Download or read book Molecular Simulation Studies of Physical Aging and Rejuvenation in Polymer Glasses written by Yongchul G. Chung and published by . This book was released on 2013 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis provides the potential energy landscape description of mobility enhancement that follows deformation of polymer glasses. We show that there are two mechanisms which dictate the mobility enhancement {u2013} fold-catastrophe mechanism which reduces the barrier between the minima; and rejuvenation mechanism which moves the system to the regions of the energy landscape with lower barriers. We find both mechanisms are relevant during active deformation, but only rejuvenation mechanism is relevant mechanism after we stop deformation. We also show the structural characteristics of mechanically deformed glassy materials are different from the polymer glasses due to thermal rejuvenation. In the absence of temperature, the system dynamics show two linear regimes separated by a non-linear regime in response to different extent of shear, which correspond to different types of fold catastrophes {u2013} one that occurs between the local minima and one that occurs between the metabasins. Finally, we show that the aging dynamics in polymer glass are related to the transition between the metabasins, and these transitions occur less as the system evolves toward the low energy regions on the potential energy landscape with increasing barrier height between metabasins.