Polymers exhibit viscoelastic behavior: their mechanical response depends on the loading time, or on the loading frequency. In addition, if a polymer structure has a long service life, the mechanical behavior can also depend on physical aging and chemical degradation. This paper describes a thermodynamically consistent constitutive law taking into account the viscoelastic phenomena and the physical aging. First, an original nonlinear viscoelastic law, depending on the physical aging time, is developed. Then, considering experimental values of dynamic modulus from the literature, the model parameters are identified, using a new method based on the discrete form of the spectrum of relaxation time. The obtained model is numerically implemented and compared to experimental results.

聚合物表现出粘弹性行为：它们的机械响应取决于加载时间或加载频率。另外，如果聚合物结构的使用寿命长，则机械行为也可能取决于物理老化和化学降解。本文介绍了考虑粘弹性现象和物理老化的热力学一致本构定律。首先，根据物理老化时间，开发了原始的非线性粘弹性定律。然后，考虑文献中的动态模量的实验值，使用基于松弛时间谱的离散形式的新方法，确定模型参数。对获得的模型进行数值实现，并与实验结果进行比较。