Abstract:The main products of the thermal‐oxidative degradation of p, p'‐di‐tert‐ octyldiphenylamine, phenothiazine and 3,7‐di‐tert‐octylphenothiazine (DODPA/PTZ/DOPTZ) in pentaerythritol ester at 200°C were isolated and identified. Recombination o f aminyl radicals giving various dehydrodimers and dehydro‐trimers is obviously the dominating reaction in the primary stage of antioxidant depletion during ageing of inhibited ester oils. Minor degradation products include quinone imines, quinones, sulphoxides, phenoxazine … Show more
“…Several classes of antioxidants are typically used in industry for the abovementioned purpose. 1,[14][15][16] Antioxidants inhibit specific steps in the free-radical oxidation process; hence, inhibition can occur during either the initiation or propagation steps of oxidation. [14][15] Scheme 1 shows the steps in the oxidation of organic materials by a free-radical chain mechanism.…”
Section: Introductionmentioning
confidence: 99%
“…To overcome the problems caused by the degradation of finishes, several additives are introduced to prevent or delay the reactions of oxidation and degradation. Several classes of antioxidants are typically used in industry for the above-mentioned purpose. ,− Antioxidants inhibit specific steps in the free-radical oxidation process; hence, inhibition can occur during either the initiation or propagation steps of oxidation. − Scheme shows the steps in the oxidation of organic materials by a free-radical chain mechanism. 1 Oxidation of Organic Materials by Free-Radical Chain Reactions…”
The thermal degradation of a polyol ester lubricant used as the main component of textile fiber finishes at
high temperature (i.e., 220 °C) has been studied to model the real-world degradation of finishes on fiber
manufacturing equipment. Chemical and physical analyses were performed on the thermally stressed lubricants
using a combined analytical technique to measure the progress of degradation in the lubricant. The effects of
two commonly used antioxidants in the fiber industry and two secondary arylamine antioxidants used in
turbine engine oil on the thermal behavior of the lubricants were investigated. Phenyl-α-naphthylamine (PAN)
shows a significant improvement in the thermal stability of the lubricant used in this study and could be
considered as a potential fiber finish antioxidant for the textile industry.
“…Several classes of antioxidants are typically used in industry for the abovementioned purpose. 1,[14][15][16] Antioxidants inhibit specific steps in the free-radical oxidation process; hence, inhibition can occur during either the initiation or propagation steps of oxidation. [14][15] Scheme 1 shows the steps in the oxidation of organic materials by a free-radical chain mechanism.…”
Section: Introductionmentioning
confidence: 99%
“…To overcome the problems caused by the degradation of finishes, several additives are introduced to prevent or delay the reactions of oxidation and degradation. Several classes of antioxidants are typically used in industry for the above-mentioned purpose. ,− Antioxidants inhibit specific steps in the free-radical oxidation process; hence, inhibition can occur during either the initiation or propagation steps of oxidation. − Scheme shows the steps in the oxidation of organic materials by a free-radical chain mechanism. 1 Oxidation of Organic Materials by Free-Radical Chain Reactions…”
The thermal degradation of a polyol ester lubricant used as the main component of textile fiber finishes at
high temperature (i.e., 220 °C) has been studied to model the real-world degradation of finishes on fiber
manufacturing equipment. Chemical and physical analyses were performed on the thermally stressed lubricants
using a combined analytical technique to measure the progress of degradation in the lubricant. The effects of
two commonly used antioxidants in the fiber industry and two secondary arylamine antioxidants used in
turbine engine oil on the thermal behavior of the lubricants were investigated. Phenyl-α-naphthylamine (PAN)
shows a significant improvement in the thermal stability of the lubricant used in this study and could be
considered as a potential fiber finish antioxidant for the textile industry.
“…Organic peroxides possess strong oxidative attack to other organic molecules and metallic materials. Aromatic amines [77,78], alkyl sulfides [79], and ZnDTP [80] are frequently employed to decompose peroxy radicals or peroxides. Peroxide decomposers are post-active AO that deactivate the active intermediates after the reaction with oxygen.…”
This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. The readers will be introduced to molecular sciences underlying lubrication engineering. Currently, lubricant chemistry, especially "additive technology", looks like a very complicated field. It seems that scientific information is not always shared by researchers. The cause of this is that lubrication engineering is based on empirical methods and focuses on market requirements. In this regard, engineering knowhow is held by individuals and is not being disclosed to scientific communities. Under these circumstances, a bird's-eye view of lubricant chemistry in scientific words is necessary. The novelty of this review is to concisely explain the whole picture of additive technology in chemical terms. The roles and functions of additives as the leading actors in lubrication systems are highlighted within the scope of molecular science. First, I give an overview of the fundamental lubrication model and the role of lubricants in machine operations. The existing additives are categorized by the role and work mechanism in lubrication system. Examples of additives are shown with representative molecular structure. The second half of this review explains the scientific background of the lubrication engineering. It includes interactions of different components in lubrication systems. Finally, this review predicts the technical trends in lubricant chemistry and requirements in molecular science. This review does not aim to be a comprehensive chart or present manufacturing knowhow in lubrication engineering. References were carefully selected and cited to extract "the most common opinion" in lubricant chemistry and therefore many engineering articles were omitted for conciseness.
This
work presents, for the first time, the evaluation on the oxidation
stability of synthetic oils for an aircraft engine using the rapid
small-scale oxidation test (RSSOT) method. Polyol ester lubricants
with and without additives were oxidized at 423 K and 7 bar. The pressure
drop plots show that during the first period of thermal degradation,
the consumption of oxygen is similar for both samples. This part corresponds
to the initiation steps of the mechanism of oxidation. Then, the curve
of the oil without additives reveals an increase in the depletion
of oxygen, corresponding to the kinetic propagation step. Because
of the presence of antioxidants, this phase is not observed for oil-containing
additives. The RSSOT method also allows us to quantify the time needed
for the ester base to produce enough free radicals in order to propagate
the mechanism of oxidation. A methodic comparison with other samples
containing the raw oil and one additive is also proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
