Epoxy resin-curing agent combinations

Table 2.6. The most important epoxy resin-curing agent combinations and their uses...

The third approach has been the direct addition of epoxy resin and curing agent to cement. This can be accomplished, but generally requires the addition of 20% to 50% of the resin curing agent combination to obtain the desired properties. This approach is a compromise, resulting in a system which is economically impractical. 

Both polysulfone and the polyetherimide are thermojdaslics whieh withstand higher temperatures than epoxies such as DGEBA. The effect of (43) a polysulfone (Udel, 43a) and polyetherimide (Ultem, 43b) thermoplastics on the properties of a tetra-2,3-epoxypropylamine, N,N,N, N -tetra-2,3-epoxypropyl-, -bis(4-aminophenyl)-p-diiso-propenylbenzene (HPT Resin 1071,43c) has been studied and also the effect of these thermoplastics on the resin di-2,3-epoxypropyl-9,9-bis (hydro phenyl)fluorene (HPT Resin 1079,43d). Both these resins have a stiff backbone and were developed for use as amatrix resin for advanced composites. They can be cured with the aromatic dianune, -bis(3,5-dimethyl-4-aminophenyl)-p-diisopropylbenzene (43e). These resin curing agent combinations exhibit greatly improved hot/wet performaiKe over that of traditional epoxies. 

Optimal joints can generally be fabricated by the correct combination of epoxy adhesive formulation (i.e., type of resin, curing agent, fillers, modifiers) and surface treatment process. 

Polyalkylene polyamines find use in a wide variety of applications by virtue of their unique combination of reactivity, basicity, and surface activity. With a few significant exceptions, they arc used predominantly as intermediates in the production of functional products. End-use profiles for the various ethyleneamines include fungicide, oil and fuel additives, polyamides/epoxy curing, paper resins, chelaiing agents, fabric sofieners/surfactanls, petroleum production, bleach activator, and anlhelmimics/pharmaceulicals. 

C. Epoxy ROSins. The epoxy resins are thermosetting plastics which have great strength and the ability to form tenacious bonds with most surfaces. Furthermore, the cured resin is resistant to many solvents and chemicals. (Some epoxy resins are decomposed by acetic acid, and all are attacked by very strong oxidizing agents.) Because of this combination of properties, epoxy cements are frequently used to bond metal, glass, wood, and plastics. 

When high-molecular-weight solid epoxy resins are employed, they may be reduced to powder and then combined with a powdered curing agent. 

For maximum heat resistance, pyromellitic dianhydride is often used. The composition and properties of metal-to-metal adhesives based on a combination of epoxy novolac and a bisphenol A epoxy resin have been described in Sec. 12.5.1. Depending on the cure temperature and the choice of amine curing agent, strength as high as 3000 psi at room temperature and over 1000 psi in the range of-55 to + 150°C is possible. 

Epoxy resins are not ideal adhesives in their natural form so they are mixed with materials to improve and enhance their properties and, thereby, make them more useful in a variety of applications. This process is called compounding or formulating. Compounding is the combining of a base epoxy resin with curing agents, modifiers, additives, reinforcement, fillers, and other polymers to make the base polymer perform better, cost less, and process more easily. 

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