The Chemical Effects of Nitrogenous Substances in Two Different Grades of PVDF Used in Offshore Applications

ABSTRACT 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.