Studies of Particle Dispersion in Poly(methyl methacrylate)/Organically Modified Montmorillonite Nanocomposites

ABSTRACT

Poly(methyl methacrylate) (PMMA) was mixed with 1, 3, 5, 7, and 10 wt% of Cloisite 15A to obtain PMMA-based nanocomposites. The thermal stabilities of the obtained nanocomposites were characterized by thermal analysis using a thermogravimetric analyzer (TGA), which showed that addition of organoclay to PMMA up to 5 wt% increased its thermal stability, whereas thermal stabilization was less efficient at 10 wt%. The interaction between PMMA and silicate layers was studied by Fourier transform infrared (FTIR) spectroscopy, which confirmed strong interactions between the nanometric silicate layers and PMMA segments. The electrical properties were studied through the permittivity, dielectric loss, and conductivity measurements. The electrical conductivity, which describes the ionic mobility of the systems, was studied as a function of temperature and showed that the conductivity of PMMA was enhanced upon increasing the organoclay content up to 5 wt% and was then decreased to some extent with a further increase to 10 wt%. The activation energy, E _σ, obtained from the dependency of electrical conductivity (σ) on temperature using the Arrhenius equation, was found to be lowest for the composite containing 5 wt% of organoclay. The dispersed behavior of organoclay in the PMMA matrix was identified using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, and it was found that the organoclay layers were homogeneously dispersed in the PMMA matrix when 5 wt% of Cloisite 15A was used.

KEYWORDS:

• poly(methyl methacrylate)
• organoclay
• nanocomposite
• montmorillonite
• electrical properties
• exfoliation