Epoxy resins oxidation reactions

High purity 4-dodecylphenol is used to produce specialty surfactants by its reaction with ethylene oxide. The low color of high purity 4-dodecylphenol is important in this appHcation from a standpoint of aesthetics. 4-Dodecylphenol is also used to produce phenoHc resins which are used in adhesive appHcations and printing inks. 4-Dodecylphenol is also used as an epoxy curing catalyst where the addition of 4-dodecylphenol accelerates curing of the epoxy resin to a hard, nontacky soHd. 

Isopropa.nola.mines. Reaction of propylene oxide with ammonia yields mono-, di-, and triisopropanolamines. These products find use as soluble oils and solvents, emulsifiers, waterless hand cleaners, cosmetics, cleaners, and detergents. In industrial apphcations isopropanolamines are used in adhesives, agricultural products, corrosion inhibitors, coatings, epoxy resins, metalworking, and others (51). 

Epoxy ester Epoxy esters are a type of alkyd where a high molecular weight resin is reacted with alkyd resin. The curing mechanism remains primarily through the oil-oxidation reaction and their properties are in no way similar to the chemically reacted epoxies. They have similar properties to alkyds although with improved chemical resistance but inferior appearance. They form a reasonably hard, oil-resistant coating, which can sometimes be suitable for machinery enamels, but are primarily for interior use, since they tend to chalk rapidly on exteriors. Their best use is for chemical or water resistance where circumstances dictate that finishes that are more superior cannot be used. 

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

Fine chemicals These are produced in small volumes and purchased on the basis of chemical composition, purity and price. Examples are chloropropylene oxide (used for the manufacture of epoxy resins, ion-exchange resins and other products), dimethyl formamide (used, for example, as a solvent, reaction medium and intermediate in the manufacture of pharmaceuticals), n-butyric acid (used in beverages, flavorings, fragrances and other products) and barium titanate powder (used for the manufacture of electronic capacitors). 

While freshly cleaved surfaces clearly contain some steps and other defects, the surfaces are remarkably stable to corrosion. Dramatic evidence of the stability of MoSe2 surfaces was provided by Stickney et al. who obtained LEED and Auger spectra of surfaces that had been exposed to the atmosphere and a variety of oxidizing solutions (35). Except for the presence of a ubiquitous carbon which was attributed to the epoxy resin or cleaving tape, no evidence for surface reactions was found. Long term stability tests of a photoelectrochemical cell made with a WSe2 electrode, where over 400,000 coulombs/cm2 were passed through the cell with no detectable photocorrosion, also attest to the durability of these surfaces (36). 

Other possible reactions, such as homopolymerization (epoxide+epoxide) and epox-ide+hydroxyl group (in the latter stages of cure), can be neglected when the ratio of epoxide to amine is stoichiometric and in the absence of catalyst or accelerator [194], For TGDDM/DDS resins, the homopolymerization reaction may be neglected at cure temperature below 180°C [84], At temperatures between 177°C and 300°C, dehydration and/or network oxidation occur, which results in formation of ether cross-linkings with loss of water. Decomposition of the epoxy-OH cure reaction can also take place, which results in propenal... 

The liquid polymer is converted to the rubbery state by reagents that react with mercaptan (-SH) and side groups of the polymer segments by oxidation, addition or condensation to effect sulfide (-S-S-) bond formation. The oxidation reactions are exothermic and accelerated by an alkaline environment. The most commonly employed oxidizing agents which are suitable for curing liquid polymers are cobalt or manganese or lead octoate, p-quinonedioxime and di- or tri-nitrobenzene. Epoxy resin also reacts with liquid polysulfide polymers by addition in the presence of an aliphatic or aromatic amine and polyamide activator as shown in Equation 5.8 ... 

Oxidation studies have been made for cured epoxy resins and the relative stability of the functional groups was established by following the changes in the absorbance ratios of bands associated with the particular functional group 231>. Hence the most unstable groups can be determined easily and their reactions separated from the more stable units. The irreversible 232) and reversible 2331 effects of moisture on epoxy resin systems have also been studied by FT-IR using the difference spectrum method 234). (Fig. 20) shows the interaction spectra obtained after three cycles of water sorption and redrying. The reversible nature of the interactions are clearly demonstrated. 

For the copolymerization of epoxides with cyclic anhydrides and curing of epoxy resins, Lewis bases such as tertiary amines are most frequently used as initiators. In this case, terminal epoxides react with cyclic anhydrides at equimolar ratios. The time dependence of the consumption of epoxide and anhydride is almost the same for curing 35-36> and for model copolymerizations 39,40,45). The reaction is specific 39,40) to at least 99 %. In contrast, the copolymerization with non-terminal epoxides does not exhibit this high specificity, probably because of steric hindrances. The copolymerization of vinylcyclohexene oxide or cyclohexene oxide is specific only to 75-80 % and internal epoxides such as alkylepoxy stearates react with anhydrides only to 60-65 %. On the other hand, in the reaction of epoxy resins with maleic anhydride the consumption of anhydride is faster 65the products are discoloured and the gel is formed at a low anhydride conversion 39). Fischer 39) assumes that the other resonance form of maleic anhydride is involved in the reaction according to Eq. (33). 

Wang, C. S. and Lin, C. H., (National Science Council, Taiwan), Epoxy resin rendered flame retardant by reaction with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, U.S. Patent, 2001 6 291 627. 

Glycidyl ethers of aliphatic polyols based on polyglycol, glycerin, and other polyols are flexible epoxy resins. They are used as reactive diluents and flexibihzers for solvent-free epoxy resin formulations. Epoxy-polyglycol resins that are produced from the reaction of epichlorohydrin and polyester polyols based on ethylene or propylene oxide are the most common of these types of flexible epoxy resins. Examples of typical commercial aliphatic epoxy resins are shown in App. C. 

The most important inference is that Chemisorption is a direct response to carboxyl group concentration indicated by the XPS photopeak component at 288.7 eV. It seems likely that weak add functionality is of minor import to applications for surface treatments, while interfacial phenomena such as practical adhesion may be sensitive to small concentrations of very high site energies. Interphase modification in epoxy resins, for example, can occur by direct reaction of epoxide groups with surface carboxyls (17), or by accelerated cure chemistry near the surface (39). Carboxyl groups on carbon surfaces may interact with basic moieties in polymers such as polycarbonate or poly(ethylene)oxide (40=42), or promote interfacial crystallinity that improves impact strength and other aspects of composite performance (43, M)-... 

Organic phosphorus compounds are also produced in the interaction of wliite phosphorus with an epoxide or an episulfide and an alcohol or mercaptane in the presence of alkaline catalysts at 25 °C to 200 °C In order to remove P-H bonds the reaction mixture is treated witli formaldehyde and oxidized. The products are said to be useful as hardeners for epoxy resins or as antistatic agents and fire retardants. 

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