Real‐time Raman spectroscopy measurements to study the uniaxial tension of isotactic polypropylene: a global overview of microstructural deformation mechanisms

Micro‐Raman spectroscopy was used to investigate the main deformation micromechanisms of isotactic polypropylene uniaxially stretched at constant temperature (T = 30 °C) under a constant true strain rate ( = 5.10−3 s−1). To accurate measurements namely to be free of the recovering phenomenon which causes in most of the cases interference during post‐mortem analysis, we introduced a new experimental setup combining a Raman spectrometer with a tensile machine piloted by the VidéoTraction™ system. Microstructure is described by essential parameters such as the crystallinity index, the macromolecular orientation both in the crystalline and the amorphous phase, and distribution of the internal stress at the chemical bonds scale. For each, a well‐tried Raman spectral criterion was used. Cross‐checking of these results, obtained with a minimum of tensile tests, allows a more complete understanding of the deformation micromechanisms of semi‐crystalline polymer.