Chemistry of epoxy resins

Kay and Fust postulated the use of epoxy resin for inhibition of composite propellants [335] and as a consequence, epoxy resins were tried for the first time for the inhibition of HTPB-based composite propellants at Thiokol Corporation, USA. Subsequently, use of the amido-amine hardened modified bisphenol-A-based epoxy resin was reported as inhibitor for fluorocarbon-based composite propellants [336]. Epoxy resins are the most versatile resins for bonding applications for a variety of substrates. This is because of the following characteristics. 

In other words, epoxies are the most versatile of contemporary plastics and it is considered necessary to briefly describe their chemistry. 

Epoxy Resins The term epoxy refers to an epoxide group which is a three-membered oxide ring. An epoxy resin is defined as a molecule containing more than one epoxy group capable of being converted into a thermoset (cured) form. The simple structure of epoxy resin [Structure (4.37)] is  

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Epoxy Resins. The chemistry of epoxy resin adhesives is quite varied. However, the most widely used is that formed from the reaction of 4,4 -isopropyhdene diphenol (bisphenol A) [80-05-7] and epichlorohydrin [106-89-8] C H CIO. This epoxy resin is more commonly known as... 

Considering both the chemistry of epoxy resins and the reactants required to produce it, impurities, unreacted raw materials, catalyst and other monomeric species can be expected to be present in the resin in low levels (i.e. <100 ppm). Under the mechanical, thermal and chemical stress levels acting at the interface both during curing and after curing, concentration of these species at the interface could be quite high giving rise to an interface structure unrelated to the bulk. 

Discuss the chemistry of epoxy resins based on diglycidyl ethers of bisphenol A, their preparations, and crosslinking reactions with amines, dianhydrides, and dicyanodiamide. 

When used for industrial adhesive purposes, epoxy resins occur mostly in the construction industry, the assembly of cars, ships, and aeroplanes, the manufacturing of sports equipment, as well as in the optical and electronic industries. Much is similar between the chemistry of epoxy resins and acrylates. Both are (often) two-component systems. They are not sensitising when fully cured but frequently contain an amount of remaining monomer, which is enough to... 

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

The epoxy resins when mixed with the correct amine produce tough films which adhere closely to metal. The chemistry of these resins is considered in Sections 14.5 and 14.9. 

B. Ellis, Chemistry and Technology of Epoxy Resins, Blackie, Glasgow, United Kingdom, 1993. 

Ellis B (ed) (1993) Chemistry and technology of epoxy resins. Black Academic Professional, London... 

Sikes, A.M., Brady, R.F. (1990). Controlled shrinkage polymers Characterization of epoxy resins cured with spirobislaetones. J. Polym. Sci. Part A Polym. Chemistry 28, 2533-2546. 

A detailed discussion of the chemistry, production and physical properties of epoxy resins in terms of their application to molding compounds has recently been given by Helfand and Villani. 

H. Lee and K. Neville, Epoxy Resins, Their Applications and Technology, McGraw-Hill, New York, 1957 Handbook of Epoxy Resins. New York McGraw-Hill, 1967 Encycl. Polym. Sci. Technol. 6, 209 (1967) I. Skeist, Epoxy Resins. Princeton, New Jersey Van Nostrand-Rheinhold, 1958 M. W. Ranney, Epoxy and Urethane Adhesives. New Jersey Noyes Data Corp., 1971 G. R. Somerville and P. D. Jones, Abstr. 168th Am. Chem. Soc. Meet., Atlantic City, N.J., 1974 Abstract ORPL, 146 in the Organic Coatings and Polymer Chemistry Division (1974). 

Considering thermodynamics of adhesion, epoxy/novolac epoxy resins play a vital role for bonding applications especially for inhibition of composite propellants. In view of this fact, it is considered worthwhile to discuss the chemistry of epoxy/novolac epoxy resins in this section before we discuss other systems for this purpose. 

Radiation Chemistry of Phenolic Resin Containing Epoxy and Azide Compounds... 

Formulators in the adhesives industry do not normally manufacture epoxy resins. Generally, formulators buy epoxy resins, modify them with other materials, do similar compounding to the curative, and then package the product as a complete adhesive system ready for the end user. There are many excellent textbooks6-8 available giving information about the preparation, chemistry, and use of epoxy resins in general applications. It is not the intention here to go into such detail but to focus only on epoxy adhesive systems. 

Proper formulation of epoxy adhesives requires knowledge of the chemical reactions that lead to polymerization as well as the chemical and physical properties of both the uncured mixture and the cured material. This chapter reviews the general principles of epoxy resin chemistry including synthesis of the epoxy monomer itself and its possible polymerization reactions. 

However, one of the greatest advantages of epoxy resin chemistry is that epoxy resins can provide low-viscosity formulations without solvents. As a result, these 100 percent solids systems elude environmental regulations and production precautions that are required for a flammable material. 

The details of epoxy resin chemistry and various technologies are covered elsewhere (Lee and Nivelle, 1967 May, 1988 Oldring, 19%). 

Data adapted from Ellis, B., Ed. Chemistry and Technology of Epoxy Resins Blackie Academic and Professional Glasgow, 1993 Hamerton, I. Recent Developments in Epoxy Resins RAPRA Review Report Number 91, 1996 8 (7) Hamerton, L Hay, J.N. Structural polymers. Chapter 8. In Specialty Polymers, 2nd Ed. Dyson, R.W. Ed., Blackie Academic and Professional London, 1998, 200-250 Pilato, L.A. Michno, M.J. Advanced Composite Materials Springer-Verlag Berlin, 1994. 

Ellis, B. Introduction to the chemistry, synthesis, manufacture and characterization of epoxy resins. In Chemistry and Technology of Epoxy Resins, Ellis, B., Ed. Blackie Academic Professional Glasgow, 1993 1-36. 

Hydantoins, thiohydantoins, and their substituted products are particularly useful as catalysts and as stabilizer agents in polymer chemistry and also in the preparation of epoxy resins.356,357 Thus hydantoins 148 are readily hardened, giving suitable polymers for the preparation of molding and lacquers. 

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