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Low-temperature rheology and thermoanalytical investigation of lubricating oils: Comparison of phase transition, viscosity, and pour point

Conrad, Andreas; Hodapp, Annika; Hochstein, Bernhard; Willenbacher, Norbert; Jacob, Karl-Heinz

Abstract:
According to the ASTM D97, the pour point is the temperature below which petroleum products cease to flow. To evaluate the relevance of pour point measurements for synthetic lubricating oils, we investigated the crystallization, melting temperature and low-temperature flow behavior of one mineral and five synthetic lubricating oils. The classification of three groups emerged from this process. The formation of paraffin crystals in mineral oils (I) below the crystallization temperature causes shear-thinning behavior and a yield point. The crystallization temperature determined in the thermal analysis and rheology correlates well with the pour point. Synthetic lubricating oils, which solidify glass-like (II), exhibit a steady viscosity increase with falling temperature. The temperature at which viscosity reaches 1000 Pas corresponds well to the pour point. Synthetic oils, especially esters, with complex crystallization behavior (III), exhibit supercooling depending on the shear rate and cooling conditions. For these lubricating oils, the pour point provides no information for low-temperature applicability.


Verlagsausgabe §
DOI: 10.5445/IR/1000139349
Veröffentlicht am 29.10.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Mechanische Verfahrenstechnik und Mechanik (MVM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 2075-4442
KITopen-ID: 1000139349
Erschienen in Lubricants
Verlag MDPI
Band 9
Heft 10
Seiten 99
Nachgewiesen in Web of Science
Scopus
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