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Stability of polymer glasses vitrified under stress
Laura A G Gray1, Connie B Roth
1Department of Physics, Emory University, Atlanta, GA 30322, USA. cbroth@emory.edu.
Soft Matter
|March 22, 2014
Summary
Applying stress during the formation of polymer glasses makes them less stable. Stressed polymer glasses exhibit faster physical aging, indicating a trapped, higher-energy state even after stress removal.
Area of Science:
- Materials Science
- Polymer Physics
- Glass Transition Phenomena
Background:
- Understanding how stress influences the mobility and stability of glassy materials is a key scientific challenge.
- This research connects concepts of jamming and the glass transition across diverse material types, including polymers.
Purpose of the Study:
- To investigate the impact of applied stress during vitrification on the subsequent stability of the glassy state.
- To determine if stress applied during cooling affects polymer glass properties after stress removal.
Main Methods:
- Utilized entangled polymers, mechanically manipulated above their glass transition temperature.
- Applied stress during rapid cooling (vitrification) of polymer films.
- Measured the physical aging rate of the resulting polymer glasses.
Main Results:
- Polymer glasses formed under stress during vitrification showed reduced stability and increased physical aging rates.
- A stress threshold was observed, below which aging rates remained constant, and above which they increased rapidly.
- These effects persisted even after the removal of applied stress.
Conclusions:
- Stress applied during polymer vitrification can trap the system in a less stable, higher energy state.
- This leads to an accelerated physical aging rate in the resulting polymer glasses.
- The findings highlight the critical role of processing conditions in determining the long-term properties of glassy materials.
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