Resistance to oxidative degradation

The polymers also have excellent resistance to oxidative degradation, most chemicals other than strong bases and high-energy radiation. Exposure for 1500 hours to a radiation of about 10 rads at 175°C led to embrittlement but the sample retained form stability. 

The gasoline specification ASTM D-4814 requires gasoline which is marketed and sold to possess a minimum level of resistance to oxidative degradation. This resistance is determined by test method ASTM D-525 and is outlined below ... 

Lyons, J.E. and Elis, P.E., Catalytic Systems with Higher Resistance to Oxidative Degradation In Metalloporphyrins in Catalytic Oxidation, Ed. R. Sheldon, Marcel Dekker, New York, 1994, pp. 297-324. 

The Carbowax column is very sensitive to oxidation when the stationary phase is exposed to traces of water or air especially at temperatures above about 160°C. A new type of cross-linking has been reported to impart resistance to oxidative degradation of the stationary phase [5-7]. Two other phases which show promise are an oligo-(ethylene oxide)-substituted polysiloxane (glyme) and an 18-crown-6-substituted polysilox-ane [8]. The glyme column offers a polar phase with good operational conditions to a low of a least 20°C with the same selectivity of Carbowax. The crown polysiloxane selectivity is based on the interaction of the solute molecule with the cavity of the crown ether. 

The level of polyunsaturates in the hydrophobe of a cationic surfactant influences its liquidity and also its resistance to oxidative degradation and color formation [24, 37]. The higher the polyunsaturate level and consequently the iodine value, the higher the liquidity and the higher the aqueous concentration of a softener dispersion that can be achieved. Products with high or even modest degrees of unsaturation frequently require the addition of an antioxidant such as the hindered phenol derivatives, butylated hydroxy toluene and butylated hydroxy anisole [24, 25, 38]. 

ASA terpolymer is similar to ABS. This blend improves its resistance to oxidative degradation. It provides UV-resistant resulting in an excellent combination of color and property retention after outdoor exposure in both light and dark colors. There are three major markets for ASA building and construction, leisure and recreation, and automotive. 

In heterocyclic aromatic compounds, the ring containing electron-withdrawing substituents is more resistant to oxidative degradation. Both quinoline and 8-hydroxyquinoline give quinolinic (pyridine-2,3-dicarbox-ylic) acid (equation 160) [117, 459]. 

Films, coatings, adhesives, laminates outstanding in heat resistance, flame resistance, abrasion resistance, electrical iruulation resistance. resistance to oxidative degradation, high energy radiation and most chemicals (except strong bases) used in specialist applications. e.g.,Kapton, Vespel. 

Generally speaking, the electron-poor heterocycies are more resistant to oxidative degradation than are electron-rich systems - it is nsnally possible to oxidise alkyl side-chains attached to electron-poor heterocycies whilst leaving the ring intact this is not generally trne of electron-rich, five-membered systems. 

Acrylic-styrene-acrylonitrile terpolymers, ASA, are produced by simultaneous polymerization of styrene and acrylonitrile monomers in the presence of an acrylic rubber (polybutylacrylate). Thus, the material has a two-phase strucmre similar to ABS. However the elastomer phase in ASA is saturated and thus significantly more resistant to oxidative degradation. ASA is used in applications requiring good weatherability, mostly with PVC. The blends are primarily extruded for exterior trims and window profiles applications. 

Low resistance to oxidative degradation (Asadauskas et al., 1996, 1997, 2000) and poor low-temperature behavior (Erhan Asadauskas, 2000 Hagemann Roth-fus, 1988 Rhee, 1996) remain the major impediments to using soybean oil as a base stock in biobased lubricants. Soybean oil is the most widely available and least expen-... 

Meadowfoam is composed of unique long-ehain fatty aeids with 5-eieosenoie acid (62%) as the major fatty aeid. The other main eomponents are 5,13-doeosa-dienoic acid (19%), 5-docosenoic acid (3%) and 13-docosenoic acid (10%). The A5 unsaturation provides an excellent chemical moiety for synthetic modifications to the oil or fatty acids by providing a site at which a carboxylate stabilized carbocation can form. In addition, the A5 unsaturation has enhanced resistance to oxidative degradation (8) as evidenced by the high OSI of the oil (246.9 h at 110°C) or its methyl ester (69.4 h at 90°C). 

Thermoplastic polymer with sir., toughness, and flexibilily resist. to oxidative degradation, electricity, acids, alkalis, oxidizers, halogens... 

Table 1 provides a general list of common elastomers that are resistant to oxidative degradation. (Source Handbook of Polymer Science and Technology Volume 2 - Performance Properties of Plastics and Elastomers, N. P. Cheremisinoff - editor, Marcel Dekker Inc., New York, 1989). 

Polyaryl sulfone consists mainly of phenyl and biphenyl groups linked by thermally stable ether and sulfone groups. It is distinguished from polysulfone polymers by the absence of aUphatic groups, which are subject to oxidative attack. This aromatic structure gives it excellent resistance to oxidative degradation and accounts for its retention of mechanical properties at high temperatures. 

Specify a thicker geomembrane to attain greater survivability and resistance to oxidative degradation. 

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