Cyanoacrylate adhesives advantages

Advantages of cyanoacrylate adhesives include rapid curing, solvent-free nature, high bond strength, versatility, solvent resistance and their comprising only one part. 

Further details regarding the advantages and limitations of different adhesives are given in articles already cited and in the articles listed below. Other sources include Refs. [2-4] and works discussed in the Appendix. See also Adhesive classification, Anaerobic adhesives, Cyanoacrylate adhesives. High-temperature adhesives, Rubber-based adhesives. 

Cyanoacrylate adhesives J GUTHRIE Anionic polymerization, additives, applications, advantages and disadvantages... 

Many of the advantages of cyanoacrylate adhesives have been previously discussed, and derive from their unique combination of attributes. Still a summary of these is in order. They include ... 

Cyanoacrylate adhesives are single-part, solvent-free polymerizable adhesives. They start to cure within seconds by adsorbed moisture or by alkaline sites on the substrate, which can be nearly any solid or semisolid material. They have the advantage that no by-products are released during cure. 

These acids can be used alone or as mixtures. It is especially advantageous to use a mixture of liquid and gaseous acids. The gaseous acid will stabilize free monomer in the headspace of a container, while the liquid acid will prevent premature polymerization of the bulk monomer or adhesive. However, it is important to use only a minimum amount of acid, because excess acid will slow initiation and the formation of a strong adhesive bond. It can also accelerate the hydrolysis of the alkyl cyanoacrylate monomer to 2-cyanoacrylic acid, which inhibits the polymerization of the monomer and reduces molecular weight of the adhesive polymer. While carboxylic acids inhibit the polymerization of cyanoacrylate monomer, they do not prevent it completely [15]. Therefore, they cannot be utilized as stabilizers, but are used more for modifying the reactivity of instant adhesives. 

All of the eommereial alkyl eyanoaerylate monomers are low-viseosity liquids, and for some applications this can be an advantage. However, there are instances where a viseous liquid or a gel adhesive would be preferred, sueh as for application to a vertical surface or on porous substrates. A variety of viscosity control agents, depending upon the desired properties, have been added to increase the viscosity of instant adhesives [21]. The materials, which have been utilized, include polymethyl methacrylate, hydrophobic silica, hydrophobic alumina, treated quartz, polyethyl cyanoacrylate, cellulose esters, polycarbonates, and carbon black. For example, the addition of 5-10% of amorphous, non-crystalline, fumed silica to ethyl cyanoacrylate changes the monomer viscosity from a 2-cps liquid to a gelled material [22]. Because of the sensitivity of cyanoacrylate esters to basic materials, some additives require treatment with an acid to prevent premature gelation of the product. 

Gelatin-resorcin-formaldehyde adhesives (GRF) have been studied 38-40>. These adhesives compared with cyanoacrylates have an advantage in that they join tissues reliably under conditions of a moist operative area and undergo rapid degradation in the organism. The rate of curing is adjusted easily by changing the ratio of components. 

The viscous isoamyl cyanoacrylate shows the least deterioration of bond strength to bone in an aqueous environment. This material has the further advantage that (1) it may be more suitable for applications where some filling of a gap by the adhesive is required and (2) it is considered to be less toxic than the lower homologues of the 2-cyanoacrylate series. 

Moisture-curing adhesives are formulated with resins that react with atmospheric moisture to form a cured polymer. Most of these resins are one-part cyanoacrylates, silicones, or polyurethanes. The key advantage, of course, is their ability to cure without the use of heat or other external form of energy. However, in many cases, several days of ambient exposure are required to achieve full properties since the rate... 

N-butyl cyanoacrylate is the most commonly used cerebral AVM embolic material, and is considered by some to be the most effective (Finfante and Wakhloo, 2007). While its drawbacks include tissue adhesiveness and optimization of polymerization time, the main advantage of this material is its permanency. The curative capability of n-BCA, seen both after initial embolization... 

In the aerospace, aircraft, automotive, electrical, instrument, construction and marine industries, among others, modified acrylics offer distinct assembly advantages over high performance epoxies and urethanes, as well as anaerobic structural adhesives and cyanoacrylates. 

Some of the curing adhesives require heat, whereas others react at room temperature with the help of catalysts, and in some instances with activation by light. Again, it is an advantage to make a bond without the aid of an oven. Among the adhesives which can be processed in the cold, with proper formulation, are resorcinol formaldehyde, unsaturated polyesters, methyl methacrylate, cyanoacrylate esters, epoxies, and urethanes. The polymerization reaction is usually exothermic, so that the glue line may become somewhat warmer than the ambient... 

Pinch valves are used for low-viscosity adhesives which are processed in the pressure range up to 10 har (O Fig. 38.9). The tube cross section is pinched in such a way by a pneumatically driven lever that the flow of adhesive is stopped. The advantage is that the actual valve mechanism does not come into contact with the adhesive. This type of valve is the preferred for processing anaerobically curing adhesives and cyanoacrylates. 

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