Epoxy oligomers

Foamed polymers based on mixtures of resol phenolic and carbamide oligomers resol and novolac oligomers epoxy and novolac pherrolic oligomers have been produced industrially in the USSR for several years 2). 

The condensation reaction of tetraethoxypolyphenykilsesqui-oxane with the excess of epichlorohydrin in the presence of catalysts Fe (III) and A1 chloride has been investigated and corresponding tetra epoxy-derivatives has been obtained. By polymerization reaction of tetraepoxypol5q)henylsilsesquioxanes with phenol-formaldehyde novolac oligomers epoxy-siliconorganic and phenol-formaldehyde novolac block-copolymers have been obtained. 

Products Acrylate monomers, acrylic acrylates, acrylate oligomers, epoxy acrylates, polyester acrylates, urethane acrylates, specialty acrylates, polyols/glycols, additives, photoinitiators/sensitizers... 

GPC is used for polymer profiling, i.e., when MWD is not required - examples are production quality control, checking lot-to-lot variations, and analysis of competitors products. The technique has been applied to numerous polymers and resins, and to oligomers, e.g., tetrahydrofuran (THF) solutions of a mixture of PS oligomers, epoxy resins, or mixed dimethyl formamide tetrahydrofuran solutions of styrene butadiene latex. 

As a rule, silanes are introduced 10 parts by weight of epoxy resin. At room temperature, polysulfide oligomer-epoxy resin mixtures solidify slowly this fact demands addition of activating agents. In this case, activating agents of the aminic type (ethylenediamine, dimethylurea, urotropine, polyalkylenepolyamine, amino-phenols, and phenols) are applied (871. 

Curing of polysulfide oligomer-epoxy resin mixtures with MnOj implies partial binding by chemical links of the resin. 

The nonbonded part can be chemically extracted with organic solvents. The viscosity of polysulfide oligomer-epoxy resin mixtures are modified during preservation. This phenomenon results from the interaction of —OH groups with the epoxy resins. 

TetrabromobisphenolA. TBBPA is the largest volume reactive flame retardant. Its primary use is in epoxy resins (see Epoxyresins) where it is reacted with the bis-glycidyl ether of bisphenol A to produce an epoxy resin having 20—25% bromine. This brominated resin is typically sold as a 80% solution in a solvent. TBBPA is also used in the production of epoxy oligomers which are used as additive flame retardants. 

Brominated Phenols. Tribromophenol [75-80-9] and dibromophenol [615-58-7] are both prepared through bromination of phenol. These are not actually used as reactive flame retardants, but rather as starting materials for other flame retardants such as BTBPE [37853-59-1] and epoxy oligomers. 

A second type of uv curing chemistry is used, employing cationic curing as opposed to free-radical polymerization. This technology uses vinyl ethers and epoxy resins for the oligomers, reactive resins, and monomers. The initiators form Lewis acids upon absorption of the uv energy and the acid causes cationic polymerization. Although this chemistry has improved adhesion and flexibility and offers lower viscosity compared to the typical acrylate system, the cationic chemistry is very sensitive to humidity conditions and amine contamination. Both chemistries are used commercially. 

As the length and frequency of branches increase, they may ultimately reach from chain to chain. If all the chains are coimected together, a cross-linked or network polymer is formed. Cross-links may be built in during the polymerisation reaction by incorporation of sufficient tri- or higher functional monomers, or may be created chemically or by radiation between previously formed linear or branched molecules (curing or vulcanisation). Eor example, a Hquid epoxy (Table 1) oligomer (low molecular weight polymer) with a 6-8 is cured to a cross-linked soHd by reaction of the hydroxyl and... 

The use of elastomeric modifiers for toughening thermoset resias generally results ia lowering the glass transition temperature, modulus, and strength of the modified system. More recendy, ductile engineering thermoplastics and functional thermoplastic oligomers have been used as modifiers for epoxy matrix resias and other thermosets (12). 

In the narrow sense, bis-maleimide resin means the thermosetting resin eom-posed of the bis-maleimide of methylene dianiline (BMI, bis(4-maleimidophenyl)-methane) and methylene dianiline (MDA, bis(4-aminophenyl)methane) (Fig. 1). Beeause of the addition meehanism, the resin is eured without elimination, whieh is a eharacteristic of this resin. Bis-maleimide resin is used as a thermally stable matrix up to 204°C (400 F) whieh typical epoxy resins may not normally be used. However, in spite of having an imide structure, bis-maleimides are classified as being moderately thermally stable resins. The aliphatic structure of the resin is not stable for long periods above 232°C (450°F.) If a highly aromatic thermally stable thermosetting resin is necessary, acetylene end-capped aromatic imide-based oligomers should be used. 

Of the commercially available EB-curable adhesives [9-12], the resins fall within one of two categories based on their curing mechanisms. The majority of EB-curable resins are based on (meth)acrylate-functionalized oligomers involving a free-radical curing mechanism. The second category is the epoxy resins that cure by a cationic mechanism. 

The epoxy toluene oligomer was also obtained by alkylation of toluene with PEC as shown in Scheme (10). 

The structure of the products were characterized by two detector gel-chromatography (recractometer and UV). The direction of the alkylation reaction of toluene with EC was changed depending on the reaction condition as follows if the ratio of toluene-EC is 1 5 mol, the alkylation reaction is toward obtaining the PEC at 273 K and if the ratio is reverse at 333 K, the reaction undergone to obtain epoxy toluene oligomer is shown in Fig. 1. 

Unsaturated acrylic oligomers are made from unsaturated acrylic monomers. For example, an epoxy acrylate may be made by reaction of acrylic acid with epoxy resin. 

Rozengerk,v. A. Linetics, Thermodynamics and Mechanism of Reactions of Epoxy Oligomers with Amines. Vol. 75, pp. 113 — 166. 

Void-free phenolic networks can be prepared by crosslinking novolacs with epoxies instead of HMTA. A variety of difunctional and multifunctional epoxy reagents can be used to generate networks with excellent dielectric properties.2 One example of epoxy reagents used in diis manner is the epoxidized novolac (Fig. 7.34) derived from the reaction of novolac oligomers with an excess of epichlorohydrin. 

Phenolic networks, 411 Phenolic-novolac-cured systems, 415 Phenolic novolac-epoxy networks, flame retardance of, 415 Phenolic oligomers, 375... 

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