Ageing of PA 11 Pipes in CO2 Medium: A Tool to Predict Their Residual Lifetime

The study of polyamide 11 hydrolysis in acid medium has a great importance taking into account the presence of CO2 pressure in the fields. Experimentally we have put in evidence that CO2 accelerates PA 11 hydrolysis and shift the equilibrium towards high conversions. Theoretically, two mechanisms can be involved in the CO2 effect on hydrolysis: - a catalytic effect by H+ ions (acceleration of the hydrolysis reaction); - an amine scavenging by CO2 (shift of the equilibrium towards high conversion) From this mechanistic scheme we propose a kinetic model. Then, we have built a computer program allowing to made all the calculations needed in practice by the users as the average molar mass and the residual lifetime for given conditions.