Liquid-to-liquid relaxation of polystyrene melts investigated by low-frequency anelastic spectroscopy.

Polystyrene melts with a narrow distribution of molecular weights far above the glass transition have been investigated by use of low-frequency anelastic spectroscopy. A liquid-to-liquid relaxation occurs when the molecular weight (M) is either above or below the critical molecular weight (M) for chain entanglement. As the molecular weight increases, the relaxation temperature (T) increases and the movement of the polymer chain is easier for short chains than for long chains.