M. Zinbo

Regeneration of Amine in Catalytic Inhibition of Oxidation

Kinetic and mechanistic investigations of decomposition of O-sec-hexadecyl- and O-3-heptyl-4,4′-dioctyldiphenylhydroxylamines showed that at 120 and 140°C these compounds rapidly decompose to yield 4,4′-dioctyldiphenylamine. These results suggest that in the catalytic inhibition of oxidation by aromatic secondary amines or corresponding nitroxide radicals at elevated temperatures the decomposition of O-sec-alkyldiarylhydroxylamines leads to regeneration of the parent aromatic secondary amine.

Thermogravimetry of filter-borne diesel particulates

Abstract A direct thermogravimetric (TG) method is described for determining the percentage of volatile components in filter-borne diesel particulates. The procedure gives a quick estimate of total solvent extractable hydrocarbon components. A silica gel fractionation/size exclusion Chromatographic (SGF/SEC) procedure has also been developed to analyze further the solvent-extractable hydrocarbons of the particulates. The solvent extraction SGF/SEC procedure determines the contribution of lubricating oil and unburned fuel to particulates emitted from diesel engines. Results from this study indicate that the TG method yields a comparable measure of adsorbed hydrocarbons with those obtained by solvent extraction.

Inhibition of Oxidation by ZDTP and Ashless Antioxidants in the Presence of Hydroperoxides at 160°C - Part I

Reactions of zinc dialkyldithiophosphates (ZDTP) in the presence of hydroperoxides have been further investigated using a model n-hexadecane oxidation system at 160°C. Results obtained with selected primary and secondary alkyl ZDTP added alone and in combination with 2,6-di-tert butyl-4-methylphenol suggest that substantial differences exist between the reactions of these two types of ZDTP with regard to both hydroperoxide decomposition and radical trapping. The best overall oxidation control in the presence of excess hydroperoxides has been provided by i-C3ZDTP in combination with a radical trapping inhibitor. Presented at the 40th Annual Meeting in las Vegas, Nevada May 6–9, 1985

On The Chemical Composition and Origin of Engine Deposits

Knowledge of the chemical composition of engine deposits is essential to establishing the mechanisms of deposit formation and to understanding the influence of in-cylinder deposits on such problems as ORI and increased hydrocarbon emissions. Of particular concern is the identification of those deposit components which may be promoting deposit accumulation by functioning as binders.

Characterization of fluoroelastomer networks: II. SEC, FTIR, and ODR analysis

The role of an accelerator in the nucleophilic cure of fluorocarbon compounds was further examined by preparing materials without a crosslinker. Under the previously used curing conditions, ODR reveals the formation of a secondary, accelerator-induced network that is unstable at slightly higher temperature, i.e., ≥190°C. Increased crosslink density and color are observed with the cure time, indicating slow curing reactions and likely formation of conjugated unsaturation. SEC of selective solvent-soluble fractions derived from specimens obtained from the key cure stages shows initially a falling refractive-index response. However, this change is followed by a shift in MWDs toward lower average molecular weights. On the other hand, infrared examination shows a continuous increase in the 1718 cm−1 absorption, but no major presence for the 1680 cm−1 absorption seen in the previous study in the presence of a crosslinker. The concurrent increase in the 3114 cm−1 peak confirms the presence of a CFCH double bond. The solvent-soluble portions and bulk specimens have very similar infrared features.

Thermogravimetry of filter-borne gasoline engine-out particulates

Abstract A thermogravimetric (TGA) method has been developed to determine the percentage of unburned engine oil, carbon black, and inorganic residue for gasoline (petrol) engine-out particulates. In general, the range of recent gasoline engine-out particulate mass emissions is 5–20 mg per mile from the US EPA Urban Dynamometer Driving Schedule (UDDS) test procedure (11.1 miles per test). To make TGA measurements possible with such a low particulate mass emission level, each diluted exhaust particle sample (approx 1–3mg) was collected on an ultra-thin polytetrafluoroethylene (PTFE) membrane filter (thickness, 25 μ m, pore size, 2 μm) over the duration of four consecutive EPA UDDS test procedures, which was 0.3–0.5% of the total particulate mass emitted. This method can be very useful for providing a quick evaluation of unburned oil at the relatively low engine-out emission levels needed for improved catalyst durability.

Determination of engine oil volatility by thermogravimetry

Abstract A TG method for determination of the volatility of engine oils was developed as an alternative laboratory test to the Noack method (DIN 51581). The method involves standardizing a TG system with tetracosane (C 24 H 50 )) and determining the relative evaporative loss of engine oils at the heating time of 30% tetracosane weight loss under the standardized TG conditions. The evaporative loss values for 48 engine oils of different viscosity grades were determined by this TG method and compared with corresponding values determined by the Noack method. The relative standard deviation obtained for an SAE 5W-30 multigrade oil was 4.1% ( n = 8).

Gas-Liquid Chromatography of Oxygenated Compounds Related to the Autoxidation of n-Hexadecane

Abstract Gas chromatography has been utilized for analysis of a series of compounds related to n-hexadecane autoxidation. Several stationary phases have been tested and Silar-10C has been chosen for the separation of the C16 oxidation products. The selection was based on the thermal stability of the stationary phase and the resolution among the C16 compounds. Relative retention data obtained for selected oxygenated compounds and some of their trimethylsilyl derivatives are reported. Gas chromatographic analysis of reaction products from the autoxidation of n-hexadecane is then discussed.