Curing agents, based

In this way, a range of polymerizable diepoxides or organophosphorus-containing curing agents based on phosphine oxide, phosphate, or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) have been prepared and evaluated (Fig. 9). 

Epoxide and curing agents based on phosphine oxide and phosphate... 

Phosphonium halides and alkylene phosphoranes Latent curing agents based on adducts of epoxy resin d... 

Several other types of curing agent based upon the aliphatic amine approach are also commonly used in epoxide formulations. Examples are the glycidyl adducts of the aliphatic amines, in which the aliphatic amine is partially reacted with an epoxide to give an adduct with low volatility. Similar types of adduct can also be made by reacting the amines with ethylene and propylene oxides. By forming such adducts, reaction rates can be increased, but the physical properties may deteriorate somewhat, and, in the case of the ethylene and propylene oxide adducts, the compounds are hygroscopic. 

Another group of curing agents based upon the polyamine concept is the cycloaliphatic amines. These have properties somewhere between those of the aliphatic amines and the aromatic amines. Typical examples are aminoethyl piperazine and methane diamine... 

In other areas, POD has been used to improve the wear resistance of a mbber latex binder by incorporation of 25% of Oksalon fibers. Heat-resistant laminate films, made by coating a polyester film with POD, have been used as electrical insulators and show good resistance to abrasion and are capable of 126% elongation. In some instances, thin sheets of PODs have been used as mold release agents. For this appHcation a resin is placed between the two sheets of POD, which is then pressed in a mold, and the sheets simply peel off from the object and mold after the resin has cured. POD-based membranes exhibit salt rejection properties and hence find potential as reverse osmosis membranes in the purification of seawater. PODs have also been used in the manufacturing of electrophotographic plates as binders between the toner and plate. These improved binders produce sharper images than were possible before. 

Formulation. Polysulftde-based sealants are formulated with appropriate ingredients to obtain the desired properties for a particular appHcation. A typical formulation contains Hquid polysulftde polymer, curing agent, cure accelerators (bases) or retarders (acids), fillers, plasticizers, thixotropes, and adhesion promoters. 

The polyester resins used in this technology are typically based on terephthaUc acid [100-21 -0] CgH O, or isophthaUc acid [121 -91 -5] CgH O, neopentyl glycol [126-30-7] branched using trimellitic anhydride (38). The most commonly used curing agents are adducts of isophorone... 

Curing. Carboxyl cure sites are incorporated in the ethylene—acryhc terpolymer to permit cross-linking with primary diamines (1,7). Guanidines are added to accelerate the cure. Peroxides may also be used as curing agents in the terpolymer, but generally give inferior properties to vulcanizates based on diamine systems (8). Dipolymers are cured only with peroxides. 

Catalytic curing agents initiate resin homopolymerization, either cationic or anionic, as a consequence of using a Lewis acid or base in the curing process. The Lewis acid catalysts frequently employed are complexes of boron trifluoride with amines or ethers. 

The polyester alkyd moulding compositions are also based on a resin similar to those used for laminating. They are prepared by blending the resin with cellulose pulp, mineral filler, lubricants, pigments and peroxide curing agents on... 

Some rubber base adhesives need vulcanization to produce adequate ultimate strength. The adhesion is mainly due to chemical interactions at the interface. Other rubber base adhesives (contact adhesives) do not necessarily need vulcanization but rather adequate formulation to produce adhesive joints, mainly with porous substrates. In this case, the mechanism of diffusion dominates their adhesion properties. Consequently, the properties of the elastomeric adhesives depend on both the variety of intrinsic properties in natural and synthetic elastomers, and the modifying additives which may be incorporated into the adhesive formulation (tackifiers, reinforcing resins, fillers, plasticizers, curing agents, etc.). 

Aliphatic polyamines, amine adducts and polyamides react with epoxide resins at normal temperatures to give complexes with outstanding chemical resistance. Paints based on this type of reaction must be supplied in two separate containers, one containing the epoxide resin and the other the curing agent , the two being mixed in prescribed proportions immediately before use. 

When the epoxide is to be used, a basic curing agent such as a tertiary amine, R3N, is added to cause the individual prepolymer chains to link together. This "cross-linking" of chains is simply a base-catalyzed epoxide... 

A cement slurry additive consisting of methylcellulose, melamine-formaldehyde resin, and trioxane has been proposed for better bonding of cement to the casing string [20]. Bisphenol-A epoxide resins, with amine-based curing agents, sand filler, and a mixture of n-butanol and dimethyl benzene as a diluent, have been proposed as additives to increase adhesion properties of cement [572]. 

Catalytic cracking unit, 24 258-259 Catalytic curing agents, 10 388, 411-415 Lewis acids, 10 413 Lewis bases, 10 411-413 photoinitiated, 10 414-415 Catalytic cycle(s), 5 201... 

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