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Characterization of ageing behaviour of environmentally acceptable lubricants based on trimethylolpropane esters

: Hahn, S.; Dott, W.; Eisenträger, A.


Journal of synthetic lubrication 23 (2006), Nr.4, S.223-236
ISSN: 0265-6582
Fraunhofer ITEM ()
infrared; organic ester; biodegradable base stock; hydraulic system; gear; nuclear magnetic resonance spectroscopy; liquid chromatography

Large amounts of lubricants having strong environmental effects are released into the environment. This has led to the development of so-called environmentally acceptable lubricants based on synthetic and/or native esters. The aquatic toxicity of these lubricants is low and they are readily biodegradable. However, the biodegradation rate can be reduced after application.
The aim of this study is to understand the lower biodegradation rate and the processes occurring during application. The changes are quantified using elemental analyses, high performance liquid chromatography with evaporative light scattering detector and mass spectrometer, as well as a combined screening method consisting of Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and electrospray ionization mass spectrometry.
The results of chemical analyses indicate that the main components are cracked, and double bonds of the main components are eliminated by oxidation causing polymerization effects. The intensity of these effects is dependent on the kind of use and the presence of additives. These modifications are responsible for the changes in the ecological and technical characteristics.