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Static and dynamic properties of model elastomer with various cross-linking densities: a molecular dynamics study
Jun Liu1, Dapeng Cao, Liqun Zhang
1Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China.
The Journal of Chemical Physics
|July 24, 2009
Summary
Increasing polymer cross-linking density slightly raises the glass transition temperature and hinders chain mobility and relaxation. Higher cross-linking leads to broader relaxation and increased fragility in polymer networks.
Area of Science:
- Polymer Physics
- Materials Science
- Computational Chemistry
Background:
- Understanding polymer network properties is crucial for material design.
- Cross-linking density significantly influences polymer network behavior.
Purpose of the Study:
- To investigate the impact of cross-linking density on static and dynamic properties of polymer networks.
- To explore the molecular mechanisms behind residual stress in elastomers.
Main Methods:
- Molecular dynamics simulations using a simple elastomer model.
- Analysis of static structure factor, glass transition temperature (Tg).
- Examination of monomer/chain diffusion, dynamic structure factor, and end-to-end vector correlation.
Main Results:
- Cross-linking density has minimal effect on static structure factor but slightly increases Tg.
- Monomer and chain mobilities are reduced, and relaxation is hindered with increased cross-linking.
- Time-temperature superposition holds at segmental but not chain length scales.
Conclusions:
- Cross-linking density affects polymer network dynamics, leading to broader relaxation and increased fragility.
- Molecular insights into residual stress in elastomers are provided, linked to deformation and relaxation processes.
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