Morphology and thermal properties of Poly(methyl methacrylate)/silylated MMTs nanocomposites

Abstract

In this research, composites based on Poly(methyl methacrylate) (PMMA), and two kind of organomodified montmorillonites, Sodium clay (Dellite HPS) and organo-clay (Dellite 72T) sylilated by using chloro-dimethyl-octadecylsilane, are synthesized by in situ intercalative polymerization. Nanocomposites are filled with various amounts of MMTs (1%, 3%, and 5% wt). The influence of montmorillonite contents and type of organic modifier on clay dispersion and thermal properties of PMMA composites are investigated. The structural and morphological characteristics of nanocomposites are verified by XRD, SEM and TEM analyses and confirm that organomodification of Montmorillonite by organosilane is an efficient method to obtain an homogeneous dispersion of the clay in PMMA. Indeed XRD spectra indicate the formation of intercalated structure for silylated Del 72T and intercalated/exfoliated structure for organomodified Del HPS. SEM images of nanocomposites fractured surface show a good dispersion and distribution of montmorillonites in the polymer matrix. Finally TEM analysis of PMMA/silylated Del HPS nanocomposites shows MMT lamellae disorderly exfoliated in submicron domains homogeneously dispersed in PMMA. Nanocomposites glass transition temperatures are measured by differential scanning calorimetry and the thermal stability is measured by thermogravimetric analysis. They present an improvement of thermal properties respect to PMMA, the best result is obtained in presence of silylated Del HPS.