Looking for the simplicity in polymer networks - Structure changes and comparative analysis of theoretical approaches to deformation of semi-crystalline polymers

To establish relationships between the molecular structure of polyolefines and their physical characteristics which determine possible commercial applications, structural changes and tensile deformation response up to deformations beyond the natural draw ratio were investigated using a variety of experimental approaches. True stress-strain curves were measured at different temperatures so as to estimate the available effective network density, which will eventually define the failure mode of the material under investigation. Analysis of the deformation by means of tensile strain hardening, assuming the Haward-Thackray spring dashpot decoupling assumption by means of Edward-Vilgis' non-Gaussian rubber-elastic slip-link model, reveals the role of transient and fixed network nodes. It was established by differential scanning calorimetry and X-ray diffraction analysis that the transformation from lamellar to fibrillar morphology passes through the several pronounced stages: deformation of initial lamellae (lambda