To ensure success in design of elastomeric parts for use at low temperature, the design engineer must understand the peculiar properties of rubber materials at these temperatures. There are no static applications of rubber. The Gaussian theory of rubber elasticity demonstrates that the elastic characteristic of rubber is due to approximately 15% internal energy and the balance, 85%, is entropy change. In other words, when an elastomer is deformed, the elastomer chain network is forced to rearrange its configuration thereby storing energy through entropy change. Thermodynamically, this means that rubber elasticity is time and temperature dependent (Reference 25). The purpose of this report is to provide guidance on low temperature properties of rubber with the terminology, test methods, and mathematical models applicable to rubber, and to present some practical experience.
This specification covers a chloroprene (CR) rubber in the form of sheet, strip, tubing, and molded shapes. These products have been used typically for parts requiring resistance to weather, such as window channels, bumper pads, chafing strips, and seals, for use from -40 to +100 degrees C (-40 to +212 degrees F), but usage is not limited to such applications.