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Updated: May 8, 2026
09:32
Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Enthalpy relaxation and annealing effect in polystyrene
Waki Sakatsuji1, Takashi Konishi, Yoshihisa Miyamoto
1Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan. sakatsuji.waki.87s@st.kyoto-u.ac.jp
Summary
Thermal history significantly impacts enthalpy relaxation in polystyrene. Annealing below the glass transition temperature causes entropy decay and physical aging, affecting specific heat behavior.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Understanding thermal history effects is crucial for predicting polymer behavior.
- Enthalpy relaxation and physical aging are key phenomena in glassy polymers.
- Polystyrene serves as a model system for studying these effects.
Purpose of the Study:
- To investigate the influence of thermal history on enthalpy relaxation in polystyrene.
- To quantify the temperature dependence of specific heat and relaxation times.
- To apply a phenomenological model to understand entropy evolution and memory effects.
Main Methods:
- Differential scanning calorimetry (DSC) was employed.
- Sinusoidal temperature variation was used to measure thermal response.
- A phenomenological model was applied to analyze enthalpy relaxation and entropy evolution.
Main Results:
- The study determined the temperature dependence of specific heat in liquid and glassy states.
- Relaxation time and the Kohlrausch-Williams-Watts exponent were quantified.
- Annealing below the glass transition temperature induced entropy decay and increased relaxation time due to physical aging.
Conclusions:
- Thermal history profoundly influences enthalpy relaxation in polystyrene.
- The interplay between entropy decay and physical aging dictates the observed behavior.
- The findings provide insights into the memory effects and aging processes in polymers.
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