Page 217 - Handbook of Plastics Technologies

ELASTOMERS

ELASTOMERS 4.9

FIGURE 4.9 Dynamic storage modulus and tan δ as a function of
angular frequency for a typical uncross-linked elastomer.

TABLE 4.1 Glass Transition and
Melting Temperatures of Selected
Plastics and Vulcanized Elastomers

T , °C T , °C
m
g
Elastomers
Butadiene rubber – –102
Natural rubber – –60
Neoprene rubber – –43
Butyl rubber – –73
Silicone rubber – –127
Poly(butyl acrylate) – –55
Styrene-butadiene rubber – –52
Plastics

Polyethylene 135 –78
Polypropylene 165 –13
Poly(vinyl chloride) – 81
Poly(ethylene terephthalate) 280 69
Nylon 6 260 40
Polystyrene – 100

between cross-links. The resistance to deformation is somewhat increased by the presence
of cross-links, and T changes only slightly. However, the presence of the cross-links
g
causes a rubber specimen to spring back to its original shape when the deforming stress is
removed. If the deformed elastomer specimen snaps back to nearly its original shape rap-
idly with respect to the time scale of the experiment, it is said to be resilient. Resilience is
the percentage of energy returned per cycle of rapid deformation upon removal of the

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