Metals adhesive properties

Reactions with additives or metals (adhesion properties, staining, corrosion etc.) ... 

These monomers provide a means for introducing carboxyl groups into copolymers. In copolymers these acids can improve adhesion properties, improve freeze-thaw and mechanical stability of polymer dispersions, provide stability in alkalies (including ammonia), increase resistance to attack by oils, and provide reactive centers for cross-linking by divalent metal ions, diamines, or epoxides. 

The polymers of the 2-cyanoacryhc esters, more commonly known as the alkyl 2-cyaiioacrylates, are hard glassy resins that exhibit excellent adhesion to a wide variety of materials. The polymers are spontaneously formed when their Hquid precursors or monomers are placed between two closely fitting surfaces. The spontaneous polymerisation of these very reactive Hquids and the excellent adhesion properties of the cured resins combine to make these compounds a unique class of single-component, ambient-temperature-curing adhesives of great versatiUty. The materials that can be bonded mn the gamut from metals, plastics, most elastomers, fabrics, and woods to many ceramics. 

Solders should flow promptly and smoothly over the surfaces of the parts to be joined. This property depends on the surface tension, viscosity, and adhesive properties of the molten solder. Finally, the color of a solder should match that of the metal employed, and its physical properties should be at least as good as those of the metal, in order for the joint not to be a source of weakness (150). 

Nitrile rubber adhesives. The main application corresponds to laminating adhesives. PVC, polyvinyl acetate and other polymeric films can be laminated to several metals, including aluminium and brass, by using NBR adhesives. NBR adhesives can also be used to join medium-to-high polarity rubbers to polyamide substrates. The adhesive properties of NBR rubbers can be further improved by chemical modification using polyisocyanate or by grafting with methyl methacrylate. 

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

Salts of alkyl phosphates and types of other surfactants used as emulsifiers and dispersing agents in polymer dispersions are discussed with respect to the preparation of polymer dispersions for use in the manufactoring and finishing of textiles. Seven examples are presented to demonstrate the significance of surfactants on the properties, e.g., sedimentation, wetting behavior, hydrophilic characteristics, foaming behavior, metal adhesion, and viscosity, of polymer dispersions used in the textile industry [239]. 

The polyelectrolyte cements are modern materials that have adhesive properties and are formed by the cement-forming reaction between a poly(alkenoic acid), typically poly(acrylic acid), PAA, in concentrated aqueous solution, and a cation-releasing base. The base may be a metal oxide, in particular zinc oxide, a silicate mineral or an aluminosilicate glass. The presence of a polyacid in these cements gives them the valuable property of adhesion. The structures of some poly(alkenoic acid)s are shown in Figure 5.1. 

Uchida, M., Oyane, A., Kim, H.-M., Kokubo, T. and Ito, A. (2004) Biomimetic coating of laminin-apatite composite on titanium metal and its excellent cell-adhesive properties. Advanced Materials, 16, 1071-1074. 

Each painter had his own technique the binding medium was thus prepared using different additives, giving rise to a variety of recipes for each technique. For example, it is believed that fig latex (a white liquid exuded by the fig tree) was commonly added to the egg tempera, and that animal or plant resins were added to oil- and wax-based binders. On account of their adhesive properties, these materials were used not only as paint binders, but also as consolidants in restorations, as ingredients in varnishes used to finish paintings, and as ingredients of mordants to apply metallic leaf decorations. 

Each of these polymers exploit the ability of the group 10 metal catalysts used to tolerate functional groups and to copolymerise norbomene monomers bearing esters etc. into the polymer backbone. In the case of low-k dielectric polymers (Avatrel ) low levels (2-10 mol %) of 5-triethoxysilylnorbomene are used to impart good adhesive properties, the remaining 90+% of the monomer being a 5-alkylnorbomene. The alkylnorbomene is selected to tailor... 

