Characterization of PLA/Palm fiber films by conventional tensile test and digital image correlation

Abstract

Accurate and reliable deformation measurements are the main pillar of materials testing. Films produced by extrusion blowing process represent a real issue in their mechanical characterization. This is because of their relative fragility and low thickness. Actually, standard methods usually result to an uncertain strain definition leading to doubtful properties determination. In this work, two methods have been adopted in order to obtain the stress strain curve and investigate the tensile properties. The first is using experimental strain and the second using a non-contact full-field strain measurement technique based on three-D Digital Image Correlation (DIC). Test specimens are about PLA film and films with 1, 2 and 5 wt.% of palm fiber. All films were characterized by tensile testing along their machine direction (MD) and transverse direction (TD). A comparison of the young modulus of films using conventional method for the strain computation and using three-D DIC was done to evaluate the error in the stiffness determination. Furthermore, the analysis of the strain field distribution during the tensile test was carried out to locate zones with defects or with lower thickness through following zones with strain concentration.