Color stabilization

Detergent Additives. Diesel engine deposits ate most troublesome in the fuel dehvery system, ie, the fuel pump and both fuel side and combustion side of the injectors. Small clearances and high pressures mean that even small amounts of deposits have the potential to cause maldistribution and poor atomization in the combustion chamber. The same types of additives used in gasoline ate used in diesel fuel. Low molecular weight amines can also provide some corrosion inhibition as well as some color stabilization. Whereas detergents have been shown to be effective in certain tests, the benefit in widespread use is not fully agreed upon (77). 

Triisopropan olamine is used in natural mbber cross-linking and as a color stabilizer for polyethylene formulations. Chain termination of polybutadiene with triisopropan olamine gives improved cold-flow properties. 

Resins are also used for permanent tooth-colored veneers on fixed prostheses, ie, crown and bridges. Compositions for this application include acryflcs, vinyl—acryflcs, and dimethacrylates, as well as silica- or quartz-microfilled composites. The resins are placed on the metallic substrates of the prostheses and cured by heat or light. These resins are inexpensive, easy to fabricate, and can be matched to the color of tooth stmcture. Acrylic facings do not chemically adhere to the metals and are retained only by curing the resin into mechanical undercuts designed into the metal substrate. They have relatively low mechanical strength and color stability, and poor abrasion and strain resistance they also deform more under the stress of mastication than porcelain veneers or facings. 

Aromatic Polyester Resins. A number of attempts to commeicialize aromatic polyesters have been made. However, for reasons such as moldabiUty, clarity, and color stability, significant market share has never been achieved. 

Several techniques can be used to separate phenol. Solvent extraction using gas oil or lube oil (process MSAs Sj and S2, respectively) is a potential option. Besides the purification of wastewater, the transfer of phenol to gas oil and lube oil is a useful process for the oils. Phenol tends to act as an oxidation inhibitor and serves to improve color stability and reduce sediment formation. The data for the waste streams and the process MSAs are given in Tables 3.4 and 3.5, respectively. 

In addition, some of the nitrogen compounds end up in light cycle oil (LCO) as pyrolles and pyridines [5]. These compounds are easily oxidized and will affect color stability. The amount of nitrogen in the LCO depends on the conversion. An increase in conversion decreases the percentage of nitrogen in the LCO and increases the percentage on the catalyst. 

The Atlas Type FDA-IR Fadeometer is used primarily to check and compare color stability. Besides determining the stability of various pigments needed to provide both standard and custom colors, the Fadeometer is helpful in preliminary studies of various stabilizers, dyes, and pigments compounded in plastics to prolong their useful life. 

Color Urea, melamine, polycarbonate, polyphenylene oxide, polysulfone, polypropylene, diallyl phthalate, and phenolic are examples of what is needed in the temperature range above 200°F (94°C) for good color stability. Most TPs will be suitable below this range. 

Preservatives generally fall into four categories. There are ultravi-olet/UV light absorbers (to prevent light from creating harmful and bad-tasting toxins), color stabilizers, antioxidants, and antimicrobials. 

Whereas nonionic ethylene oxide adducts discolor badly on contact with sodium hydroxide, phosphate derivatives of these nonionics exhibit good color stability even under these conditions. But in the presence of strong acids poly-oxyethylated phosphate esters undergo hydrolysis to the base nonionic and phosphoric acid. However, the free surface-active acids by themselves show little tendency to hydrolyze. They have a pH value of 2 in aqueous solution. 

An electric conductive rubber base containing carbon black is laminated with an electric conductive cover layer of phosphoric acid ester plasticizer and other ionic surfactants to prepare antistatic mats, where the covers have colors other than black. It is also reported that alkyl acid phosphates act as color stabilizer for rubber. Small amounts of phosphate esters are helpful in restoring reclaimed rubber to a workable viscosity [284,290]. Esters of phosphoric acid are used in the production of UV-stable and flame-retarded alkylbenzenesulfonate copolymer compositions containing aliphatic resins and showing a high-impact strength... 

Vareltzis, K.R and Buck, E.M., Color stability and sensory attributes of chicken frankfurters made with betalains and potassium sorbate versus sodium nitrite, J. Food Protect., 47, 41, 1984. 

Four anthocyanin species exist in equilibrium under acidic conditions at 25°C/ according to the scheme in Figure 4.3.3. The equilibrium constant values determine the major species and therefore the color of the solution. If the deprotonation equilibrium constant, K, is higher than the hydration constant, Kj, the equilibrium is displaced toward the colored quinonoidal base (A), and if Kj, > the equilibrium shifts toward the hemiacetalic or pseudobase form (B) that is in equilibrium with the chalcone species (C), both colorless." - Therefore, the structure of an anthocyanin is strongly dependent on the solution pH, and as a consequence so is its color stability, which is highly related to the deprotonation and hydration equilibrium reaction constant values (K and Kj,). 

The color stability of strawberry syrup with or without fortification with anthocyanins from black currants (cyanidin and delphinidin 3-glucosides and 3-rutino-sides) and/or AA with levels equivalent to those existing in black currant syrup was investigated. Black currant-fortified strawberry anthocyanins showed higher stability the addition of AA diminished stability. ... 

Anthocyanins were decolorized at pH 3.0 by the addition of sodinm sulfite at the C-2 or C-4 of the chromophore, a reaction that was rapidly reversible on acidification. Snlfnr dioxide, EDTA, and a combination of snlfnr dioxide and EDTA exerted very small effects on the losses of anthocyanins in strawberry pnrees and juices during 10 wk of storage at -20°C. Conversely, the addition of snlfnr dioxide and storage at 20°C slowed the anthocyanin losses and concnrrently decreased the formation of polymeric componnds, especially in pnrees. EDTA had a slight effect on color stability. ... 

Houbiers, C. et al.. Color stabilization of malvidin 3-glucoside self-aggregation on the of flavylium cation and copigmentation with the Z-chalcone form, J. Phys. Chem. B, 102, 3578, 1998. 

BronUlard, R., The chemistry of anthocyanin pigments. 7. Origin of the exceptional color stability of the zebrina anthocyanin. Phytochemistry, 20, 143, 1981. 

Garcia-Viguera, C. and Bridle, P, Influence of structure on color stability of anthocyanins and flavylium salts with ascorbic acid. Food Chem., 64, 21, 1999. 

Malien-Aubert, C., Dangles, O., and Amiot, M.J., Color stability of commercial anthocyanin-based extracts in relation to phenolic composition protective effects by intra- and intermolecular copigmentation, J. Agric. Food Chem., 49, 170, 2001. 

Maccarone, E., Maccarrone, A., and Rapisarda, P, Color stabilization of orange fruit juice by tannic acid, Int. J. Food. Sci. TechnoL, 22, 159, 1987. 

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