Influence of thermo-oxidative degradation on the biodegradability of lubricant base oils

摘要

The paper addresses the problem of how the thermo-oxidative changes in the chemical structure influence the biodegradability of lubricating base oils. The tests were conducted using synthetic polyolesters, polyalphaolefins (PAO 4) and blended polyolesters with 30 wt % of PAO 4. Oil biodegradability was evaluated in accordance with the International Standards Organization (ISO) 14593 test. The thermo-oxidative degradation consisted of a 24-hour exposure of the oil samples to the temperature of 150℃ in a universal test apparatus at an air flow rate of 15 L/hour. The results have revealed that the thermo-oxidative degradation of the chemical structure produces changes in the physico-chemical properties of the base oils and improves biodegradability. The polyolester oils tested were found to be readily biodegradable both before and after thermo-oxidative tests. PAO 4 oil and its blends with polyolester oils could not be classified as readily biodegradable. The thermo-oxidative changes in their chemical structures can exert a positive effect on their biodegradability.