Epoxides phenolates

Epoxidized phenol novolak and cresol novolak are the most common curing agents. The composition of the resin and hardener system is optimized for each specific appHcation eg, incorporating phenol novolaks in the matrix resin can iacrease cure speed. 

Laminates have been prepared for the manufacture of chemical plant. They have better heat and chemical resistance than the polyester- epoxide- phenolic- or aminoplastic-based laminates but because of the low viscosity of the resins were not easy to handle. Because they were also somewhat brittle, furan-based laminates have been limited in their applications. 

Virtually all organisms possess biotransformation or detoxification enzymes that convert lipophilic xenobiotics to water-soluble and excretable metabolites (Yu et al. 1995). In the metabolic process, PAHs are altered by Phase I metabolism into various products such as epoxides, phenols,... 

Syntactic foams manufactured from hollow glass or silica microspheres and an epoxide, phenolic or other matrix resin represent a class of lightweight structural materials used for buoyancy purposes, insulation and packaging. The effect of silanes on the mechanical properties of syntactic foams at a nominal density of 0.35 g/cm3 is shown in Tables 14-16. The Proportional Limit is defined as the greatest stress which the foam is capable of sustaining without any deviation from proportionality of stress to strain (Hooke s Law). 

The purpose of this paper is to present a technique whereby manufacturing process dynamics for structural polymers can be accurately defined through efficient laboratory rheological characterization. Structural polymers, in this paper, refer principally to the thermosetting epoxides, phenolics and polyimides. This type of test pattern, however, is generally applicable to the production and utilization of most polymers. The engineering applications associated with these polymers involves primary and secondary aerospace articles. In this situation, failure to meet performance criteria could result in catastrophic loss of the vehicle and associated cargo. 

Seryakov, G. V., Sokolov, G. M., Voskresensky, V. A. Casting epoxide-phenolic foam. 

Animals encounter poison in the plants they eat, from other animals that use poisons in attack and for protection, and from toxin-producing bacteria and fungi. Animals are exposed to toxic metals released from minerals, and even the oxygen that all animals depend on is a very poisonous gas. Leakage of mineral oil, with many toxic and lipohilic substances, is also an old challenge that organisms had to adapt to. Substances produced inside the animal (e.g., ammonia, epoxides, phenolic substances) may also be toxic. Animals must therefore have many protection mechanisms against toxic substances in order to survive and reproduce. 

The polycyclic aromatic hydrocarbons (PAH) are common environmental pollutants that have been implicated as etiological factors in human chemical carcinogenesis (13, 14). One such PAH that has been studied extensively is benzo[a]-pyrene (G3). The metabolic activation of this compound to various reactive intermediates, including epoxides, phenols, and quinones, is performed by the cytochrome-P450-containing mixed function oxidase (MFO) system. Subsequent metabolic steps may involve the hydration of epoxides to dihydrodiols, mediated... 

Shechter and Wynstra ( ) proposed two possible types of reactions between phenol and a glycidyl ether. One involves direct reaction of the phenol with the epoxide the other involves direct reaction of the aliphatic hydroxyl, generated from the epoxide-phenol reaction, with another epoxide as shown in Reactions 22 and 23 ... 

Using model systems, they found that without a catalyst no reaction occurred at 100 °C. At 200 °C epoxide disappeared at a much faster rate than phenol did (Figure 5) about 60% of the reaction was epoxide-phenol and the other 40% was epoxide-formed alcohol. Because alcohol was absent at the beginning of the reaction and only appeared when phenol reacted with epoxide, it was concluded that the phenol preferred to catalyze the epoxide-alcohol reaction rather than react itself. 

Dr. Fred Guengerich at Vanderbilt University has published mechanistic schemata for cytochrome P450 involvement in an extensive array of both common and uncommon oxidative reactions and reductive reactions. Some of those are exhibited later in this chapter in a brief consideration of reductive reactions. Mechanisms for carbon hydroxylation, heteroatom oxygenation, N-dealkylation, O-dealkylation, alcohol oxidation, arene epoxidation, phenol formation, oxidation of olefins and acetylenes, reduction of nitro compounds, reductive dehalogenation, and azo reduction, to name a few, are provided. 

