Molecular Simulation Studies of Physical Aging and Rejuvenation in Polymer Glasses

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 – 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 – 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.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemical Engineering

Grantor dc:publisher

Case Western Reserve University School of Graduate Studies

Year dc:date

2013

Author dc:creator

• Chung, Yongchul G.

Contributors dc:contributor

• Lacks, Daniel J.

• Chemical Engineering
• molecular simulation
• physical aging
• polymer glass
• deformation

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=case1353512130

OAI identifier oai:identifier

oai:etd.ohiolink.edu:case1353512130