Analysis of Deformation Mechanism with Re-stretching of Stretched Polymer Film. Part II: Analyses of Deformation Band with Characteristic Curve and Re-orientation Behavior of Molecular Chain Axis with the Model of Plastic Slippage.

The characteristic curve and deformation band with yield points were investigated in off-axis angle stretching of strip-biaxially stretched poly (ethylene terephthalate) (PET) and isotactic polypropylene (it-PP) films. As the yield strain in polymers are much greater than those of metals, the change of orientation angles must be corrected for elastic-plastic deformation. The re-orientation mechanisms of chain axes during off-axis angle stretching may be divided into inter-lamella slippage and intra-lamella chain slip. The orientation of molecular chain axes by chain slip was much greater than that of inter-lamella slip.