Anaerobic adhesives advantages

Many anaerobie adhesives and sealants may require a relatively low strength so that the eomponents can be disassembled for repair or replacement. Many liquid plasticizers have been used for this purpose [62], but the use of a low-molecular-weight polyester has been found to be advantageous [63]. The toughness properties of anaerobic adhesives can be enhanced by the addition of a reactive elastomer [64]. The heat resistance of anaerobic adhesives and sealants can be enhanced by the addition of a bismaleimide... 

Anaerobic adhesives take extreme advantage of the air inhibition of acrylic polymerization. They are catalyzed in such a manner that they depend upon the presence of oxygen to remain an unpolymerized liquid. Cure is affected only in the absence of oxygen (1). 

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. 

Anaerobic adhesives offer an additional advantage in being available in a specific range of strengths based on the requirements of the MoD s DTD 5629-33 inclusive. So bonded assemblies may be made suitable for disassembly using conventional workshop equipment, or made permanent. 

This formidable list indicates quite clearly the care that needs to be taken in such a design. Nonetheless, the implementation of known successful designs has led to considerable savings and technical advantages. For example, unlike solder, the single-part epoxies and anaerobic adhesives do not creep at elevated temperatures and their performance can be better. 

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. 

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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