Modulus continued resilience

The total resilient modulus is calculated using total recoverable deformation, which includes both the instantaneous recoverable and the time-dependent continuing recoverable deformation during the rest period portion of one cycle. 

Inside the shell is a core of a more resilient, energy-absorbing polymer such as crosslinked polybutadiene, natural rubber, butadiene-styrene copolymer or butyl acrylate. The rubbery phase is thus prevented from mixing with the continuous phase (the polymer being toughened) and lowering its modulus. 

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