16.1 Introduction

Nowadays, polymer-based materials are at the centre of applications where they are frequently subjected to temperature variations and also to gas pressures ranging from a few MPa to 100 MPa. In particular, in the petroleum industry, taken here as an example, the transport of petroleum fluids is done using flexible hosepipes. These hosepipes are made of extruded thermoplastic or rubber sheaths and reinforcing metallic armour layers. The type of transported fluids (which may contain important amounts of dissolved gases) and the operating temperature and pressure, dictates the composition of the hosepipe sheath ( e.g. polyethylene (PE) or polyamide (PA) and/or poly(vinylidene fluoride) (PVDF or PVF ₂)). However, these thermoplastic polymers, like elastomers, are not entirely impermeable and undergo sorption/diffusion phenomena. A rupture of the thermodynamic equilibrium after a sharp pressure drop may eventually damage the polymer components. Gas concentration in the polymer, together with temperature gradients, can cause irreversible explosive deterioration of the polymeric structures. This blistering phenomenon, usually termed as explosive decompression failure (XDF) process, is actually very dramatic for the material. The resistance to physical changes is related to the influence of the gas polymer interactions on the thermophysical properties of the polymer. The estimation of the gas sorption and of the concomitant polymer swelling as well as the measurement of the thermal effect associated with the gas polymer interactions...