Micro-mechanical analysis of the confined amorphous phase in semi-crystalline polymers.

Abstract: The mechanical modelling of semi-crystalline polymers is highly complex due to their different micro-structural scales and to some lacks regarding the understanding of the respective contributions of crystalline and amorphous phases on the macroscopic behaviour. In particular, the important role of the confined amorphous phase has to be investigated. To this aim, this work proposes to combine full-field simulations with kinematics field measurements at the same scale. The material is the linear low density polyethylene (LLDPE), chosen for its “simple” microstructure. Displacement fields at the micro-scale are measured by using the digital image correlation technique in the SEM. It is scheduled to apply the experimental strain as periodic boundary conditions to a unit cell whose morphological content will be built from the observed real microstructure and to analyse both the resulting macroscopic average response and local fields. To this aim, specific numerical tools are developed notably for statistical field analysis. The results on a simple stack model under various loading cases/paths are presented as a preliminary stage before the complete analysis for the LLDPE under tensile tests. The long term aim is to better understand the strain mechanisms in the confined amorphous phase, to determine its mechanical behaviour and conclude on its influence on the macroscopic behaviour. [Copyright &y& Elsevier]