Wet adhesion phenomena represent a potentially fruitful area of research since so little is known. Some of the important questions are (1) How does one measure quantitatively the magnitude of the adhesion when the coating is wet (2) What is the governing principle that determines whether or not water collects at an organic coating/metal interface (3) What is the thickness of the water layer at the interface and what determines the thickness A recent paper (1.) correlates the wet adhesion properties of a phosphated surface with the crystalline nature of the zinc phosphate at the metal surface. 

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. 

As a family of curing agents for epoxy resins, the amidoamines are lower in viscosity than the polyamides. They exhibit very good adhesive properties due to their chemical structure and easy penetration. Amidoamine cured epoxy adhesives have shown very good properties on concrete and other porous substrates. They cure extremely well under humid conditions. In fact amidoamine cured epoxy formulations have been used to cure underwater in certain applications. A typical general-purpose room temperature curing epoxy-amidoamine system is described in Table 11.7. This adhesive is used as a general-purpose metal-to-metal adhesive and body solder in the automotive industry. 

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. 

A typical formulation for a metal-to-metal adhesive-sealant that is cured with a combination of phthalic anhydride and pyromellitic anhydride is shown in Table 12.6. Table 15.9 shows the high-temperature properties of another epoxy formulation cured with pyromellitic dianhydride. Epoxy formulations cured with pyromellitic dianhydride (PMDA) show good short-term thermal stability in the temperature range of 150 to 230°C. 

Polvimide-Metal Interfaces. Several technological applications including semiconductor packaging and metallization demand a reliable and durable adhesion properties of the metal films. In the development of multilayer devices consist of alternating layers of metal and polyimides several reliable techniques are needed to study both thin films and their interfaces. The usefulness of the nuclear scattering techniques to study the metallization and the associated interfacial elemental diffusion processes under the effects of various temperature and humidity treatments on the metal-polyimide systems, such as Al, Cu, N, and Au on Du Pont Kapton type H have already been reported (21., 22.). Only a couple of examples are presented here to illustrate the ERD application. 

Metal thin films deposited on polymers are widely used in various industrial domains such as microelectronics (capacitors), magnetic recording, packaging, etc. Despite much attention that has been paid in the recent literature on the adhesive properties of metals films on polyimide (PI)( 1 - 5 ) and polyethyleneterephtalate (PET)((L) it appears that a better knowledge of the metal/polymer interface is needed. In this paper we focus ourself on the relationship between the adhesion and the structural properties of the aluminum films evaporated (or sputtered) on commercial bi-axially stretched PET (Du Pont de Nemours (Luxembourg) S.A.). A variety of treatment (corona, fluorine,etc.) have been applied in order to improve the adhesion of the metallic layer to the polymer. The crystallographic... 

In this paragraph we will examine first the adhesion properties and the structure of aluminum films evaporated i) on oi-axially oriented polymer and ii) on treated (corona and fluorine) polymer samples. Then, an analysis of the influence of some parameters of the metallization such as the thickness of the aluminum film, the evaporation angle and the aluminum deposition by sputtering, will be presented. 

If in the case of aluminized silicone we were able to evidence a drastic difference between sputtering and evaporation, it happens not to be the case for aluminized PET (13). Our preliminary results on this latter polymer indeed show no marked differences between the two deposition processes, both giving strong chemical interaction. By contrast we have also observed that with noble metals such as Au, no chemical interaction is taking place with silicone substrate with both deposition processes. This tells us that the nature of the polymer substrate and of the metal are most important for the interfacial and adhesive properties. The fundamental parameter seems to be the reactivity of both constituents of the interface. It has been confirmed by Pireaux et al. that the carboxylic function is one of the most reactive surface entity (14) and indeed for PET, the adsorption site for the Al atoms is found to be the carboxylic function (13). During this interaction, Al is oxidized and the diffusion of O into the Al film can occur. 

Solutions of chitosan salts are well known for their adhesive properties (53). Chitosan itself adheres well to nonconducting surfaces, such as paper, rayon, cellophane, wood, leather, rubber, and glass, but not to metal surfaces (57,58). For smooth surfaces, a stronger bond is formed by first applying a thin primer... 

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