Condensation Resins

Alternatively, thermal cracking of acetals or metal-catalyzed transvinylation can be employed. Vinyl acetate or MVE can be employed for transvinylation and several references illustrate the preparation especially of higher vinyl ethers by such laboratory techniques. Special catalysts and conditions are required for the synthesis of the phenol vinyl ethers to avoid resinous condensation products (6,7). Direct reaction of ethylene with alcohols has also been investigated (8). 

Resorcinol differs from other phenols in that it reacts readily with formaldehyde under neutral conditions at ambient temperature. To make stable adhesives, which can be cured at the point of use, they are prepared with less than a stoichiometric amount of formaldehyde. About two thirds of a mole of formaldehyde for each mole of resorcinol will give a stable resinous condensation product. The resin is formed into a liquid of convenient solids content and viscosity. Such solutions have infinite stability when stored in closed containers. Glue mixes formed at the point of use from these solutions, on addition of paraformaldehyde-containing hardeners, will have a useful life of several hours due to two principal factors (1) the paraformaldehyde depolymerizes to supply monomeric formaldehyde at a slow rate, as determined by the pH (2) the availability of the formaldehyde is also controlled by the kind and amount of alcohol in the solvent. Formaldehyde reacts with the alcohol to form a hemiacetal. This reaction is reversible and forms an equilibrium which exerts further control on the availability of the formaldehyde. 

The application of ultrasound in solid-phase synthesis has been shown to be useful in several cases such as carboxylic acid attachment to Merrifield resin,condensation... 

This product is a resinous condensation designed to provide flame retardancy to nylon. The application requires curing, certain water repellents may be incorporated into some finishes-contains formaldehyde. 

Use Stabilizer for polyvinyl chloride resins, condensation catalyst. 

Use Organic synthesis, preparation of resinous condensation products. 

Alcohol resins, polyvinyl Alkyd resins Allyl resins Butadiene copolymers, containing less than 50 percent butadione Carbohydrate plastics Casein plastics Cellulose nitrate resins Cellulose propionate (plastics) Coal tar resins Condensation plastics Coumarone-iodene resins Cresol resins Cresol-furfural resins Dicyandiamine resins Diisocyanate resins Elastomers, nonvulcanizable (plastics)... 

Eccogard. [Eastern Color Chem.] Resinous condensate providing flame letardancy to nylon. 

Fixogene. pCISorf.UIQ Dicyandiamide formalddiyde resinous condensate fixing agent for d on ceQulosic fibers. 

Inset [Hart Prods. Corp.] Resin condensate fixative fat direct dyes. 

FIxanoL [ICIAm.] Resinous condensate fixative for direct and reactive dyes. 

Treating the fibre with resin, condensates, or crosslinking agents ... 

Polyimides can be prepared as either thermoplastic or thermoset resins. There are two types of polyimides, condensation, and addition resins. Condensation polyimides are available as either thermosets or thermoplastics. The additional polyimides are available only as thermosets. 

Precaution Combustible Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of Sn Uses Heat stabilizer and lubricant for PVC resins condensation catalyst plasticizer Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, Atofina... 

Xylene-formaldehyde resins condensed with 4,4 -isopropylidene-diphenol-epichlorohy-drin epoxy resins substances identified in Sec. 175.300... 

Bisphenol A and F n. Dihydroxydiphenyldi-methylmethane, mol wt 224.1. Insoluble in water. Used in the manufacture of phenolic and epoxy resins. Condensation product formed by reaction of two (bis) molecules of phenol with acetone. This polyhydric phenol is a standard resin intermediate, along with epichlorohydrin, in the production of epoxy resins (See image). 

When zinc is introduced into the BWR reactor water, one of its primary removal mechanisms is adsorption by the iron-based corrosion products deposited on the fuel rods. It is this incorporation and subsequent release which gives rise to the buildup of an inventory of radioactive Zn (see below). It is important, therefore, to minimize the input of iron to the reactor water so that the inventory of Zn generated is also minimized. As was mentioned above, the natural zinc plants are all equipped with a powdered resin condensate treatment system and, thus, show low iron input to the reactor water. Based on this experience, the goal for iron input in the case of zinc addition is a feedwater total iron concentration of less than 2 ppb. 

Since the cured resins are infusible and insoluble in most solvents, little progress was made initially in determining structural features. It was only after analysis of the uncured resinous condensation products was attempted that some progress was realized in elucidating the structures of these resin systems. The research of Baekeland and Bender involved the synthesis of phenolic resins from various substituted phenols and the application of different condensation methods. ... 

The resinous condensation products produced according to this method represent a mixture of polyallqrlenealkylphenols, from which it is very difficult to isolate the dialkylenetriallg lphenols. 

PL 5 pM gel mixed D 200 - 0.4 X 10 Resins, condensation polymers Polystyrene standard separation, resins, epoxy resin, polybutadiene, polysiloxane, polycarbonate... 

Benzoguanamine closely resembles melamine in that reaction with formaldehyde gives methylol derivatives and then resinous condensates. Butylated... 

Thiourea closely resembles urea in that reaction with formaldehyde gives methylol derivatives and then resinous condensates which on continued heating yield network structures. Thiourea-formaldehyde resins are slower curing than urea-formaldehyde resins and the hardened products are more brittle and more water-resistant. At one time thiourea-formaldehyde resins were added to urea-formaldehyde resins to give mouldings and laminates with improved water-resistance. These mixed resins have now been largely superseded by melamine-formaldehyde resins which give products with better resistance to heat. 

The RFL adhesive dip is prepared by dissolving the resorcinol in water, adding the formaldehyde and then the alkali as condensation catalyst, to produce the aqueous solution of the resin condensate. This generally takes place at room temperature in about 6 hours. 

---