Morphological changes of polyamide 11 through the corrected inherent viscosity plateau

Abstract

AbstractThe pressure barrier is one of the layers that compose flexible pipes used for oil and gas exploitation. It is made from a thermoplastic that must endure harsh operation conditions keeping its properties during the projected lifetime. Polyamide 11 is used when operating temperatures are below 80°C. Although polyamides' aging chemical mechanisms are well established in the literature, their mechanical behavior is defined by deformation processes that, in turn, depend on the polymer molecular structure. The dominant aging mechanism, hydrolysis, has been used by industry as a parameter for lifetime evaluation. Different morphological arrangements may occur following chain scission depending on the operating environment, leading to line failure or unnecessary substitution. The complex combination of parameters affects the aging processes, chain scission, morphological changes, and, consequently, mechanical behavior. Understanding the role of environmental parameters such as pH, acidic content, among others, is crucial to improving the model used. In this context, this work evaluates the aging of PA11 in two fluids with different acid concentrations but the same pH. The goal is to assess the impact of the amount of acid molecules on the polymer structure at 120°C and quantify the aging of PA11 using acceptance criteria methods.