Magnetorheological fluid durability test—Organics analysis

This report describes the analytical techniques used to characterize the organic fluid components of certain magnetorheological fluids (MRFs) which had been subjected to durability testing. Samples of MRF subjected to 540 and 108 h of service in a MRF fan clutch on a test stand were characterized along with neat and unused materials for comparison. The results indicated a surprising lack of oxidation of the poly-α-olefin (PAO) with only a small decrease in the molecular weight of one of the oligomers of the mixture. An increased amount of olefinic bonds was detected in the used fluid which suggests a mechanism for some of the chemical changes observed in the material.