Rubber Home > Physical and Chemical
Properties > Ozone and Oxidation Resistance
Oxidation, which quickly destroys organic elastomers, is virtually
nonexistent with Silastic® silicone rubber.
Silastic silicone rubber, when tested for resistance to ozone, shows
excellent stability. After both static and dynamic testing for periods of two,
four, six, and eight hours, samples had no significant change in durometer
hardness, tensile strength, or elongation. Under a magnification of 10, no
cracking or checking was visible.
The tests followed procedures of ASTM D518 and ASTM D1149 with some modifications to match the outstanding properties of
Silastic silicone elastomers. As specified in ASTM D518, specimens were
stretched 20 percent. However, in addition to this static condition, a dynamic
test elongated specimens 25 percent in a cycle of 30 stretches per minute. This
cycling, if the rubber were affected by ozone, would result in the rapid
propagation of any cracking. As stated, no cracking or checking occurred.
Other test modifications concern test method ASTM D1149. Under this
procedure, a concentration of 50 parts of ozone per 100 million parts of air is
specified. And, for Silastic silicone rubber, this was increased to a
concentration of 30,000 parts of ozone. The procedure also states that a
temperature of 40 or 50°C may be used. Silastic silicone rubber tested
successfully at 74°C.
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