Ak. Rizos et al., A dielectric relaxation study of the gamma-relaxation in tetramethylbisphenol A polycarbonate plasticized by tris(2-ethylhexyl) phosphate, MACROMOLEC, 32(23), 1999, pp. 7921-7924
Dielectric relaxation spectroscopy (DR) was employed to study the dynamics
of glassy tetramethylbisphenol A polycarbonate (TMBPA-PC) containing variou
s amounts of tris(2-ethylhexyl) phosphate (TOP) added as diluent molecules.
The present data confirm that the gamma-relaxation dynamics, at constant f
requency, shift to lower temperatures with increasing TOP content, an effec
t observed for the first time by dynamic mechanical measurements. This beha
vior of the gamma-relaxation in TMBPA-PC plasticized by TOP is to be contra
sted with that in bisphenol A polycarbonate (BPA-PC) plasticized by TOP. In
the latter case, the gamma-relaxation dynamics, at constant frequency, shi
ft to higher temperatures with addition of TOP. These opposite trends of th
e gamma-relaxation dynamics in two similar polycarbonates are surprising. H
owever, the results can be rationalized by the coupling model.