双分散聚合物玻璃中的应变硬化：分离链取向和链缠结的作用。

Strain hardening in bidisperse polymer glasses: separating the roles of chain orientation and interchain entanglement.

机构信息

Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA.

出版信息

J Chem Phys. 2009 Dec 28;131(24):244901. doi: 10.1063/1.3276800.

PMID:20059109

Abstract

The effects of entanglement and chain orientation on strain hardening in glassy polymers are separated by examining mixtures of chains with different lengths. Simulations show that the orientation of a molecule of a given chain length is the same in monodisperse systems and bidisperse mixtures, even when entangled and unentangled chains are mixed. In addition, the stress in mixtures is equal to the weighted average of the stresses in monodisperse systems. These results indicate that chains contribute independently to strain hardening, that chain orientation is determined by local interactions with the surrounding glass, and that entanglements play at most an indirect role in strain hardening in the range of strains typically studied. We discuss these results in the context of recent theories.

摘要

通过考察具有不同长度的链的混合物，将纠缠和链取向对玻璃态聚合物的应变硬化的影响分离开来。模拟表明，即使混合了缠结和未缠结的链，给定链长的分子在单分散体系和双分散混合物中的取向是相同的。此外，混合物中的应力等于单分散体系中应力的加权平均值。这些结果表明，链独立地对应变硬化作出贡献，链取向由与周围玻璃的局部相互作用决定，并且缠结在通常研究的应变范围内对应变硬化最多起间接作用。我们在最近的理论背景下讨论了这些结果。