MODIFICATION OF THE MECHANISM OF DEFORMAT ION IN GLASSY THERMOPLASTS ON DRAWING IN ADSORPTION-ACTIVE MEDIA

The mechanism of orientational transition in thermoplasts changes from crazing to neck formation on drawing at a constant rate in an adsorpt ion-active medium. An analysis of this phenomenon shows that the chang e can be induced by inhomogeneous stress distribution at the stage of craze growth. Under certain conditions this inhomogeneity leads to the development of stress-strain field sufficient to deform polymer by th e mechanism of neck formation. A critical deformation rate, ensuring t he change in the mechanism of orientational transition, is calculated as a function of the thickness of film samples strained. The results o f the calculation agree satisfactorily with experimental data.