3-D STRUCTURE-PROPERTY RELATIONSHIPS IN ROLLTRUDED POLYMERS .2. ANISOTROPIC YIELDING AND DEFORMATION IN TRIAXIALLY ORIENTED POLYMERS

Rolltrusion, a single step solid state deformation process, has been successfully applied to isotactic poly(propylene), iPP, to produce unique 3‐D properties. Mechanical property enhancement not only occurs in the principal draw direction, but also in the transverse directions. A systematic series of standard (ASTM) tensile and compressive experiments were made on well oriented materials supporting this claim. Tensile testing was also performed on dumb‐bell shaped specimens cut at various angles to the main deformation direction. A variety of observations were made during testing. Deformation bands, anisotropic yielding, and ductile‐to‐brittle behavior were observed. These results are presented along with a morphological model that has been developed to account for the behavior of these unique triaxially oriented polymers. Copyright © 1990 Society of Plastics Engineers