Mechanisms of the Improved Stiffness of Flexible Polymers under Impact Loading

The flexible polymers have an outstanding impact-resistant performance because of the improved stiffness upon a high speed loading. At the aspect of microstructure, the soft segments make an important contribution. In this article, molecular dynamics simulation is carried out to reveal the dynamic mechanical behavior of a mono helical soft segment. The tensile loadings at various strain rates are conducted. The stress–strain relations and strain rate dependencies of mechanical properties are derived. The evolution of potential energy with straining accompanied by the disentanglement of molecular chain is characterized. The characteristic molecular chain of dynamic mechanical response is determined. The intrinsic physical origins of straightening of characteristic molecular chain and bond angle expansion are explored. New parameters are defined to quantitatively analyze the micro mechanisms and their rate dependencies, which are linked to the dynamic mechanical properties. This work is full of interest to fill a knowledge gap of the physical origins of dynamic mechanical behavior of flexible polymers.