Tensile strength is a measurement of the mechanical strength of the material and in the case of elastomers can be taken as a general indication of resistance to deterioration under stress, for example wear and cracking. However, there is no direct relationship between tensile strength and wear resistance. Other factors, such as roughness of the surface against which the seal rubs, and service temperature, can be more significant in practice.
The tensile strength of elastomers is generally low to moderate, polyurethane rubbers being the exception (see figure). Tensile strength also degenerates with increasing temperature. The actual value of tensile strength is not normally of critical importance in seals except those materials with a strength below 70 kg/cm2 may not be suitable for dynamic seals.