Epoxy resin Diglycidyl ether of bisphenol

Fig. 2.5 Epoxy resins, diglycidyl ether of bisphenol-A (DGEBA).

As an example for an epoxy resin, diglycidyl ether of bisphenol-A (Epon 828 by Yuka Shell Epoxy Co. Ltd.) was cured with 2-ethyl -4-methylimidazole or N,N-dimethylbenzylamine. The concentration of the curing agent was changed from 0.05 to 0.2 molar ratio. The curing temperature was changed from 40 C to 80 C. 

Figure 6.8 Variable-temperature MAS/CP/DD NMR spectra of an epoxy resin diglycidyl ether of bisphenol A (DGEBA) cured with piperidine. After [48].

Epoxy-zirconia nanohybrid materials were synthesized from bisphenol A epoxy resin (diglycidyl ether of bisphenol A), zirconium(IV)- -propoxide, and hexahydrophthalic anhydride using a combined sol-gel/polymerization process. The obtained materials exhibited nanosized zirconia particles uniformly dispersed within the epoxy matrix and, consequently, showed excellent optical transparency [183-185]. 

FIGURE 13.10 Typical DGEBA epoxy resin (diglycidyl ether of bisphenol A). The epoxy resins used in conservation are mixtures of short ohgomers with the average value of n < 1. Each molecule has two epoxy groups where cross-linking can take place (CAS no. 1675-54-3, n=0, MW 340). 

The microwave and thermal cure processes for the epoxy-amine systems (epoxy resin diglycidyl ether of bisphenol A, DGEBA) with 4,4 -diaminodiphenyl sulfone (DDS) and 4,4 -diaminodiphenyl methane (DDM) were investigated for 1 1 stoichiometries by using fiber-optic FT-NIR spectroscopy. The kinetic rate parameters for the consumption of amines were determined by a least squares curve fit to a model for epoxy/amine cure. The activation energies for the polymerization of the DGEB A/DDS system were determined for both cure processes and found to be 66 and 69 kJ/mol for the microwave and thermal cure processes, respectively. No evidence was found for any specific effect of the microwave radiation on the rate parameters, and the systems were both found to be characterized by a negative substitution effect [99]. 

Commercial cement modifiers used were based on a bisphenol A-type epoxy resin, diglycidyl ether of bisphenol A (DGEBA), which was mixed with three types of hardeners, modified polyamide-amine (MPAA),modified aliphatic polyamine (MAPA).and modified amine (MA) at the hardener contents recommended by the respective manufacturers. The hardener content was expressed as follows ... 

The homonuclear 2D 7-resolved experiment was also used as an aid in assigning resonances in the epoxy resin diglycidyl ether of bisphenol-A [73] and the com-... 

Figure 2. Solid-state spectra of four different epoxies (hosed on the resin diglycidyl ether of bisphenol-A) are compared with the liquid-state spectra of their respective unreacted components, The chemical compositions are in Table I. Here the epoxies are identified by their main curing agent (a) PIP—piperidine (b) MPDA—metaphenylene diamine (c) HHPA—hexahydro-phthalic anhydride (d) NMA—nadic methyl anhydride.

Creasy [260] has compared thermal pyrolysis, laser microprobe and CW laser pyrolysis of a cured, fire retardant epoxy resin (diglycidyl ether of tetra-brominated bisphenol A). Laser ablation/electron impact (LA/EI) produced mostly low-MW fragments that gave limited information about the material. The relationships and analytical value of these techniques were discussed. The same author [167] has used LD/EI-FIMS for the analysis of oligomers. 

Numerous avenues to produce these materials have been explored (128—138). The synthesis of two new fluorinated bicycHc monomers and the use of these monomers to prepare fluorinated epoxies with improved physical properties and a reduced surface energy have been reported (139,140). The monomers have been polymerized with the diglycidyl ether of bisphenol A, and the thermal and mechanical properties of the resin have been characterized. The resulting polymer was stable up to 380°C (10% weight loss by tga). 

Epichlorohydrin and Bisphenol A-Derived Resins. The most widely used epoxy resins are diglycidyl ethers of bisphenol A [25068-38-6] (1) derived from bisphenol A [80-05-7] and epichlorohydrin [106-89-8],... 

The pure diglycidyl ether of bisphenol A [1675-54-3] DGEBA is a crystalline soHd (mp 43°C) with a weight per epoxide (WPE) = 170. The typical commercial unmodified Hquid resins are viscous Hquids with viscosities of 11—16 Pa-s (110—160 P) at 25°C, and an epoxy equivalent weight of ca 188. 

Advancement Process. In the advancement process, sometimes referred to as the fusion method, Hquid epoxy resin (cmde diglycidyl ether of bisphenol A) is chain-extended with bisphenol A in the presence of a catalyst to yield higher polymerized products. The advancement reaction is conducted at elevated temperatures (175—200°C) and is monitored for epoxy value and viscosity specifications. The finished product is isolated by cooling and cmshing or flaking the molten resin or by allowing it to soHdify in containers. 

Applications with real composites have been performed in order to verify the results so far outlined. Namely, a metalfilled epoxy composite was selected, whose matrix material was a diglycidyl ether of bisphenol-A resin, cured with 8 percent by weight of the resin, triethylene-tetramine. 

Diglycidyl ether of bisphenol A (DGEBA, MW 340 Da) and 4,4 -dihydroxy-diphenylmethane (DHDPM, MW 200 Da) were analysed by SEC-MALS [784]. DGEBA and DHDPM are the basic oligomers of epoxy resins and phenol-formaldehyde condensates, respectively, which are widely used in the electronic and automotive industries. Excellent reproducibility ( 1 %) and good accuracy (better than 10%) were observed. SEC has also been used for the determination of mineral oil in extended elastomers [785] and in PS [178]. With heptane containing 0.05% isopropanol as the mobile phase, mineral oil is completely unretained and elutes before the solvent via SEC all other components in a PS extract are retained on silica and elute after the solvent peak. 

Yamani and Young (5) applied the theory to explain the plastic deformation of a diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured with various amount of triethylene tetramine (TETA). They found that the theory gave a reasonable description for the resins below the glass transition temperatures T. ... 

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