Page 216 - Handbook of Plastics Technologies

ELASTOMERS

4.8 CHAPTER 4

FIGURE 4.7 “Spring-and-dashpot” model for viscoelastic behavior.

FIGURE 4.8 Dynamic storage modulus and tan δ as a function of temperature for a typical un-
cross-linked elastomer.

and very sluggish and lossy (hysteretic) with a rather leathery consistency. With further
heating, the material becomes rubbery.
As stated above, a major difference between an elastomer and a glassy polymer is the
value of T . Thus, T is a major characteristic of a polymeric material, determining
g
g
whether it is glassy or rubbery at its temperature of use.
4.2.2 The Presence of Cross-Links in Elastomers
The cross-links of a vulcanized elastomer anchor elastomer molecular segment chain-ends
together at cross-link junctures such that many molecular monomer units span the distance

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