Correlation between Compression-Set and Compression Stress-Relaxation of Epichlorohydrin Elastomers

Set behaviour has always been regarded as an efficient and experimentally facile way of assessing sealing performance. However, many argue that stress-relaxation, which is a little more complicated to assess compared to set, should be the principal property by which sealing behaviour should be ranked. Given the experimental ease with which set can be determined, it is therefore desirable to develop a relationship combining stress-relaxation with the simplicity of compression-set so as to circumvent the need for determining the experimentally arduous property of compression stress-relaxation. Such a relationship will clearly couple experimental convenience with a reliable parameter for assessing sealing behaviour. Thus, the object of the present paper is to investigate the extent to which compression-set results can be used to indicate stress-relaxation behaviour. In this endeavour a mathematical model proposed by Ellul and Southern ¹ is employed. The overall conclusion is similar to that of other workers who have carried out work of this nature, but notably, it was found that the model was sufficient for ranking purposes.