天然橡胶-铁界面力学性能的分子动力学模拟

Mechanical properties of natural rubber-iron interface based on molecular dynamics simulations

采用分子动力学方法,建立了天然橡胶-铁的界面模型,研究了聚合度、环境温度、拉伸速率对界面力学性能的影响。结果表明,界面力学性能与聚合度无关,但与温度、拉伸速率有密切联系,界面失效的主要原因是天然橡胶力学性能的衰减。随着温度的升高,分子链活动性增强,橡胶逐渐由“玻璃态”向“黏流态”转变,材料模量下降,界面分离所需的拉力也减小。当拉伸速率较大时,链段运动相对滞后,材料屈服需要更大的外力,因此界面拉力增大;当拉伸速率较小时,材料发生黏性流动,界面失效所需要的拉力减小。

The interface model of natural rubber-iron was established by molecular dynamics method,and the effects of degree of polymerization,environmental temperature and tensile rate on the mechanical properties of the interface were studied.The results show that the mechanical properties of the interface are not related to the degree of polymerization,but are closely related to the temperature and tensile rate.The main reason for the interface failure is the attenuation of the mechanical properties of natural rubber.As the temperature increases,the activity of molecular chains increases,the rubber gradually changes from‘glass state’to‘viscous flow state’,the elastic modulus decreases,and the tension required for interface separation decreases.When the tensile rate is large,the activity of molecular chains is relatively weak,and the material needs more external force to reach the yield state,so the interface tension increases.On the contrary,when the tensile rate is small,the viscous flow of rubber occurs,and the tension required for interface failure decreases.