3.1 Synthetic plasticizers are primarily esters and they are used with the more polar elastomers such as CR or NBR to improve processing, adjust hardness, and improve low temperature properties. These esters may be either monomeric or polymeric and are derived from many different organic acids.

3.2 These test methods may be used in establishing and confirming quality control standards for the synthetic plasticizers used in rubber compounding. It is not implied that the test methods in this guide are the only ones of significance, but these test methods list the properties most commonly specified for ester plasticizers. Other parameters may be needed for specific application of these materials.