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Dynamic mechanical properties of conductive carbon black-reinforced closed cell microcellular oil-extended EPDM rubber vulcanizates: Effect of blowing agent, temperature, frequency, and strain

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Abstract

Dynamic viscoelastic properties of Vulcan XC 72 (excess conductive carbon black)-reinforced solid- and closed-cell microcellular controlled long chain branching grade oil-extended EPDM (Keltan 7341A) rubber vulcanizates were studied at four frequencies of 3.5, 11, 35, and 110 Hz, and at a temperature range of −100 to 160°C.The effect of blowing agent (ADC 21) loading on storage modulus (E′) and loss tangent (tan δ) was studied. The log of storage modulus bears a linear relationship with the log of density for both solid and microcellular rubber. Relative storage modulus (Emath image/Emath image) decreases with decrease in relative density (ρfs). Both E′ and tan δ were found to be dependent on frequency and temperature. The master curves of the storage modulus versus log temperature-reduced frequency were formed by superimposing E′ results and by using shift factors calculated by Arrhenius equation. Strain-dependent isothermal dynamic viscoelastic properties were carried out for dynamic strain amplitude of 0.08–7%. Cole–Cole plots of microcellular vulcanizates show a circular arc with blowing agent (density). Empirical relationship between tan δ versus E′ is found to be linear, whose slope is independent of blowing agent loading or density. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1600–1608, 2006

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