Rheological and mechanical properties of PMMA/organoclay nanocomposites prepared via ultrasound-assisted in-situ emulsion polymerization

Abstract

This study investigated the rheological and mechanical properties of PMMA/organically modified Cloisite 30B nanocomposites (clay loading 1–5 wt%) synthesized via ultrasound-assisted in-situ emulsion polymerization. XRD patterns and TEM micrographs of the nanocomposites confirm complete exfoliation and uniform distribution of nanoclay platelets in host poly(methyl methacrylate) matrix. As a consequence, the nanocomposites synthesized with sonication were found to have superior properties as compared to the nanocomposites synthesized with mechanical stirring. Measurement of rheological properties using melt rheology revealed that magnitudes of storage modulus, loss modulus and complex viscosity increased with incorporation of clay platelets in polymer matrix due to the flow restriction of PMMA chains induced by nanofiller. Analysis of mechanical properties of nanocomposites showed maximum Young’s modulus of 1.8GPa with weight average molecular weight (Mw) of 581,130 g mol−1 for 2 wt% clay loading. The enhancements in rheological and mechanical properties of nanocomposites are attributed to the physical and chemical effect of ultrasound and cavitation, i.e. generation of intense microturbulence and free radicals in the emulsion polymerization reaction system.