Chemistry Reference
In-Depth Information
7.5 ORIENTATION
When an elastomer is deformed, its network chains become oriented. Ori-
entation is of both fundamental and practical importance.
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96,
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For
example, since orientation decreases the entropy of the network chains,
the melting points of the elastomer can increase significantly, which can
induce crystallization. This strain-induced crystallization improves the
mechanical properties of the elastomer.
In the case of polysiloxane elastomers, segmental orientation has been
of interest for both elongation
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393
and compression.
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7.6 SOME VISCOELASTIC RESULTS
Examples of early studies in this area include studies of PDMS liquids,
395
PDMS solutions (e.g., in toluene),
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and PDMS elastomeric networks.
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REFERENCES
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Means of Mechanical Property Measurements. In
Synthesis, Characterization,
and Theory of Polymeric Networks and Gels
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