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Abstract
Some Effects of Anaerobic Ageing, Stress Softening and
Recovery on the Modulus and Damping of Certain NR Vulcanisates for Anti-seismic
Bearings
Data are shown which
quantifies and helps to predict some effects of anaerobic and repeated shear deformations
on the modulus and damping properties of selected high damping NR vulcanisates.
For such vulcanisates the results show that at a given ageing temperature the
increase in modulus associated with anaerobic ageing can be reasonably
accurately predicted when plotted as a function of the square root of the
ageing time. Measurements showing the influence of different test strains and
the number of cyclic deformations at a constant stain on the modulus and
damping properties of these vulcanisates are also given. Some cumulative
effects of anaerobic ageing, stress softening and recovery on the modulus and
damping properties during certain applied strain histories relevant to
anti-seismic bearings are also shown. Such results indicate that stress softening
can have the dominant effect on the modulus of a vulcanisate at small strains
whereas at larger strains anaerobic ageing can be the dominant factor.

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