Epoxidized natural rubber for vibro-acoustic isolation

The performance of an elastomeric vibro-acoustic isolation system is governed by the dynamic properties of the material under service temperature and frequency conditions. This paper investigates the effect of epoxidation level on the dynamic properties of Epoxidized Natural Rubber (ENR). Dynamic properties of natural rubber with 0, 25 and 50 mol% epoxidation levels were measured in simple shear over a range of temperatures and frequencies and a master curve for their dynamic properties was generated based on the time-temperature superposition principle. These master curves and the Cole-Cole plot of their dynamic properties shows that the epoxidation level does not affect the relationship between the storage modulus and loss modulus, but merely shifts the master curves for natural rubber along the frequency axis. These observations would be of value for designing a vibration isolation system with an optimum level of epoxidation to achieve the desired storage modulus (or loss modulus) at the given service conditions. A reduced temperature nomogram is presented for the prediction of appropriate epoxidation level required for such design purposes. The 5-parameter fractional derivative model by Pritz [J. Sound & Vib., 265, 935–952 (2003)] was fitted to the master curves for the complex dynamic modulus of natural rubber with different epoxidation levels.