The group of polyaryletherketones (PAEK) within thermoplastic polymers, including PEEK (polyetheretherketone) and PEKK (polyetherketoneketone) polymers, is of growing interest in a wide range of applications that demand superior mechanical strength and retention of physical properties at high temperatures and pressures. Important applications include downhole materials in oil&gas drilling and fracturing, artificial vertebrae and braces in medicine, and 3D printing. The demand for higher temperature and long term applications keeps growing, along with the quest for improved mechanical performance. Blends of PEEK and PEKK with polybenzimidazole (PBI) are of interest due to their improved high-temperature stability and wear properties. However, the blends are taking up more water and brines than pure PEEK and PEKK. Water and salts have been identified as the culprits of degradation processes taking place in the polymers. Therefore, it is important to better understand the uptake of water and salts and their location within the polymer networks. The changes of PBI and its PEEK- and PEKK-blends (50:50 wt%) after immersing them in liquid H2O and D2O, and exposing them to D2O steam at elevated temperatures and pressures have been investigated by multinuclear solid-state NMR and IR spectroscopy.1,2 Macroscopic morphological and chemical changes on the molecular scale which take place upon high-temperature steam-treatment and the extent and reversibility of the moisture uptake have been determined.1,2 Interactions and reactions of water, steam, and aqueous solutions of LiCl and ZnBr2 with the functional groups of the polymer components have been studied using D2O in combination with IR, 1H wideline, 2H, 7Li, and 79Br MAS, as well as 13C and 15N CP/MAS NMR spectroscopy. Different locations and types of water and protons in the blends will be described and proof will be presented that PBI is mainly responsible for water and salt uptake into the blends.

Moisture distribution in PEEK, PEKK, PBI, and their blends: A multinuclear solid-state NMR study

253rd National Meeting (2017)

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