Relaxation Studies in PEO/PMMA Blends

Abstract

To study the influence of PEO on the relaxation process of PMMA, the real and imaginary parts of the permittivity, ε‘ and ε‘ ‘, of PEO/PMMA blends (with PEO contents up to 25 wt %) were measured as a function of frequency and temperature, and the results obtained were compared with those of pure PMMA. It is shown that the presence of PEO broadens the relaxation process of PMMA and increases its relaxation strength. The lower Tg component (PEO) has a plasticizing effect on the relaxation of PMMA, for the blends with 10 and 15% PEO. The splitting of the αβ process of PMMA seems to be affected by the presence of the second component, being the onset of the α relaxation shifted to lower temperatures with the increase of PEO concentration. The DSC thermograms show a single glass transition temperature, which is displaced to lower temperatures with the increase of PEO content, and no evidence of crystallinity was found. The presence of a singular broad transition in the 20% PEO blend, evidenced in both dielectric and calorimetric experiments, may be associated with the merging of the α and β process and to concentration fluctuations, confirming that this blend lies in the border of the miscibility/immiscibility region.