Specific Features of Strain Dependences of Loss Modulus in Highly Stretched Elastomers

The loss modulus E ″ in elastomer strips stretched by a factor of λ is studied theoretically. A small oscillating deformation is applied to these strips in the transition frequency zone between the glassy and rubbery states. The range of λ under study ranges up to ultimate extensions close to fracture. A model of E ″/ λ dependence in the transition frequency zone is suggested that considers the possible distortion in the local chain structure in the ultimate extension range. It is found that E ″ in the range of moderate and high λ increases owing to the finite extensibility of the chains. However, upon further extension up to ultimate values, E ″ decreases and a maximum appears on the E ″/ λ curves. These features are also confirmed experimentally.