Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Structural Properties and Local Chain Dynamics of Polymeric Materials Using Molecular Dynamics" By L. Lorena Alzate Vargas Purdue MSE Ph.D. Final Exam Advisor: Professor Alejandro Strachan ABSTRACT The use of atomistic level simulations like molecular dynamics are becoming a key part in the process of materials discovery, optimization and development since they can provide complete description of a material and contribute to understand the response of materials under certain conditions or to elucidate the mechanisms involved in the materials behavior. We will discuss to cases in which molecular dynamics simulations are used to characterize and understand the behavior of materials: i) prediction of properties of small organic crystals in order to be implemented in a multiscale modeling framework which objective is to predict mechanically induced amorphization without experimental input other than the molecular structure and ii) characterization of temperature dependent spatio-temporal domains of high mobility torsions in several bulk polymers, thin slab and isolated chains; strikingly we observe universality in the percolation of these domains across the glass transition. However, as in any model, validation of the predicted results against appropriate experiments is a critical stage, especially if the predicted results are to be used in decision making. Various sources of uncertainties alter both modeling and experimental results and therefore the validation process. We will present molecular dynamics simulations to assess uncertainties associated with the prediction of several important properties of thermoplastic polymers; in which we independently quantify how the predictions are affected by several sources. Interestingly, we find that all sources of uncertainties studied influence predictions, but their relative importance depends on the specific quantity of interest. Date: Monday, November 25, 2019 Time: 11:00 A.M. Place: HAMP 2117