Tomoshige Naoya, Mizuno Hideyuki, Mori Tatsuya, Kim Kang, Matubayasi Nobuyuki
Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902, Japan.
Sci Rep. 2019 Dec 20;9(1):19514. doi: 10.1038/s41598-019-55564-2.
The excess low-frequency vibrational spectrum, called boson peak, and non-affine elastic response are the most important particularities of glasses. Herein, the vibrational and mechanical properties of polymeric glasses are examined by using coarse-grained molecular dynamics simulations, with particular attention to the effects of the bending rigidity of the polymer chains. As the rigidity increases, the system undergoes a glass transition at a higher temperature (under a constant pressure), which decreases the density of the glass phase. The elastic moduli, which are controlled by the decrease of the density and the increase of the rigidity, show a non-monotonic dependence on the rigidity of the polymer chain that arises from the non-affine component. Moreover, a clear boson peak is observed in the vibrational density of states, which depends on the macroscopic shear modulus G. In particular, the boson peak frequency ω is proportional to [Formula: see text]. These results provide a positive correlation between the boson peak, shear elasticity, and the glass transition temperature.
被称为玻色子峰的过剩低频振动光谱以及非仿射弹性响应是玻璃的最重要特性。在此，通过使用粗粒化分子动力学模拟来研究聚合物玻璃的振动和力学性能，特别关注聚合物链弯曲刚度的影响。随着刚度增加，系统在更高温度下（在恒定压力下）经历玻璃化转变，这降低了玻璃相的密度。由密度降低和刚度增加所控制的弹性模量对聚合物链刚度呈现出非单调依赖性，这种依赖性源于非仿射分量。此外，在振动态密度中观察到一个清晰的玻色子峰，它取决于宏观剪切模量G。特别地，玻色子峰频率ω与[公式：见原文]成正比。这些结果提供了玻色子峰、剪切弹性和玻璃化转变温度之间的正相关关系。
