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

摘要

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 α relaxation and the α' (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_α' and the relaxation strength Δ_α' decrease, while T_α decreases and Δ_α increases. Moreover, the fractional free volume sharply increases above T_α' for all the samples, due to the bigger value of thermal expansion coefficient α_f.