a general guideline for proper selection of polymer and organoclay to obtain nanocomposite. Tensile modulus for nanocomposites was higher than composites and increased with alkyl chain length of organic modifier and clay loading, with maximum improvement of 58 % observed.  The level of improvement in tensile properties obtained from primary and secondary ammonium modified clay is same as that obtained with commercially available organoclays.

Critical organic hydrophobic modifier aliphatic tail-length for formation of poly(methyl methacrylate) (PMMA)-montmorillonite nanocomposites

2019 Fall National Meeting

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