The glass transition temperature and rheological moduli of plasticized
corn gluten meal (CGM) were determined with dynamic mechanical therma
l analysis (DMTA). The tested plasticizers were water, glycerol, polye
thylene glycols (PEG) 300 and 600, glucose, urea, diethanolamine, and
triethanolamine, at concentrations of 10-30% (dwb). The glass transiti
on temperature (T-g) Of CGM, measured at 188 degrees C when unplastici
zed, was lowered by >100 degrees C at 30% plasticizer content, except
by PEG 600 and glucose, which showed limited compatibility with CGM pr
oteins. The highest plasticizing efficiency, on a molar basis, was mea
sured with PEG 300 and was attributed to the large number of hydrophil
ic groups and the high miscibility of this compound with CGM proteins.
The change in T-g due to the plasticizing effect was modeled with the
Gordon and Taylor equation, but a better fit of the experimental data
was obtained with the Kwei equation.