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Published on: June 30, 2018
Pattern formation in thin polystyrene films induced by an enhanced mobility in ambient air
A Serghei1, H Huth, M Schellenberger
1Institute for Experimental Physics I, University of Leipzig, 04013 Leipzig, Germany.
Summary
Polystyrene films form patterns in air above their glass-transition temperature due to oxygen-induced chain scission, lowering the glass-transition temperature and increasing relaxation rates.
Area of Science:
- Materials Science
- Polymer Physics
- Chemical Engineering
Background:
- Polystyrene films exhibit unique pattern formation when subjected to specific environmental conditions.
- Understanding the factors influencing polymer film behavior above the glass-transition temperature is crucial for material stability and application.
Purpose of the Study:
- To investigate the mechanism behind the characteristic pattern formation in polystyrene films in ambient air.
- To elucidate the role of environmental factors, specifically oxygen, in altering polystyrene film properties.
Main Methods:
- Broadband dielectric spectroscopy
- Capacitive dilatometry
- AC calorimetry
- Infrared spectroscopy
Main Results:
- Pattern formation was observed exclusively in ambient air, not in vacuum or nitrogen.
- Oxygen exposure led to a decrease in the glass-transition temperature and an increase in the average relaxation rate.
- Infrared spectroscopy confirmed oxygen-induced chain scission, shifting the molecular weight distribution to lower values.
Conclusions:
- Oxygen-induced chain scission is the primary driver for pattern formation in polystyrene films above their glass-transition temperature.
- The observed changes in dynamic glass transition kinetics are a direct consequence of molecular weight reduction.
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