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Effect of volume changes on segmental relaxation in siloxane polymers
M Paluch1, R Casalini, A Patkowski
1Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice, Poland.
Summary
Volume significantly impacts polymer relaxation dynamics, nearly matching thermal energy
Area of Science:
- Polymer science
- Materials science
- Physical chemistry
Background:
- Segmental relaxation times in polymers are crucial for understanding material properties.
- Temperature and pressure are known to influence these relaxation times.
- The interplay between volume and thermal energy requires further quantification.
Purpose of the Study:
- To quantify the relative contributions of volume and thermal energy to temperature-dependent segmental relaxation times.
- To investigate the role of volume in governing segmental dynamics in specific polymers.
- To explore a unified function for relaxation times based on volume.
Main Methods:
- Dielectric relaxation measurements were performed.
- Equation-of-state measurements were utilized.
- Polymethylphenylsiloxane and polymethyltolylsiloxane were the model polymers studied.
Main Results:
- Volume significantly contributes to the temperature dependence of segmental relaxation times, comparable to thermal energy.
- Relaxation times, under varying temperature and fixed pressure, correlate with normalized volume.
- Isothermal relaxation times at various pressures also follow a similar volume-dependent relationship.
Conclusions:
- Both volume and thermal energy are critical factors in polymer segmental dynamics.
- A volume-centric approach can unify the description of relaxation times across different conditions.
- This highlights the importance of free volume theory in polymer physics.