Analysis Technique for Determining the Levels of Organic Additives in an EPDM Rubber for Use in Underwater Acoustic Applications.

Ethylene-propylene diener monomer EPDM rubber is being considered for applications in underwater electroacoustic transducers. This material is attractive for such applications because it is acoustically transparent over a wide range of frequencies with very low loss and has an excellent environmental resistance. An optimized Navy EPDM formulation for transducer applications has been developed at Underwater Sound Reference Detachment USRD under the support of the Office of Naval Research ONR Acoustic Transduction and Metrology Program. In order to ensure that the Navy receives materials as specified according to this EPDM formulation, analytical procedures for determining the various ingredients in EPDM rubber need to be developed for quality-control purposes. An analytical procedure for determining the organic additive levels in this EPDM formulation is given in this report. By using a liquid-solid chromatography LSC method, one can now measure reproducibly the percentages of dicumyl peroxide DCP, trimethylolpropane trimethacrylate TMPTMA, and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline TMDQ in EPDM rubber. Chemical structures for these materials are shown. This procedure was tested by conducting a blind study on three compounded EPDM rubbers and was proven to be satisfactory.