The characterization of poly(methyl methacrylate), (PMMA), by dielectric analysis and the study of the effects of beta-alkyl substitution on the dielectric properties

The mechanical and electrical properties exhibited by the polymethacrylates family of polymers in end-use applications are significantly influenced by the presence of relaxation transitions (alpha and beta transitions). Analyzing these transitions requires a technique that offers high sensitivity and good resolution. Dielectric analysis (DEA) can provide both of these required capabilities. Furthermore, DEA can accommodate the polymethacrylate in either film or powder form and can provide information continuously through the solid phase to well above the glass transition and into the fluid state. Dielectric analysis, which measures a material\´s response to an applied alternating voltage signal, provides an excellent means of characterizing thermoplastics. The actual properties monitored using dielectric analysis are e\´ (permittivity), which is a measure of the degree of alignment of the molecular dipoles to the applied electrical field; and e" (loss factor), which represents the energy required to align the dipoles or to move trace ions