Among greases used in Industry,metal soap greases have nearly 75 percent share. They are also used in Nuclear Industry. In Nuclear Industry they are susceptible to gamma radiation. In one of such application, the grease thickener degraded leading to fluidisation and subsequent polymerization of the oil and degraded thickener.
FTIR-ATR analysis of the degraded material indicated presence of a strong peak at 1713 1/cm wave number indicating oxidation of the grease under radiation (formation of C=O bond).
FTIR-ATR analysis of the fresh grease also indicated the grease to be Li-Ca stearate grease.
Dropping point of the fresh grease was measured to be 150 deg C whereas dropping point of irradiated grease ( 100 Mrad) as observed to be 132 deg C.It indicates that with degradation in thickener matrix, dropping point decreases.
FTIR-ATR analysis is a very useful tool to identify the grease and its degradation in presence of radiolytic oxidation.
In the next post I will share the FTIR -ATR of degraded grease