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Quantifying changes in the low-frequency dynamics of amorphous polymers by 2D correlation mechanical spectroscopy
Xuebang Wu1, Huaguang Wang, Zhengang Zhu
1Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031, PR China. xbwu@issp.ac.cn
The Journal of Physical Chemistry. B
|December 14, 2012
Summary
Sub-Rouse modes in polystyrene exhibit dynamics similar to alpha relaxation, independent of molecular weight above a specific temperature. This suggests increased intermolecular cooperativity influences polymer glass transition.
Area of Science:
- Polymer Physics
- Materials Science
- Rheology
Background:
- Understanding polymer dynamics is crucial for material properties.
- Sub-Rouse modes represent a distinct relaxation mechanism in polymers.
- The role of molecular weight in sub-Rouse mode dynamics remains an area of investigation.
Purpose of the Study:
- To investigate the longer segmental dynamics of sub-Rouse modes in polystyrene.
- To determine the influence of molecular weight on these dynamics.
- To elucidate the relationship between sub-Rouse modes and the glass transition.
Main Methods:
- Utilized 2D correlation mechanical spectroscopy to analyze polystyrene.
- Separated sub-Rouse modes from alpha and Rouse relaxation processes.
- Examined dynamics across various molecular weights and temperatures.
Main Results:
- Sub-Rouse mode dynamics show a distinct change at T(B) ≈ 1.2T(g), mirroring alpha relaxation.
- At T(B), relaxation time is molecular weight-independent (≈0.1 s).
- Evidence suggests increased intermolecular cooperativity drives the observed dynamic changes.
Conclusions:
- Sub-Rouse modes exhibit properties akin to alpha relaxation.
- The dynamics are governed by the relaxation time scale and intermolecular cooperativity.
- Findings offer new insights into polymer glass transition mechanisms.
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