MEASUREMENT OF RUBBER ELASTICITY AT LOW TEMPERATURES USING A TWIST RECOVERY APPARATUS

摘要

Kinetic elasticity is an important and definitive property of rubber, yet it is difficult to measure at room temperature and even more difficult to measure at lower-than-room temperatures. Many current low-temperature test methods provide useful information about various properties of rubber but give little information about its elastic behavior or else measure elasticity under deformations greater than those likely to be found in service.nThe apparatus and methods described in this report provide a new means of observing and measuring the low-temperature behavior of rubber. Since, in actual use, rubber is very often deformed only slightly, the new method subjects the test specimen to a twist deformation of 360°, resulting in an elongation of approximately 5 percent along its side. The apparatus permits twist recovery and percentage of set to be measured at specific constant temperatures and also to be correlated with rising temperatures.nThe results show that, with the exception of a series of ethylene/ propylene/diene (EPD) rubber compounds, both the elasticity and the flexibility of rubbers are regained within the same range of low tempera-tures. The stress-strain behavior of EPD rubbers, which differs from that of other types of rubber, is briefly discussed.nThese techniques can be used not only to examine the basic behavior of rubbery materials, but also in the routine inspection of rubber items and components.