Dynamical mechanical analysis was carried out with a RSA2
spectrometer from Rheometrics, working in the tensile mode.
Samples were thin rectangular strips with dimensions about
25mm×7mm×1mm. The dynamic storage modulus (E) and loss
factor (tan ı) were measured as a function of temperature from
−100 to 100 ◦C, at a constant heating rate of 2 ◦C min−1, and at a frequency
of 1 Hz. The main relaxation temperature (T˛), associated
to the glass transition temperature of the samples, was determined
as the temperature at the maximum of the tan ı peak. The results
for the storage modulus (E) were normalized at low temperature