title: Liquid-to-liquid relaxation of polystyrene melts investigated by low-frequency anelastic spectroscopy.
abstract: 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 (Mn) is either above or below the critical molecular weight (Mc) for chain entanglement. As the molecular weight increases, the relaxation temperature (Tp) increases and the movement of the polymer chain is easier for short chains than for long chains. In the range we investigated (Mn∼1.0 × 104-2.1 × 105), the relaxation time (τp) corresponding to the dissipation peak is related to the molecular weight by [Formula: see text]. This is consistent with theoretical prediction. We suggest that the dissociation of the chain clustering is responsible for the liquid-to-liquid relaxation.
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Science, PO Box 1129, Hefei 230031, People's Republic of China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Shang
authors.forename: Zhenguang
authors.initials: Z
authors.lastname: Zhu
authors.forename: Zaijun
authors.initials: Z
authors.lastname: Lu
authors.forename: Guangzhao
authors.initials: G
authors.lastname: Zhang