Prepolymers, bisphenol

High molar mass epoxy prepolymers containing rabber dispersions based on carboxyl-terminated butadiene-acrylonitrile copolymer were prepared from initially miscible solution of low molar mass epoxy prepolymers, bisphenol A and carboxyl-terminated NBR. During chain extension inside a twin screw extruder due to epoxy-phenoxy and epoxy-carboxy reactions, a phase separation process occurs. Epoxy-phenoxy and epoxy-carboxy reactions were catalysed by triphenylphosphine. The effect of reaction parameters (temperature, catalyst, reactant stoichiometry) on the reactive extrasion process were analysed. The structure of the prepolymers showed low branching reactions (2-5%). Low molar mass prepolymers had a Newtonian rheological behaviour. Cloud-point temperatures of different reactive liquid butadiene aciylonitrile random copolymer/epoxy resin blends were measured for different rubber concentrations. Rubber... 

Epoxy adhesives are prepared in two steps. S -2 reaction of the disodium salt of bisphenol A with cpichlorohydrin forms a "prepolymer," which is then "cured" by treatment with a triaminc such as I-I2NCH2CH2NHCH2CH2NEI2-... 

Acetylene-terminated resins (ATR) bisphenol-based, synthesis, 17-29 thermally curable, 6 Acetylene-terminated sulfone (ATS), thermally curable, 5 Acid values, castor oil prepolymer formation, 241 Addition polymerization... 

A soluble prepolymer results from the addition of bismaleimidodiphenyl methane 1 to diallyl bisphenol A 2 at approximately 150 °C. In the present study, a detailed 13C NMR investigation has provided strong evidence for the proposed structure of the soluble olig< ier. The NMR has also provided s< >e idea of the rate of... 

Fumaric and itaconic acids are also used as the diacid component. Most reaction formulations involve a mixture of a saturated diacid (iso- and terephthalic, adipic) with the unsaturated diacid or anhydride in appropriate proportions to control the density of crosslinking (which depends on the carbon-carbon double-bond content of the prepolymer) for specific applications [Parker and Peffer, 1977 Selley, 1988], Propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and bisphenol A are also used in place of ethylene glycol as the diol component. Aromatic reactants are used in the formulation to improve the hardness, rigidity, and heat resistance of the crosslinked product. Halogenated reactants are used to impart flame resistance. 

The reaction actually involves the sodium salt of bisphenol A since polymerization is carried out in the presence of an equivalent of sodium hydroxide. Reaction temperatures are in the range 50-95°C. Side reactions (hydrolysis of epichlorohydrin, reaction of epichlorohydrin with hydroxyl groups of polymer or impurities) as well as the stoichiometric ratio need to be controlled to produce a prepolymer with two epoxide end groups. Either liquid or solid prepolymers are produced by control of molecular weight typical values of n are less than 1 for liquid prepolymers and in the range 2-30 for solid prepolymers. 

Epichlorohydrin is reacted with a variety of hydroxy, carboxy, and amino compounds to form monomers with two or more epoxide groups, and these monomers are then used in the reaction with bisphenol A [Lohse, 1987]. Examples are the diglycidyl derivative of cyclohex-ane-l,2-dicarboxylic acid, the triglycidyl derivatives of p-aminophenol and cyanuric acid, and the polyglycidyl derivative of phenolic prepolymers. Epoxidized diolefins are also employed (Sec. 9-8). 

To demonstrate the UV crosslinkability of the polymers formed having pendant acyloxyimino groups, copolymers of bisphenol diacrylate and 1,6 hexanediol diacrylate were prepared by thermal methods with 5% (by weight) of pyrene oxime acrylate and phenanthrene oxime acrylate, both of which have considerable absorption in the region of 320-360 nm. The polymerization was stopped before the gel point and the prepolymer solutions were then irradiated with light from a monochromator at the maximum of... 

The formation of a prepolymer involves two different kinds of reactions. One is an SN2-type displacement, and the other is oxide-ring opening of the product by attack of more bisphenol A. Usually, for practical purposes the degree of polymerization n of the prepolymer is small (5 to 12 units). 

D isphenol-A carbonate oligomers have been used in the syntheses of random and block copolycarbonates (J, 2). The physical properties of these polymers can be altered by tailoring sequence distribution and block size in the copolymer. To tailor sequence distribution and block size, it is necessary to know the molecular weight and molecular-weight distribution of bisphenol-A prepolymers present during synthesis. 

For a series of epoxy phenolic novolac prepolymers cured with bisphenol A, imidazole, or DDS and toughened with 10 per CSR particles, the crosslink density was varied over a wide range of Me from 200 g mol 1 up to 2000 gmoF1 (Lu, 1995). In this series an increase in Me is related to a decrease in... 

