Mechanical and optical characterization of a photoviscoplastic material

The mechanical and optical properties of a polyester blend over a wide range of strain rates has been investigated for loading and unloading. The mechanical behavior, while being complex, was modeled adequately with a generalization of the four-parameter viscoelastic model. The optical behavior has at least a three-phenomenological coefficient dependence on the mechanical variables. Further, the stress birefringence is of opposite sign to that of the deformation.