From crystalline block slips to dominance of network stretching - Mechanisms of tensile deformation in semi-crystalline polymers

Abstract

The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curves obtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and the amorphous phases. However, the relative weights of the two portions change with the deformation stage. At low deformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows the system to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the force generated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformation mechanism then changes into a disaggregation - recrystallization process.