PHOTOVISCO-ELASTOPLASTIC BEHAVIOR OF POLYCARBONATE MATERIAL UNDER CREEP AND TENSION TESTS

Polymers are widely used as photomechanical models of a prototype mate rial (often a metal). Photoplasticity is one of the methods used in or der to show the behavior of plastic materials stressed beyond the line ar elastic limit. To illustrate this process we have analyzed the phot ovisco-elastoplastic behavior of polycarbonate as a photoplastic mater ial. In this paper a technique for local and simultaneous measurement of birefringence and principal strains is presented. The mechanical an d optical properties, at room temperature, have been evaluated by mean s of uniaxial tension tests. A series of creep tests has been carried out in order to study the photovisco-elastoplastic behavior of polycar bonate. In two different experiments we analyzed nonlinear birefringen ce and the amplitude of the corresponding strains. We could thus evalu ate the distribution of strains and the distribution of uniaxial stres s for each birefringence state and vice versa.