Assessment of chemo-mechanical couplings in polymer matrix materials exposed to thermo-oxidative environments at high temperatures and under tensile loadings

The present paper is concerned with the experimental assessment of chemo-mechanical couplings in a polymer matrix material exposed to thermo-oxidative environments at high temperatures and under pure tensile loadings. A model developed within the thermodynamics of irreversible processes (TIP) states that oxygen reaction-diffusion in the polymer matrix should be affected by the strain tensor and its spatial gradient; the model motivates the design and the development of the experimental assessment, which is done by ultra micro-indentation (UMI) elastic modulus (EIT) measurements carried out - at room temperature - on unnotched and notched 977-2 polymer samples thermo-oxidized under tensile loadings.For the material and the loading conditions of the present research the EIT profiles are not influenced by the applied strain or by the strain gradients which develop close to the sample notches.