The Development and Testing of Elastomeric Materials for Fluid Sealing Applications

A Discussion Involving the Significance of Laboratory Test Methods and a Description of the Properties of Some of the Latest Polymers Including Rubbers Suitable for Use with Skydrol 500A Hydraulic Fluid. The significance of laboratory test methods now commonly applied to elastomeric materials is discussed in relation to service performance. Hardness, elastic recovery properties, heat resistance and liquid absorption are among the most important and experimental results are given to illustrate the effect of the various factors involved. Attention is drawn to the general properties of some of the newer polymers now becoming available. The development of rubbers for use with the fire‐resistant phosphate ester hydraulic fluid Skydrol 500A presented a problem because it is heavily absorbed by the usual oil‐resistant rubbers. First butyl rubber and subsequently ethylene/propylene copolymers were found suitable but the production of satisfactory materials for seals took time. Reference is made to other subjects of importance in the use of rubber for seals, such as the difference in the coefficient of thermal expansion of rubbers and metals, and the methods of reducing surface friction.