Publication: Structure-mechanical property correlations of model siloxane elastomers with controlled network topology
Issued Date
2009-01-16
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ISSN
00323861
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2-s2.0-58149288232
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Mahidol University
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SCOPUS
Bibliographic Citation
Polymer. Vol.50, No.2 (2009), 347-356
Suggested Citation
Kenji Urayama, Takanobu Kawamura, Shinzo Kohjiya Structure-mechanical property correlations of model siloxane elastomers with controlled network topology. Polymer. Vol.50, No.2 (2009), 347-356. doi:10.1016/j.polymer.2008.10.027 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/27440
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Title
Structure-mechanical property correlations of model siloxane elastomers with controlled network topology
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Abstract
We review our recent studies towards the molecular understanding of mechanical properties-structure relationships of elastomers using model polydimethylsiloxane (PDMS) networks with controlled topology. The model elastomers with controlled lengths of the network strands and known amounts of cross-links and dangling chains are obtained by end-linking the functionally terminated precursor PDMS with known molecular weights using multi-functional cross-linkers. Several modern entanglement theories of rubber elasticity are assessed in an unambiguous manner on the basis of the nonlinear stress-strain behavior of the model elastomers under general biaxial strains. The roles of cross-links and entanglements in the large-scale structure of the swollen state are revealed from small angle X-ray scattering spectra. A remarkably stretchable elastomer with the ultimate strain over 3000% is obtained by optimizing the network topology for high extensibility, i.e., by reducing the amounts of trapped entanglements and the end-to-end distance of the network strands. The model elastomers with unattached chains exhibit a pronounced viscoelastic relaxation originating from the relaxation by reptative motion of the guest chains. The relaxation spectra provide a definite basis to discuss the dynamics of guest linear chains trapped in fixed polymer networks. The temperature- and frequency-insensitive damping elastomers are made by introducing intentionally many dangling chains into the networks. © 2008 Elsevier Ltd. All rights reserved.