Peculiar Behavior of the Secondary Dielectric Relaxation in Propylene Glycol Oligomers near the Glass Transition

2008 ◽  
Author(s):  
K. Grzybowska ◽  
A. Grzybowski ◽  
M. Paluch ◽  
Michio Tokuyama ◽  
Irwin Oppenheim ◽  
...  
2001 ◽  
Vol 169 (1) ◽  
pp. 147-156
Author(s):  
Daniele Prevosto ◽  
Simone Capaccioli ◽  
Mauro Lucchesi ◽  
Pierangelo Rolla

2003 ◽  
Vol 41 (23) ◽  
pp. 3047-3052 ◽  
Author(s):  
C. M. Roland ◽  
T. Psurek ◽  
S. Pawlus ◽  
M. Paluch

Author(s):  
Martin G. Buehler

This paper describes the dielectric relaxation spectroscopy (DRS) method for obtaining glass transition temperature and the onset of crystallinity of skim milk powder (SMP). The methodology consists of exposing SMP samples to numerous constant temperatures, T, and water activities, aw, and measuring the relaxation time. Measurements are based on changes in the loss-tangent height at its peak frequency. Glass transition times are identified at peaks in the loss-tangent height versus time curve and the onset of crystallinity times are identified when the loss-tangent height collapses. The analysis leads to two boundary curves: glass transition Tg, aw curve and the onset of crystallinity Tc, aw curve. They separate the SMP stable (long shelf life) and unstable (short shelf life) regions. Two curve fitting algorithms were developed for (a) aw2, tg curve where tg is the time to glass transition and aw2, tc curve where time tc is the time to onset of crystallinity and (b) Tg, aw and Tc, aw boundary curves. Finally, the DRS data are compared to differential scanning calorimetry (DSC) results.


1951 ◽  
Vol 19 (12) ◽  
pp. 1484-1490 ◽  
Author(s):  
D. W. Davidson ◽  
R. H. Cole

1985 ◽  
Vol 18 (12) ◽  
pp. 2652-2663 ◽  
Author(s):  
S. Matsuoka ◽  
G. Williams ◽  
G. E. Johnson ◽  
E. W. Anderson ◽  
T. Furukawa

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