ON THE DETERMINATION OF THE ZERO MODULUS OF RUBBER

An algorithm for the determination of the modulus at true zero strain of a rubber vulcanizate ("zero modulus") has been developed based on a relationship proposed by Yeoh, by means of a regression of recorded digitalized values. The calculated values of the zero modulus eliminate the effect of initial tension or slack almost invariably obtained during tensile testing. Correlations obtained indicate that at the same hardness, the zero modulus is different for compounds containing carbon black or other fillers, and depends upon the curing system or other compounding variations.