Epoxies halogenated

Polyacrylic elastomer is a chemically saturated polymer of acrylic acid esters. Since esters are rather inert, other groups such as epoxy, halogen and carboxyl must be incorporated into the polymer to introduce sites for curing. We have studied the effect of various ammonium and phosphonium salt catalysts on the rate of crosslinking of polyacrylic elastomers which contain carboxyl and epoxy groups as cure-sites. We find that the catalytic activity of onium salts correlates with nucleophilicity of their anions. 

The binder system of a plastic encapsulant consists of an epoxy resin, a hardener or curing agent, and an accelerating catalyst system. The conversion of epoxies from the Hquid (thermoplastic) state to tough, hard, thermoset soHds is accompHshed by the addition of chemically active compounds known as curing agents. Flame retardants (qv), usually in the form of halogens, are added to the epoxy resin backbone because epoxy resins are inherently flammable. 

There have been other approaches to obtaining rubber/metal adhesion besides primers or additives consisting of phenolics or epoxies plus halogenated elastomers. For example, carboxylated polymers (olefins and diolefins copolymerized with acrylic acid monomers) have shown excellent adhesion to metals. Very little carboxyl is necessary, and polymers with carboxyl contents as low as 0.1% show good adhesion when laminated to bare steel. When these materials possess... 

Another potential route for the synthesis of organofunctionally terminated disiloxanes is the modification or transformation of preformed carbofunctional disiloxanes into others. For this purpose, disiloxanes with halogen, cyano and epoxy end... 

Double bonds having oxygen and halogen substituents are susceptible to epoxi-dation, and the reactive epoxides that are generated serve as intermediates in some useful synthetic transformations in which the substituent migrates to the other carbon of the original double bond. Vinyl chlorides furnish haloepoxides that can rearrange to a-haloketones. 

Principles and Characteristics Combustion analysis is used primarily to determine C, H, N, O, S, P, and halogens in a variety of organic and inorganic materials (gas, liquid or solid) at trace to per cent level, e.g. for the determination of organic-bound halogens in epoxy moulding resins, halogenated hydrocarbons, brominated resins, phosphorous in flame-retardant materials, etc. Sample quantities are dependent upon the concentration level of the analyte. A precise assay can usually be obtained with a few mg of material. Combustions are performed under controlled conditions, usually in the presence of catalysts. Oxidative combustions are most common. The element of interest is converted into a reaction product, which is then determined by techniques such as GC, IC, ion-selective electrode, titrime-try, or colorimetric measurement. Various combustion techniques are commonly used. 

Unsaturated groups are very interesting for application development because this specific functionality opens up a broad range of possibilities for further (chemical) modification of the polymer structure, and therefore its physical and material properties. The direct microbial incorporation of other functional substituents to the polymer side chains, e.g. epoxy-, hydroxy-, aromatic-, and halogen functional groups, influences the physical and material properties of poly(HAMCL) even further [28,33,35,39-41]. This features many possibilities to produce tailor-made polymers, depending on the essential material properties that are needed for the development of a specific application. 

AS A FLAME RETARDANT. The zinc borate is an efficient synergist of organic halogen sources. In certain halogen-containing systems such as unsaturated polyester, epoxy (3), and rigid PVC, the zinc borate alone can outperform antimony oxide as shown by the Oxygen Index and UL-94 tests (Fig. 3, 4, and 5). 

Treating ally lie and homoallylic epoxy alcohols with an equivalent amount of halogen (Br2, I2) in the presence of a stoichiometric amount of Ti(OPr )4 provides halohydrins under mild conditions with a high degree of generality and with good regioselectivity (Scheme 4-12).26... 

Other renewable resources sorbitol (I), cellobiose (XXV), etc. can be used in similar ways as starting materials in the preparation of epoxy resins. We are now working on a direct two-step preparation of diepoxy sorbitol derivatives by direct halogenation of the two primary hydroxyl groups with the formation of 1,6-dichloro-1,6-dideoxy-sorbitol, (XXIII), followed by epoxy ring formation (1,2 5,6-dianhydrosorbitol (XXIV) ... 

---