As the polyamide 11 (PA11) present in flexible pipes for oil prospection is used, it also reacts with the fluid components in the oil so that not only the morphology of the polymer changes but also its properties. To see the extent of these chemical modifications and how they changed the original material, different techniques were employed, such as ATR-FTIR, DSC, TGA, and Melt-flow index (MFI), while the original sample was cut in half to measure if the direct contact with the fluid had a huge chemical influence. The results indicate that the degree of chemical changes in the PA11 part that was in direct contact with the fluid was higher, translated into the appearance of different molecules in the FTIR spectra (such as ethers, carbonates, and alkenes). These changes were also consistent with higher degradation of this half, leading to a region of higher crystallinity, which impacted the overall thermal properties of the polymer.

In this work, two different grades of poly(vinylidene fluoride) (PVDF) commonly used in offshore applications, one with 3% of dibutyl sebacate (DBS) plasticizer and the other a copolymer containing chlorotrifluoroethylene (CTFE), were subjected to an aging process in contact with a fluid containing hydrocarbons, pyridine, and aniline at high temperature for 90 days. For comparison, control experiments using the same hydrocarbon‐based medium without pyridine and aniline were performed for 7 and 30 days and evaluated by selected analyses, including mass variation and FTIR‐ATR. The samples were analyzed using Fourier transform infrared spectroscopy (FTIR), x‐ray photoelectron spectroscopy (XPS), mass variation measurements, tensile testing, and differential scanning calorimetry (DSC), while the greenish solid byproduct observed only during aging of PVDF 60512 was analyzed by Raman spectroscopy and energy dispersive x‐ray fluorescence spectrometry (EDXRF). PVDF 60512 exhibited a more pronounced response under the investigated conditions, including higher mass variation, more evident spectroscopic changes, and greater changes in mechanical and thermal behavior, whereas PVDF M800 showed comparatively less pronounced changes. The control experiments showed comparatively limited mass and FTIR‐detectable changes over the first 30 days relative to the N‐containing medium, supporting the distinct response observed under the complete aging condition. The presence of CTFE units may contribute to this behavior, although other differences between the commercial grades cannot be excluded. A possible reaction mechanism involving CTFE units was proposed to interpret the chemical changes observed in PVDF 60512.