Organometallic primers

Primers are often used to help ensure an adequate service life and, indeed, the presence, and the chemical type, of any primer may play a crucial role in ensuring a long service life for the adhesive joint. For example, it will be shown later that the use of organometallic primers may be extremely beneficial and many commercial corrosion-inhibiting primers have been developed for use with epoxy aerospace adhesives following the above comments, it is probably not just a coincidence that many of the latter types of primers contain phenolic-based constituents. Examples of the effect of substrate surface pretreatments on joint durability were shown in Figs 4.16 and 4.17 and Table 4.15 further examples are illustrated in Fig. 8.8. 

Two other points of interest are that it appears that such hydration inhibitors are only really effective on an aluminium alloy substrate which has already been pretreated by the CAE process. It would obviously be useful for the technologist if such simple primers were effective on a degreased or abraded surface. Secondly, the above work [82] also suggested that some silane-based primers could function as hydration inhibitors, so adding another possible mechanism whereby such organometallic primers might increase the service life of adhesive joints. 

Low surface energy substrates, such as polyethylene or polypropylene, are generally difficult to bond with adhesives. However, cyanoacrylate-based adhesives can be effectively utilized to bond polyolefins with the use of the proper primer/activa-tor on the surface. Primer materials include tertiary aliphatic and aromatic amines, trialkyl ammonium carboxylate salts, tetraalkyl ammonium salts, phosphines, and organometallic compounds, which are initiators for alkyl cyanoacrylate polymerization [33-36]. The primer is applied as a dilute solution to the polyolefin surface, solvent is allowed to evaporate, and the specimens are assembled with a small amount of the adhesive. With the use of primers, adhesive strength can be so strong that substrate failure occurs during the course of the shear tests, as shown in Fig. 11. 

M. Bochmann, Organometallics 1 and 2. Complexes with Transition Metal-Carbon c- and Tt-bonds, Oxford Chemistry Primers, Oxford, 1994. 

Whyman, R. (2001) Applied Organometallic Chemistry and Catalysis. Oxford Chemistry Primers 96. 

From Heterogeneous Ziegler-Natta to Homogeneous Single-Center Croup 4 Organometallic Catalysts A Primer on the Coordination Polymerization of Olefins... 

Atomic spectroscopy (including atomic absorption spectrometry, atomic emission spectrometry, and atomic fluorescence spectrometry) is of use across the span of reactive adhesive technologies. For example, the cure of anaerobic adhesives on non-reactive surfaces is usually assisted by the use of an active metal-based primer. Similarly, the cross-linking of silicone adhesives is promoted by the use of organometallic salts of cobalt, tin, iron, lead, and platinum. In the case of polyurethane adhesives, the key condensation reactions are catalyzed by tin salts (e.g., dibutyl tin dilaurate and stannous octoate). 

One technique for establishing interfacial primary bonds has been the use of organometallic silane-based primers, as discussed in Sections 3.5.4.2 and... 

The usable primer systems consist of a polymer binding agent matrix, a mixture of functional fillers, an organometallic palladium compound as catalyst for subsequent copper plating, diverse fillers for rheological adaptation to the application technique used, and a suitable solvent mixture [48]. 

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