Unique dynamic crossover in supercooled x,3-dihydroxypropyl acrylate (x = 1, 2) isomers mixture

Abstract

Abstract.: The previtreous dynamics in the glass-forming monomer, glycerol monoacrylate (GMA), was tested using the broadband dielectric spectroscopy (BDS). The measurements revealed a clear dynamic crossover at the temperature TB= 254 K and the time scale τ(TB) = 5. 4 ns for the primary (structural) relaxation time and no hallmarks for the crossover for the DC electric conductivity σDC. This result was revealed via the derivative-based and distortions-sensitive analysis d ln Ha/ d (1 / T) vs.1 / T , where Ha stands for the apparent activation energy. Subsequent tests of the fractional Debye-Stokes-Einsten relation σDC(τα)S=const showed that the crossover is associated with S= 1 (for T>TB)→S=0.84 (for T< TB. The crossover coexists with the emergence of the secondary beta relaxation, which smoothly develops deeply into the solid amorphous phase below the glass temperature Tg. Graphical abstract: [Figure not available: see fulltext.].