Komiya et al. [13] recently introduced the novel, environmentally friendly process from Asahi Chemical Industry Co. for the production of polycarbonates, which requires neither phosgene nor solvent (Scheme 1). In this process bisphenol A undergoes a prepolymerization with diphenyl carbonate in the melt. A simple crystallization of the prepolymer is fol-... 

As an additional component, various thermoplastic polymers can be used. As a binder for copper clad laminates, a solution of solid epoxide resin (Epikote 1001), BPA/DC prepolymer, Zn acetate and poly(phenylene sulfide) was used [83], Other binders for reinforced plastics contain polysulfone. Such compositions consist of liquid BPA/ECH epoxide resin, BPA/DC prepolymer, polysulfone and bis(4-hydro-xyphenyl)sulfone [85]. Bis(4-aminophenyl)sulfone can be also added [86]. In such systems the bisphenol reacts with the epoxide resin as a chain extension agent, whereas the diamine crosslinks the diepoxide. The Tg values are close to 200 °C. They can be increased a little, if the BPA/ECH epoxide resin is replaced by the tetra-epoxide A,A,A, A -tetrakis(2,3-epoxypropyl)diaminodiphenylmethane [87]. 

Fire resistant polymers were obtained from brominated epoxynovolak resin, BPA/DC prepolymer, BMI, Zn acetate and benzoyl peroxide [103] or from an oligo-aspartimide (BMI-diamine reaction product), BPA/DC, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane (i.e. Tetrabromo-Bisphenol A) and 2-ethyl-4-methylimi-dazole [104]. A mixture of BPA/DC, BMI and epoxide resin with brominated polycarbonate, copoly[oxy-2,6-dimethylphenylene)-(oxy-2,3,6-trimethylphenylene)] and a catalyst was also suggested [105],... 

The most common epoxy resins use a prepolymer made from bisphenol A and epichlorohydrin. 

With exactly equal amounts of bisphenol A and epichlorohydrin, this polymerization would continue until the polymer chains were very long and the material would be a solid polymer. In making epoxy resins, however, excess epichlorohydrin is added to form short chains with epichlorohydrins on both ends. More epichlorohydrin gives shorter chains and a runny prepolymer. Less epichlorohydrin gives longer chains (containing up to 25 epichlorohydrin/bisphenol A units) and a more viscous prepolymer. 

Sometimes the system is formulated so that multiple cure mechanisms are possible and can occur sequentially or simultaneously. Compositions that rely on both epoxy and urethane chemistry are examples.62,94,95 These are compositions containing the diglycidyl ether of bisphenol A, an isocyanate or isocyanate-terminated prepolymer, amines or other reactants for either epoxy or isocyanates, and catalysts. 

The unreacted terminal epoxide groups can react with other diamine molecules to form a rigid network polymer. In this reaction the functionality of the bisphenol A-epichlorohydrin prepolymer 1-20 will be 2 since hydroxyl groups are not involved and the functionality of each epoxide group is one. 

When bisphenol A is treated with excess epichlorohydrin, this stepwise process continues until all the phenolic OH groups have been used in ring-opening reactions, leaving epoxy groups on both ends of the polymer chains. This constitutes the fluid prepolymer, as shown in Figure 30.6. 

The polyadipates of tetrachloro bisphenol-A depicted below, containing small amounts of HPPO, are similarly used [154] as prepolymers to give, upon UV irradiation, macroradicals able to initiate the polymerization of styrene and produce block copolymers. 

The prepolymer stage in most cases is DGEBA (diglycidyl ether bisphenol A) (see Fig. 15.2a). 

Epoxy Prepolymers. These prepolymers are commonly formed from Bisphenol A and epichlorhydrin (Figure 4). A variety of other materials are also employed, but to a lesser extent. The lowest member of the series might well be considered structoterminal, while all the others must be considered as structopendant prepolymers. Molecular weights range from a few hundred to about 4000 for commonly used industrial epoxy prepolymers. Most common cross-linking agents are amines and anhydrides however, epoxies may also be combined with a variety of other prepolymer systems (25). 

The most widely used epoxy resins and adhesives are based on a prepolymer made from bisphenol A and epichlorohydrin. On treatment with base under carefully controlled conditions, bisphenol A is converted into its anion, which acts as a nucleophile in an S142 reaction with epichlorohydrin. Each epichlorohydrin molecule can react with two molecules of bisphenol A, once by S 2 displacement of chloride ion and once by opening of the epoxide ring. At the same time, each bisphenol A molecule can react with two epichlorohydrins, leading to a long polymer chain. Each end of a prepolymer chain has an unreacted epoxy group, and each chain has numerous secondary alcohol groups. 

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