Properties epoxy adhesives

The discussion centers on how the epoxy adhesive properties depend on the processes that occur during each stage. Special attention is given to the three requisites for good adhesion wetting, solidification, and avoidance of internal stresses. These are fundamental and well-known factors that affect the quality of the adhesive bond. The objective here is not to... 

May, C. A., Physical Significance of Acid Anhydride Cure on Epoxy Adhesive Properties, SPE Transactions, vol. 3, 1963, p. 251 and Savia, M., Epoxy Resin Adhesive, in Handbook of Adhesives, 2d ed., I. Skeist, ed., van Nostrand Reinhold, New York, 1977. 

Epoxy phenoHc coatings either are made by blending of a soHd epoxy resin with a phenoHc resin or are the products of the precondensation of a mixture of two resins. A three-dimensional stmcture is formed during curing which combines the good adhesion properties of the epoxy resin with the high chemical resistance properties of the phenoHc resin. The balanced properties of epoxy phenoHc coatings have made them almost universal in their appHcation on food cans. 

The outstanding performance characteristics of the resins are conveyed by the bisphenol A moiety (toughness, rigidity, and elevated temperature performance), the ether linkages (chemical resistance), and the hydroxyl and epoxy groups (adhesive properties and formulation latitude, or reactivity with a wide variety of chemical curing agents) (see also Phenolic resins). 

The two-component urethane structural adhesives are among the most difficult to characterize, simply because of the widely varying properties that are possible. These adhesives may be rigid plastics similar in modulus to standard epoxy adhesives, with glass transition temperatures of the cured adhesive being approximately 60°C. 

Although the acrylate adhesives are readily available and studies have shown that they can produce reasonable bonding properties, they have the disadvantages of having high shrinkage, high fluid absorption, and low service temperatures. Acrylate adhesive applications would be limited. The development of EB-curable epoxy adhesives would have applications in the aerospace and automotive industry and potential wider uses. The most immediate application for these resin systems is composite repair of commercial and military aircraft. 

EB processing and rheological properties of EB-cured epoxy adhesives... 

The physico-mechanical, thermal, and adhesion properties of the synthesized polyfunctional PSs are dependent on the nature of functional groups in the aromatic ring. In this case, the following are properties of the chlorohydrin and epoxy groups highest elasticity, resistance to strike, and adhesion properties with carboxyl and olefinics. Furthermore, the—CO—CH=CH-—COOH group was provided new properties such as the photosensitive capability. Functionalized PSs obtained are characterized by their high thermostability, adhesion, and photosensitivity. 

The surface activation method, especially the gas mixture used, determines the chemistry of the surface and can thus promote the adhesion properties with epoxy adhesives. The following example illustrates the importance of the correct activation gas mixture. As is clearly illustrated by Table 16.6, oxyfluorination induces better adhesive properties than fluorination on PE with Pro-Struct 30/71. 

Epoxies are made from Bisphenol A and epichlorohydrin. They are tough, resistant to heat, and have good adhesive properties. They can be mixed on-site by adding a catalyst and filler to the already linked Bisphenol A/epichlorohydrin that causes the cross-linking and the sec in thermoset. 

The corrosion resistance and polymer-bonding compatibilities of the lonizable organophosphonates and the neutral organo-silanes are directly related to their inherent chemical properties. Specifically, NTMP inhibits the hydration of AI2O2 and maintains or Improves bond durability with a nitrile-modified epoxy adhesive which is cured at an elevated temperature. The mercaptopropyl silane, in addition to these properties, is compatible with a room temperature-cured epoxy-polyamide primer and also exhibits resistance to localized environmental corrosion. These results, in conjunction with the adsorbed Inhibitor films and the metal substrate surfaces, are subsequently discussed. 

Other effects were more selective. While recycle usually lowered impact strength and heat deflection temperat ire, pre-soaking polyamine recycle surprisingly improved both of these properties. While recycle usually lowered volume resistivity, polyamide recycle improved it. Finally, adhesion of epoxy formulations to the aluminum mold, in spi/ e of wax and silicone mold release agents, was dramatically increased by the use of presoaked recycle, especially in the ai ydrlde system, suggesting unexpected usefulness in epoxy adhesive formulations. 

The thermoset included here is derived from bisphenol-A dicya-nate. It can be thermally trimerized yielding a triazine or cyanurate network (8,9,10) as seen in the reaction scheme (Table 1). The critical molecular weight between crosslinks is relatively low, resulting in an extremely tight, brittle network. The material is usually used as a prepeg because a total cure produces a hard, infusible, and insoluble matrix. It possesses excellent adhesive properties and is currently used as a metal coupling agent. It offers many superior properties relative to conventional epoxies derived from bisphenol-A. 

Why do PUs and epoxy resins have good adhesive properties ... 

Adhesives have been classified according to their applications. Epoxy is a compatible adhesive for stainless steel and ceramics, as used in the piezoelectric motor industry. Epoxy adhesives of different characteristics are found. Epoxy-polysulfone and epoxy-phenolics both exhibit thermosetting properties, providing stronger bonding properties with ceramics. 

High adhesive properties As explained earlier, electromagnetic bonding forces, chemical reaction and relatively less shrinkage lead to strong bonds between epoxy resins and composite propellants and that is why epoxy resins are preferred for inhibition of composite propellants [337-339]. 

Presently DOE is funding Air Products Chemical Company for the development of a fluorine surface treatment of tire rubber (crumb rubber) to modify its adhesion properties. This modified rubber could be used in making polymers such as polyurethane and epoxies. The tire rubber might also be used in certain plastics such as polystyrene and PVC, and in rubber products (68). 

Lucite positive relief structures. Epofix was selected as the chip substrate, among acrylic-polyester resin (Casolite) and epoxy resin (Araldite), because of its having the best mechanical properties and the least chemical interference needed for fabricating the MS chip [780]. In another report, PDMS was chosen over epoxy to fabricate MS chips because of its less chemical noises (interferents) in MS, and over polyurethane because of good adhesion properties. Even so, in the use of PDMS its curing (at 70°C) should be carried out for at least 72 h to further reduce the chemical noise [800]. 

Epoxy resins. The epoxy resins possess excellent adhesive properties and are often used to seal electrode materials into glass and plastic tubes (except Teflon). They will generally withstand temperatures to 200°C and are resistant to... 

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