Effects of polyethylene oxide on the dynamics of the α and α′ relaxations observed in polystyrene by low-frequency anelastic spectroscopy

The relaxation dynamics in amorphous polystyrene and blends with polyethylene oxide (PEO) has been investigated by low-frequency anelastic spectroscopy. The dissipation spectra exhibit two relaxation peaks, corresponding to the alpha relaxation and the alpha(') (liquid-liquid) transition, respectively. The origin of the liquid-liquid transition is the inhomogeneity in the melt due to the chain clustering. With increasing PEO content, the peak temperature T-alpha' and the relaxation strength Delta(alpha') decrease, while T-alpha' decreases and Delta(alpha) increases. Moreover, the fractional free volume sharply increases above T-alpha' for all the samples, due to the bigger value of thermal expansion coefficient alpha(f). (c) 2007 American Institute of Physics.