Online lubricant degradation monitoring using contact charging of polymers.

Just in time for an oil change : As verified by parallel chemical analyses showing the extent of oxidation, a single (tribo)electric signal reflecting the contact charging between an oil-dipped paper and a common polymer can predict the time for an oil change for engine oils. The method is a simple and cost-effective one - it can help protect the environment by preventing the premature or late change of oil in engines and prevents machine wear and economic losses. [Display omitted] • Triboelectric signal generated from two contacting polymers can be used to monitor the lubricant oil condition. • A parallel spectroscopic analysis of oil proves that the triboelectric signal follows the course of oil oxidation. • The concept overall is applicable (in comparison to complex chemical analysis) and general (uses common polymers in contact). Lubrication of machine parts is necessary to prevent friction and wear in machine operation. However, oxidation of lubricants upon operation changes their chemical and physical properties and causes lubrication performance to deteriorate. Besides, one liter of wasted/used lubricant oil can contaminate a million liters of water. Current methods for the timely detection of oil deterioration lack practicality. Here we show simple, a triboelectrification-based method for oil degradation monitoring, in which the oxidation can be monitored by the changes in the contact charging (and separation) signals of oil-dipped cellulose and a common polymer tapped to each other. The commercial and base oil samples are oxidized at 100–200 °C for up to 80 h, simultaneously monitored by ATR-FTIR and the triboelectric method. The results show that a 40–90% decrease in the triboelectric open-circuit potentials in the presence of oxidized oil can directly indicate the start of oil oxidation without other accompanying analyses. [ABSTRACT FROM AUTHOR]