SUMMARY

The mechanical and physical properties of polymers are determined primarily by the underlying nano-scale structures such as entanglements, crystallites, and molecular orientation. These structures evolve in complex manners during the processing of polymers into useful articles. Limitations of available and foreseeable computational capabilities prevent the direct determination of macroscopic properties directly from atomistic computations. As a result, computational tools and methods to bridge the length and time scale gaps between atomistic and continuum models are required. In this research, an internal state variable continuum model has been developed whose state variables and evolution equations are related to the nano-scale structures. Separate atomistic models and methods have been developed to investigate the nano-scale structures that affect mechanical behavior: particularly the evolution of entanglements during thermo-mechanical deformations. The results of these simulations are used to gain a clearer understanding of the mechanisms involved to enhance the physical basis of the evolution equations in the continuum model and to derive the model’s material parameters. The end result is a continuum model that reflects the atomistic structure of the polymer.