The β dielectric relaxation in some methacrylate polymers

Abstract

Dielectric results at frequencies between 6 × 10−4 and 105 Hz are given for the β relaxation region of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), poly(butyl methacrylate) (PBMA), and poly(isobutyl methacrylate) (PisoBMA). Apparent activation energies and relaxation strengths are calculated, as well as the relaxation time distribution and the form factor of the Fuoss‐Kirkwood equation. It is found that in PMMA, PEMA, and PBMA, the activation energy of the β relaxation is the same, the maxima occurring at the same frequency for the same temperatures, in accordance with the dynamic mechanical results of Heijboer, the dielectric results of Mikhailov, and at variance with data of Tetsutani et al. It is also found that the form factor follows the same temperature dependence. Data on the β relaxation of poly(hydroxyethyl methacrylate) (PHEMA), not previously reported, are also presented, and the displacement toward high temperatures of the β relaxation of PisoBMA and PHEMA is justified.

Relationship between the dielectric and mechanical properties and the ratio of epoxy resin to hardener of the hybrid thermosetting polymers

“…[19][20][21][22][23][24][25][26] Dieletric relaxation technique allows to study changes in ionic and dipolar mobilities of a thermoset material when it is subjected to an alternating electric field. [27][28][29][30][31][32][33][34][35][36][37] In dielectric analysis, the capacitance and conductance of a material can be measured as a function of time, temperature, and frequency. This allows the determination of electrical polarization and conduction of the material.…”

DEA and DSC study of cubic silsesquioxane epoxy resin nanocomposites

“…Dielectric relaxation technique allows studying changes in ionic and dipolar mobilities of a polymeric material when it is subjected to an alternating electric field [29][30][31][32][33][34][35][36].…”

Tacticity effects on the barriers to rotation of the ester methyl group in poly (methyl methacrylate): A deuteron magnetic resonance study

“…11,12 Unlike 1 H NMR which is dominated by dipolar interactions and sensitive to intermolecular interactions, the quadrupolar interactions responsible for 2 H NMR are dominated by single particle interactions and the results are directly comparable to the incoherent neutron scattering results. We report in this paper a study of the selectively deuterated material PMMA-D 3 . In this case, however, it is the deuterated ester group which is studied, and therefore it is important to note the effect of the doubling of the atomic mass on the spectra.…”

“…The higher frequency motions of the two methyl groups ͑␦ relaxation for the ester CH 3 and ␥ for the ␣͒ are conveniently studied by neutron quasielastic and inelastic scattering. The ester relaxation in particular has been the subject of a series of studies from several groups.…”

“…As the temperature nears T g these segments begin to move and eventually, well above T g , allow the translational motion associated with the liquid state. [2][3][4] Polymer molecules with side groups may have a number of other relaxation processes in the glassy state, associated with the reorientation of these side groups. Poly͑methyl methacrylate͒ ͑PMMA͒ ͑see Fig.…”