Dielectric spectroscopy study of EMA–EGDM crosslinking system at sol–gel transition

Investigation of the sol–gel transition of electrochemically prepared acrylamide bisacrylamide gels

“…A maximum in dielectric constant, consistent with the gel point, was observed during the gelation of bulk polymers, and at the same point the dielectric loss switched from a linear decrease to a relatively constant behavior [21]. The radical concentration for bulk polymers, i.e.…”

“…One is the value of the voltage applied between working and reference electrodes, second is the number (or the concentration) of the charge carriers, and third is the mobility of the charge carriers. The radicals, although neutral, are highly electrophylic and act as charge carriers [21]. In general two populations of radicals may exist.…”

“…After 1940s, the scientists involved both in the areas of Chemistry and Physics have extensively studied the formation and physical properties of gels (like swelling and volume phase transition), thus several experimental techniques have been employed to study the gelation processes for many different polymeric systems. These include rheological measurements [11][12][13][14], dynamic light scattering [6,15], volume measurements [16,17], fluorescence measurements [18][19][20], and dielectric measurements [21,22].…”

“…Recently, some investigations on the kinetics of the polymerization were made by means of dielectric measurements [21,22] and electron spin resonance [23]. A maximum in dielectric constant, consistent with the gel point, was observed during the gelation of bulk polymers, and at the same point the dielectric loss switched from a linear decrease to a relatively constant behavior [21].…”

Evidence of pre-crystalline-order in super-cooled polymer melts revealed from simultaneous dielectric spectroscopy and SAXS

“…The increasing permittivity can be explained by an additional dipole moment, as e.g. discussed for a cross-linking system [47], or by the formation of additional internal surfaces, which results in a Maxwell-Wagner-Sillars process. These additional dipole moments or interfaces must be created before crystallinity can be detected by SAXS or DSC.…”