Proper Antioxidant Selection for API SH by Statistical Evaluation in a New Sequence IIIE Screening Test

Mazzamaro, G.; Hutchings, M.; Vargo, M. W.; Evans, Slayton A.; Cassidy, D H

doi:10.4271/940793

Cited by 10 publications

(4 citation statements)

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“…A similar system was adopted later in Europe. With the application of the ACC Code of Practice, the commonly used concentration of alkylated diphenylamine antioxidants in the oil was increased in order to pass Sequence IIIE viscosity control requirements [106]. When the Sequence IIIE, of 64 h test duration, was replaced by the Sequence IIIF, of 80 h duration, with ILSAC GF-3 (API SL) for 2001 model year vehicles, the trend to use higher concentrations of ashless antioxidants continued, especially under the higher temperature conditions and increased lubricant exposure to NO x in the blow-by gases of the Sequence IIIF engine.…”

Section: Antioxidant Technology For Passenger Car Engine Oilsmentioning

confidence: 99%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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Thermally induced hydrocarbon oxidation is a self-accelerating autoxidation process and is divided into 'low'-, 30-120 • C, and 'high'-, >120 • C, temperature phases. The first has four stages -induction of radical chain reactions, propagation, branching and then termination. Mechanisms of these processes are described and discussed. Differences in hydrocarbon reactivity are related to molecular structure. For hydrocarbon oxidation >120 • C, the first stage is the same as low-temperature oxidation but with reduced selectivity and increased reactivity; second, the oxidation phase becomes diffusion controlled as hydrocarbon viscosities increase from progressive polycondensation of higher molecular weight products, causing varnish and sludge formation. Base oil oxidation stabilities depend upon their derivation, whether solvent neutral, hydrocracked or synthetic, and their response to antioxidant treatment. Lubricant oxidation control focuses on radical scavengers and hydroperoxide decomposers and their synergistic mixtures.Engine oils increasingly use phenolic and aminic antioxidants as radical scavengers with organometallic complex antioxidants. Sterically hindered phenols substituted at 2-and 6-positions by t-butyl groups are particularly effective, reacting successively with peroxy radicals to form stable cyclohexadieneone peroxides. Secondary amines as either two aryl or phenyl and naphthyl groups are very effective at eliminating four peroxy radicals per molecule. They are more effective by a ratio of 4:2 than the sterically hindered phenols below 120 • C. At higher temperatures a catalytic cycle is suggested as an extended stabilisation mechanism. Transition metal ions with two valence states, Fe 2+/3+ , Cu 1+/2+ , etc. as trace quantities of metal soaps catalyse/retard autoxidation according to concentration and/or combination of metals. They catalyse or inhibit oxidation by complexing and decomposing hydroperoxides or can also oxidise peroxy radicals and reduce alkyl radicals to inert products. Organomolybdenum complexes such as molybdenum dialkyldithiocarbamates, MDTC, are increasingly used to stabilise engine lubricants particularly because of synergy with other antioxidants such as alkylated diphenylamines. 107 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,

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Section: Antioxidant Technology For Passenger Car Engine Oilsmentioning

confidence: 99%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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“…Rohrbach, Hantblin, and Ribmid The results found for various types of greases (different thickeners and different antioxidants) match well with theoretical curves derived from Eq. (11). Applying this equation, it follows that the slope is on average 18 K log OIT = 18( i) -b and only the shift of the straight line (b) depends on the grease type and the additivation.…”

Section: Results: Studies Of Greases: Benefits Of Antioxidantsmentioning

confidence: 99%

“…According to the Arrhenius law, the kinetic rate constant k of the thermal degradation of the hydrocarbon is a function of the temperature: From Eq. (11) it follows that only the shift of the straight line, that is, Const(kHCmax;AOO), depends on the additivation and not its gradient ( Figure 8). This indicates that the kinetics of lubricant degradation, as assessed by the OIT, are not influenced by antioxidants.…”

Section: Eq (8) Can Be Transformed and Simplified Tomentioning

confidence: 96%

Benefits of antioxidants in lubricants and greases assessed by pressurised differential scanning calorimetry

2005

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The long-term thermo-oxidative stability of lubricants and greases is a prerequisite to meet today's 'stay in grade' and extended drain interval requirements. To achiezie this goal, there is a need for a better understanding of thermo-oxidative lubricant degradation and of how antioxidants can affect this process. In this paper a tuio-stage degradation model is discussed. Primary degradation leads to the formation of very reactive species such as radicals and peroxides. These are the precursors for generating secondary degradation products, such as oligomers, sludge, or deposits. By applying the theory of reaction kinetics and the Arrhenius law, quantitative correlations may be derived between oxidation induction time (OIT) and temperature, and between OIT and antioxidant treat level. Pressurised differential scanning calorimetry (PDSC) data confirm these theoreticalfindings and demonstrate the benefit of the addition of aininic antioxidants i n comparison with high-molecular-weight hindered phenolic antioxidants.

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“…Instead of the Noack test, we are presently evaluating a modification of the bulk oil aging test procedures used by many engine oil formulators for the assessment of the stability of engine oil candidates. 4 Obviously the molecular weight on its own is not a good predictor of phosphorus emissions. Regarding their activity as anti-wear agent, we conclude from engine testing that zinc-free, ashless anti-wear additives can reliably and advantageously be used for the formulation of robust medium-or low-ash engine oils.…”

Section: Effect Of the Formation Of A Filmmentioning

confidence: 99%

Volatility of phosphorus-containing anti-wear agents for motor oils

Ribeaud

2006

Lubrication Science

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Replacing zinc dithiophosphate (ZnDTP) with ashless anti-wear alternatives will lead to a significant reduction of ash and give more flexibility in the use of metallic detergents. The question of the contamination of exhaust gas after treatment devices by volatile phosphorus-containing compounds has recently been raised. We report the results of investigations on the amount of gaseous emissions of phosphorus released from engine oils formulated with a range of phosphorus-containing anti-wear additives. To relate the structure of additives to the observed phosphorus emissions, we have investigated a variety of phosphorus-containing anti-wear agents, metalcontaining as well as ashless. We have used established and new laboratory tests in addition to measurements on fired engines to assess the phosphorus emissions. We discuss the anti-wear capability and friction control of these phosphorus-containing additives. We conclude that it is possible to formulate zinc-free, low-ash engine oils which will control wear and corrosion and not release more phosphorus into the exhaust gas after treatment systems than the traditional ZnDTP based oils.

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Proper Antioxidant Selection for API SH by Statistical Evaluation in a New Sequence IIIE Screening Test

Cited by 10 publications

References 0 publications

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Benefits of antioxidants in lubricants and greases assessed by pressurised differential scanning calorimetry

Volatility of phosphorus-containing anti-wear agents for motor oils

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