Elastomers viscoelastic rupture

Viscoelastic Rupture of Elastomers Failure in highly stretched elastomers is by no means instantaneous (27-29). A common home example... 

The attention of the author has been drawn to an interesting study by Bartenew (Piaste u. Kautschuk, 17, 235 (1970)1 in which the correlation of viscoelastic behaviour and rupture properties is attempted. This deals only with gum elastomers, but when it will be extended to reinforced vulcanizates, it may throw additional light on the subject of this review... 

Stress relaxation experiments involve the measurement of the force required to maintain the deformation produced initially by an applied stress as a function of time. Stress relaxation tests are not performed as often as creep tests because many investigators believe they are less readily understood. The latter point is debatable, and it may only be that the practical aspects of creep measurements are simpler. As will be shown later, all the mechanical parameters are in theory interchangeable, and so all such measurements will contribute to the understanding of viscoelastic theory. Whereas stress relaxation measurements are useful in a general study of polymeric behavior, they are particularly useful in the evaluation of antioxidants in polymers, especially elastomers, because measurements on such systems are relatively easy to perform and are sensitive to bond rupture in the network. 

This envelope may be used to describe relaxation, creep or constant strain rate measurements. A change in strain rate or temperature only shifts a point along the failure envelope, which is thus dependent only on the structural characteristics of the elastomer. The ultimate properties of rubbers are mainly governed by their viscoelastic properties, and reduced master curves can be obtained for tensile strength and strain as a function of time to break. The failure process is a non-equilibrium one, developing with time and involving the consecutive rupture of the molecular chains. The ultimate properties can then be predicted from creep measurements. ... 

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