The basic catalysis of the epoxide-phenol reaction has been studied by a variety of authors (12,13). In general, the conclusion has been that basic catalysis gives selectivity for the phenol-epoxide reaction over the secondary alcohol-epoxide reaction (the secondary alcohol being formed from the opening of an epoxide). Although the base catalyzed reaction has been studied, the specific mechanism for triphenylphosphine Catalysis has not been determined. We propose the mechanism shown in Reaction Scheme 3 which is consistent with our experimental results. 

TaBTe III illustrates how important it is in practice to choose highly selective catalysts for the polyaddition reaction. With a strong base like TBAH as catalyst very little branching is observed at 100°C. At 150°C, however, k2 is over a 100 times larger than at 100°C. Although this would normally have led to extensive branching, because of a nearly thirtyfold increase in the rate constant, k], for the epoxide/phenolic OH reaction branching is not very extensive. 

Synthetic thermosets which cure on heating to solids, e.g., amino plastics, epoxides, phenolic resins, unsaturated polyesters, polyaromatics, and furanes. 

Both academic and industrial research and development, as well as cooperation between industries, has resulted in a large effort in the discovery, synthesis, and catalytic application of framework metal-containing zeotype materials. These collaborations have led to new appHcations of metal-containing zeotype materials for the large-scale production of chemicals without major by-product formation. New environmentally friendly processes such as propylene epoxidation, phenol hydroxylation, ammoximation of cyclohexanone, and aromatization of light paraffins have been commer-ciahzed. Many new developments are in the pipehne, and they will Hkely be commerciahzed when both the economics and the environmental requirements become favorable. 

Next to the limited analytical information available from studies of PAH-metabolism, there is a surprising lack in the current literature of research data on analytical methods for polar PAH-derivatives in environmental samples, e.g. epoxides, phenols, nitroarenes, which may be of great toxicological significance. 

There are many examples in the literature of the structural characterization of polymeric systems by FD-MS. Some of these will be briefly mentioned here. Saito and coworkers in Japan have studied a number of polymers by FD-MS. FD spectra were used to identify various poly(ethylene glycol) and poly(pro-pylene glycol) initiators (water, ethyleneimine, glycerol, sorbitol, sucrose). Structures of bisphenol A-based epoxy resins were elucidated. The degree of methylation in methylol melamine resins was assessed. Various novalak resins (made from phenol, alkylphenols, and epoxidized phenols) were characterized. Styrene polymerized with various initiators and chain transfer agents was studied in some cases deuterium labeling was used to help... 

Other thermoset resins such as epoxides, phenolics and polyurethanes are also used in reinforced form, as are some thermoplastic polymers. Many need to be protected by surface coatings if retention of properties after extended weathering is important. 

Metabolites identified or investigated Epoxides Phenols Diols Quinones Conjugates... 

The monomer is obtained by reacting bisphenol A with epichlorohydrin. Compounds with q = 0.1-0.6 are liquids, those with q = 2-12 are solids. Other epoxide resins are based on epoxidized phenol/formaldehyde and cresol/formaldehyde resins, or on cycloaliphatic or heterocyclic structures. Commercially available epoxide resins are generally compounded, that is, they also contain plasticizers, diluents, pigments, etc. 

Primary and secondary aircraft stmctures Toughened epoxides Phenolic/poly(vinyl formal)... 

However, the introduction of stabilizers is essential, since processes of thermal and thermooxidative destruction develop extremely intensively during the use and reprocessing of such polymers, leading to a sharp deterioration of their physicomechanical and dielectric properties. Thus, an extremely urgent problem at the present time is a detailed investigation of the processes of decomposition of condensation polymers for developing a theory of their stabilization. Works in the field of the study of the thermal and thermooxidative destruction of certain condensation polymers (epoxide, phenol-formaldehyde resins, polycarbonate, and polyarylates) are outlined below. 

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