J Fail. Anal and Preven.(2011)11: 158-16 Fig 2 FT-IR spectra of (a)fresh and(b) used grease 46050 m223763135 597 103802 1n1837 1377.2 146096 2924.12 (a)00300302000020008001001400120010090060040 1000 177449154107 129952 7130 13T09 1460.17 285463 292449 400003600320029002400200018001600140012001000 the hydrogen peroxide and secondary alkyl free radicals, as R"+h-Rh (Eq4) shown in reactions(2)and(3). In this way, the reactions R·+R·→R-R would not cease until the termination of the chain occurred via reaction with the hydrogen free radical, and/or mutual When the temperature increased the hydrogen peroxide coupling, as shown in reactions(4)and (5), respectively. (ROOH) decomposed into alkyl-oxygen radicals(RO) R+O→ROO (Eg 2)and hydroxyl radicals(HO), as shown in reaction (6) ould fur ROO·+RH→ROOH+R (Eq 3) produce the final alkyl radicals (R,), as shown inthe hydrogen peroxide and secondary alkyl free radicals, as shown in reactions (2) and (3). In this way, the reactions would not cease until the termination of the chain occurred via reaction with the hydrogen free radical, and/or mutual coupling, as shown in reactions (4) and (5), respectively. R þ O2 ! ROO ðEq 2Þ ROO þ RH ! ROOH þ R ðEq 3Þ R þ H ! RH ðEq 4Þ R þ R ! R
R ðEq 5Þ When the temperature increased the hydrogen peroxide (ROOH) decomposed into alkyl-oxygen radicals (RO• ) and hydroxyl radicals (HO• ), as shown in reaction (6), below. These groups could further react with RH to produce the final alkyl radicals (R• ), as shown in Fig. 2 FT-IR spectra of (a) fresh and (b) used grease sample 160 J Fail. Anal. and Preven. (2011) 11:158–166 123