Lube-Tech
that TMP DO has a lower mass with nearly the same polarity will decrease the npi. Furthermore, the smaller molecular size compared to TMP TO also reduces the elastomer compatibility.
Summary Different ester base oils show a fundamentally different sealing compatibility. For a prediction of the compatibility, three different factors can be considered: polarity, viscosity and double bonds. Polar polymers are more likely to be attacked than non-polar ones. Esters with a higher viscosity show better compatibility due to the higher molar volume. In terms of double bonds, it can be seen that unsaturated esters are less prone to swelling.
Taking a look at different polymer types, FKM polymers generally show very good resistance to ester oils and are therefore the first choice with regard to resistance. Other materials, such as EPDM, have proven to be unsuitable. Polymers like NBR and HNBR show a lower compatibility than FKM polymers but taking the above-mentioned factors into account, it is possible to find a suitable ester base oil.
Elastomer compatibility should also be considered if an existing lubricant formulation is modified as changes of the base oil might have a significant impact. An example are existing systems for Stern Tubes which have to be converted to Environmentally Acceptable Lubricants (EAL). The change to a new, biodegradable ester base oil or sometimes even a mixture of two is common in this application. When selecting a new base oil, particular attention has to be put on the low-viscosity component as it has a decisive influence on the elastomer compatibility of the entire system.
Bibliography
Andrew Flórez, Gero Burghardt, Georg Jacobs,. 2016. Influencing factors for static immersion tests of
www.peter-greven.de
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.138 page 6
compatibility between elastomeric materials and lubricants. Polymer Testing. 2016, Vol. 49. Rinnbauer, Meike. 2007. Technical Elastomers. München : sv corporate media GmbH, 2007. Starmer, P. H. 1993. Swelling of Nitrile Rubber Vulcanizates- Part 3: Factors Affecting Maximum Swelling. Journal of elastomers and plastics. 1993, Vol. 25, 3. Torbacke, M. and Johansson, A. 2005. Seal Material and Base Fluid Compatibility: An Overview. Journal of Synthetic Lubrication. 2005, Vol. 22, 2. Van der Waal, G. 1985. The relationship between the chemical structure of ester base fluids and their influence on elastomer seals and wera characteristics. Journal of synthetic lubrication. 1985, Vol. 1, 4. Vidović, Elvira. 2014. Development of lubricating oils and their influence on the seals. Goriva i maziva. 53, 2014, Vol. 3.
Sustainable,
biodegradable synthetic esters.
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