Theory of Aging, Rejuvenation, and the Nonequilibrium Steady State in Deformed Polymer Glasses

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Physical Review E

DOI:https://doi.org/10.1103/PhysRevE.82.041804· OSTI ID:1009934

Chen, Kang ^[1]

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1. Soochow University, Suzhou, People's Republic of China

The nonlinear Langevin equation theory of segmental relaxation, elasticity, and mechanical response of polymer glasses is extended to describe the coupled effects of physical aging, mechanical rejuvenation, and thermal history. The key structural variable is the amplitude of density fluctuations, and segmental dynamics proceeds via stress-modified activated barrier hopping on a dynamic free-energy profile. Mechanically generated disorder rejuvenation is quantified by a dissipative work argument and increases the amplitude of density fluctuations, thereby speeding up relaxation beyond that induced by the landscape tilting mechanism. The theory makes testable predictions for the time evolution and nonequilibrium steady state of the alpha relaxation time, density fluctuation amplitude, elastic modulus, and other properties. Model calculations reveal a rich dependence of these quantities on preaging time, applied stress, and temperature that reflects the highly nonlinear competition between physical aging and mechanical disordering. Thermal history is erased in the long-time limit, although the nonequilibrium steady state is not the literal fully rejuvenated freshly quenched glass. The present work provides the conceptual foundation for a quantitative treatment of the nonlinear mechanical response of polymer glasses under a variety of deformation protocols.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1009934
• Journal Information: Physical Review E, Journal Name: Physical Review E Journal Issue: 4 Vol. 82; ISSN 1539-3755
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AGING
AMPLITUDES
DEFORMATION
ELASTICITY
FLUCTUATIONS
FREE ENERGY
GLASS
LANGEVIN EQUATION
POLYMERS
RELAXATION
RELAXATION TIME
aging
polymer
rejuvenation