Difunctional epoxy resin

Calculations for a branched advancement synthesis are defined to permit development of well-characterized functionality in the product molecules. In this study, the difunctional epoxy resin monomer used is the diglycidyl ether of bisphenol A, Epon 828, and the multifunctional epoxy phenol novolac resin used is DEN 438. Let ... 

The epoxy resin can be defined as any molecule that contains two or more alpha-epoxy groups which can be reacted to form a thermoset system. An example of a difunctional epoxy resin is diglycidyl ether of Bisphenol-A (DGEBA) which is formed... 

F. 4. TTT cure diagram temperature of cure vs. time to the isoviscous event, gelation and vitrification, including TBA and gel fraction data , isoviscous (TBA) O, gelation (TBA) A, vitrification (TBA) , gelation (gel fraction). The system studied was a difunctional epoxy resin, Epon 828 (DGEBA, Shell Chemical Co.), cured with a tetrafimctional aliphatic amine, PACM-20. (bis(p-aminocyclohexyl)methane, DuPont]... 

Fig. 7. T, vs. temperature of cure for dinerent times of cure. The solid lines are the best straight line fits to experimental data (symbols) the dashed lines are the extrapolations to T, to obtain the temperature of cure to reach full cure for the given time. The T, line is also included. The system studied was a difunctional epoxy resin, DER331 (DGEBA, Dow Chemical Co.), cured with TMAB (see Fig. 3 caption). (Peng, X., GiUham, J. K., Ref. )...

Thermoplastics are sometimes added to epoxy resins. Thermoplastic-modified epoxy resins [43,44] based on tri- and difunctional epoxy resins cured with DDS and blended with polyethersulfone form the basis for the matrix material in a composite used for the Boeing 777 aircraft. The incorporation of the thermoplastic helps the processing characteristics and also improves the mechanical properties, notably the toughness. The thermoplastic is able to phase separate from the epoxy phase and acts as a reinforcement for the epoxy matrix, enhancing its high temperature properties. The maximum use temperatures of all these resins will typically be 30 to 50 degrees lower than the cited Eg, assuming the same cure schedule. 

Par Park, S.-J., Heo, G.-Y., Lee, J.-R. Thermal properties and fracture toughness of difunctional epoxy resins cured by catalytic initiators. Polymer Korea 26 (2002) 344-352. 

OSaJin Jin, F.-L., Park, S.-J. Fracture toughness of difunctional epoxy resin/thermally latent initiator system modified with polyesters. J. Industrial Eng. Chem. 14 (2008) 564—567. 

Difunctional Epoxy FIGURE 7.1 Reaction to form difunctional epoxy resin. 

Aliphatic Glycidyl Ethers. Aliphatic epoxy resins have been synthesized by glycidylation of difunctional or polyfunctional polyols such as a 1,4-butanediol, 2,2-dimethyl-l,3-propanediol (neopentyl glycol), polypropylene glycols, glycerol, trimethylolpropane, and pentaerythritol. 

Gel-permeation chromatography studies of epoxy resins prepared by the taffy process shown n values = 0, 1, 2, 3, etc, whereas only even-numbered repeat units are observed for resins prepared by the advancement process. This is a consequence of adding a difunctional phenol to a diglycidyl ether derivative of a difunctional phenol in the polymer-forming step. 

Step-growth, or condensation, polymers are usually formed in a reaction between two monomers, each of which is at least difunctional. Polyesters, polyamides, polyurethanes, and epoxy resins are typical examples of step-growth polymers. These polymers grow by steps or leaps rather than one monomer unit at a time. 

In a heat-cured epoxy resin system, the hydroxyls generally react with either epoxy or acid groups. Hence, heat-cured diepoxies can be regarded as being potentially tetrafunc-tional, rather than difunctional. Conventional diepoxy resins, therefore, yield much more highly crosslinked structures with higher heat and chemical resistance after heat cure than after room temperature cure. 

Difunctional epoxy diluents are low-viscosity, low-MW epoxy resins. These diluents may be used at very high concentrations, and they do not greatly affect the properties of the cured resin. In some instances the difunctional epoxy diluents will actually improve properties. These materials include butadiene dioxide, vinyl cyclohexane dioxide, and diglycidyl ether of resorcinol. 

The polymerization in the discrete phase is an anionic addition between the difunctional liquid rubber and the epoxy resin which gives a linear block copolymer. Thus the selectivity and reactivity of the end groups of the liquid rubber are critical. 

An ASA-PBT with improved hydrolysis resistance and reduced warp was reported for a resin composition containing a difunctional epoxy compound such as bis(3,4-epoxycyclohexylmethyl) adipate [81]. To increase the heat distortion temperature of a PBT-ASA blend by 10-20°C, the addition of talc at a... 

For difunctional phenolics, such as biphenol and bisphenol ethane, two moles of epoxy resins are reacted with the difunctional phenolics to form an adduct. 

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