Relaxation studies in PEO/PMMA blends

To study the influence of PEO on the relaxation process of PMMA, the real a nd imaginary parts of the permittivity, epsilon' and epsilon", of PEO/PMMA blends (with PEO contents up to 25 wt %) were measured as a function of fre quency and temperature, and the results obtained were compared with those o f pure PMMA. It is shown that the presence of PEO broadens the relaxation p rocess of PMMA and increases its relaxation strength. The lower T-g compone nt (PEO) has a plasticizing effect on the relaxation of PMMA, for the blend s with 10 and 15% PEG. The splitting of the alpha beta process of PMMA seem s to be affected by the presence of the second component, being the onset o f the alpha relaxation shifted to lower temperatures with the increase of P EO concentration. The DSC thermograms show a single glass transition temper ature, which is displaced to lower temperatures with the increase of PEO co ntent, and no evidence of crystallinity was found. The presence of a singul ar broad transition in the 20% PEO blend, evidenced in both dielectric and calorimetric experiments, may be associated with the merging of the alpha a nd beta process and to concentration fluctuations, confirming that this ble nd lies in the bolder of the miscibility/immiscibility region.