Dynamics of poly(methyl methacrylate)–montmorillonite nanocomposites: A dielectric study

Abstract

The effect of varying amounts of montmorillonite (MMT) filler (in weight ratios of 100/0, 100/5, and 100/10) on the molecular dynamics and polarization of atactic poly(methyl methacrylate) (PMMA) is investigated using broad-band dielectric spectroscopy from 10 −2 to 10 6 Hz and at temperatures from 30 to 140 °C. The experimental data were analyzed with the sum of Havriliak-Negami (HN) functions and a power-law conduction term. The characteristic frequency, activation energies, and dielectric strength of PMMA/MMT nanocomposites were analyzed. As MMT content increases, a Maxwell-Wagner-Sillars (MWS) relaxation emerges in the nanocomposites and the α-relaxation contributed by main-chain movements above T g occurs at lower temperatures as silicate layers in MMT segregate PMMA chains into smaller domains. The characteristic frequency of β-relaxations is influenced by the mergence with the α-relaxation above T g. Further, the strength of the β-relaxation is stable as a function of temperature in both pure PMMA and the PMMA/MMT nanocomposites whereas, in the nanocomposites, the strengths of the αand MWS relaxations increase significantly with temperature up to approximately 120 °C.

Thermal properties and electric modulus approach to the analysis of dielectric relaxation of nanocomposites based on carbon dots

“…Examination of these figures yield the following initial observations: ε ″ and M ″ decrease with increasing frequency and the relaxation peak is not observed at low temperatures. Such behavior is in contrast with what happens at high temperature, for which ε ″ and M ″ exhibit a narrow relaxation peak above 1 kHz which can be ascribed to the β relaxation …”

Fabrication of poly(methyl methacrylate)/silica KIT-6 nanocomposites via in situ polymerization approach and their application for removal of Cu2+ from aqueous solution

“…Because of these properties, PMMA has been widely used in the medicine, optical and supercapacitor, automobile, hydrogen storage material and construction industries. [21][22][23][24][25][26] However, PMMA has some drawbacks including a brittle texture, low thermal and mechanical stability and insufficient surface hardness. It has been reported that the addition of mesoporous materials, such as mesoporous carbon or silica, to the polymer matrix like PMMA results in an increase in the performance of the polymer and its thermal and mechanical behavior.…”

Superior optical and dielectric properties of ultrasonic-assisted solution-cast prepared PMMA/MMT nanocomposite films

“…Figure 5 presents the variation of ε ′ , ε ′′ , and tanδ with frequency f for the pure PMMA film and the PMMA/MMT films at fixed temperature of 30 • C. The pure PMMA film exhibited a small decrease in its ε ′ value that is from 2.2 to 1.97 with the increase of electric field frequency from 20 Hz to 1 MHz, whereas its ε ′′ value lies in the range 0.046-0.014, and tanδ value in the range ∼0.021-0.007. This range of ε ′ and significantly low ε ′′ and tanδ values confirm the PMMA film as promising low dielectric material for its use as insulator and dielectric substrate in fabricating numerous electronic devices [7,8,17,29,39].…”