Low-Temperature Rheology and Thermoanalytical Investigation of Lubricating Oils

  • 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,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.show moreshow less

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Metadaten
Author:Andreas ConradORCiD, Annika Hodapp, Bernhard Hochstein, Norbert Willenbacher, Karl-Heinz Jacob
DOI:https://doi.org/10.3390/lubricants9100099
ISSN:2075-4442
Parent Title (English):Lubricants
Subtitle (English):Comparison of Phase Transition, Viscosity, and Pour Point
Publisher:MDPI AG
Document Type:Article
Language:English
Date of first Publication:2021/10/06
Reviewed:Begutachtet/Reviewed
Release Date:2024/07/26
Tag:lubricating oil; mineral oil; synthetic oil; pour point; low-temperature rheology; DSC
Volume:9
Issue:10
Article Number:99
Pagenumber:12
institutes:Institut für Chemie, Material- und Produktentwicklung
Research Themes:Materialien & Produktionstechnik
Licence (German):Creative Commons - CC BY - Namensnennung 4.0 International
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