Aging of polyetheretherketone (PEEK) and polyphthalamide (PPA) in polar and non-polar lubricant base oils

P. M. Ferreira, B. Trindade, M. Kalin

Polymer Testing 131 (2024) 108342 1-12

Abstract

The lubrication of high-performance polymers allows the more widespread use of these materials in mechanical systems. This work aims to study the compatibility of polyetheretherketone (PEEK) and polyphthalamide (PPA) with polar and non-polar lubricant base oils by inducing aging. Polymer discs were kept immersed in two polar synthetic esters, i.e., propylene glycol ester (PG) and trimethylolpropane ester (TMP), as well as in a non-polar synthetic oil, polyalphaolefin (PAO). Aging was carried out at room temperature and at 100 °C for 30 days. Samples were also aged in air at 100 °C to differentiate the effects of chemical and thermal aging. The chemical, morphological, thermal and mechanical properties of the aged samples were measured and compared to the unaged material. The results for aging in oils at 100 °C show the appearance of carbonyl-containing groups on the surfaces of both polymers, with consequent changes in their surface free energy, and an increase in the crystallinity and microhardness. The diffusion of oil molecules induced the oxidation of the polymers. PEEK was less affected by aging than PPA. The aging in PG ester at 100 °C revealed more pronounced effects among all the oils because of its polarity and its smaller molecule size, which led to an easier diffusion into the polymer matrix and plasticization.

URL: https://doi.org/10.1016/j.polymertesting.2024.108342

Keywords: polyetheretherketone, polyphthalamide, lubricants, PAO, esters, aging

Open access URL SLO: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=154703&lang=slv

Open access URL ENG: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=154703&lang=eng

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