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The strain-dependent dynamic storage modulus of a poly(dimethyl-siloxane-co-methylvinyl-siloxane-co-methylphenyl-siloxane)-based silicone elastomer (PVMQ), which is reinforced with fumed silica and crosslinked with peroxide, is investigated. The time dependence of the dynamic storage modulus on the magnitude of the mean strain at a particular test condition is investigated. The dynamic modulus results are shown to depend on the time of cycling as well as the relative magnitudes of the dynamic and mean strains. The relaxation of the force required to maintain the mean strain is observed to depend on the magnitude of the dynamic strains and the data are shown to be consistent with static stress relaxation experiments in the limit of zero dynamic strain. Recovery of the dynamic modulus from the exposure to higher strain cycling is seen to be facilitated by dynamic cycling with higher cycling strains yielding faster recovery rates. The observed phenomena are interpreted in terms of the role of entanglements in the polymer phase on the dynamic behavior of the elastomer material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2197–2204, 2007

The strain-dependent dynamic storage modulus of a poly(dimethyl-siloxane-co-methylvinyl-siloxane-co-methylphenyl-siloxane) based silicone elastomer, which is reinforced with fumed silica and crosslinked with peroxide, is investigated. The dependence of the resulting dynamic storage modulus on the duration of cycling at a particular test condition is investigated and compared to static stress relaxation measurements in the same strain range. The dynamic modulus results are shown to depend on the time of cycling at the current test conditions as well as the time of cycling at prior conditions of lower strains. The relaxation is shown to be related to the time of cycling rather than the number of cycles performed. The pattern of behavior of the relaxation of the dynamic modulus with respect to peak strain amplitude is different than that observed in a static stress relaxation test, both of which show significant nonlinear effects in strain. The observed phenomena are interpreted in terms of the role of the polymer phase on the dynamic behavior of the elastomer material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1001–1009, 2005

The effect of peroxide crosslinking on the dynamic modulus of a silica-reinforced silicone [poly(dimethylsiloxane)] elastomer was investigated. Three different peroxides (t-butyl peroxide, t-butyl perbenzoate, and benzoyl peroxide) were employed at various practical loadings and differences in the nonlinear behavior of the dynamic modulus were found. Results are discussed with respect to changes in crosslinking density and the identity of the peroxide. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1504–1512, 2005