Radiation-Induced Gas Evolution from Commercial Lubricant Base Oil

Radiation-induced evolved gases for 20 commercial lubricant base oils were measured at room temperature. Samples were irradiated under vacuum by ⁶⁰Co gamma rays at a dose rate of 1 Mrad/h up to 1000 Mrad for mineral oils and ester lubricants, and 3000 Mrad for aromatic lubricants. The evolved gas was measured by means of gas chromatography. The G values (number of gas molecules liberated per absorbed energy of 100 eV) of total evolved gases are 2.8 for liquid paraffins, 1.4 for paraffinic neutral oils, 1.5 to 1.9 for esters, 0.26 to 0.56 for alkyl diphenyl ethers, and 0.005 for phenoxy-phenoxydiphenyl