Cyanoacrylate bonding natural rubbers

Durability. Cyanoacrylates suffer from poor heat and moisture durability. This failing is pronounced on metal adherends, but minimal on most plastic or rubber adherends. Poor heat resistance is due to several causes the thermoplastic nature of the polycyanoacrylate, the tendency to retropoly-merize, and the loss of adhesion experienced on heat aging of cyanoacrylate bonds. The poor moisture resistance is due in part to the hydrolytic degradation of the polymer and in part to the loss of adhesion caused by exposure to moisture. 

Polychloroprene, nitrile, natural rubber (polyisoprene), styrene butadiene rubber (SBR) and butyl are amongst the types of rubber that can be readily bonded with cyanoacrylates. Ethylene propylene diene monomer (EPDM) and fluroelastomers (Viton, registered trade mark of DuPont) can also be bonded, although only with specific grades of cyanoacrylate. Silicone rubber and thermoplastic rubber (Santoprene, registered trade mark of Advanced Elastomer Systems) can be bonded with the aid of a primer. Typical applications and techniques for bonding different grades of rubber are discussed in Section 10.11. 

Cyanoacrylates bond well to nitrile, polychloroprene and natural rubbers and fast bonding times can be achieved with ethyl cyanoacrylates (see also Section 10.1). Mould release agents however, can sometimes affect the adhesion and further practical guidelines are given in Section 10.12. 

As with most elastomers, natural rubber can be readily bonded with cyanoacrylates although in these trials [2] the adhesion achieved with the toughened cyanoacrylates was relatively low (Table 4.7). 

Adhesives used to bond acetal homopolymer (Dehin ) to itself and to other materials, such as aluminum, steel, natural rubber, neoprene rubber, and Buna rubber, include polyester with isocyanate-curing agent, rubber-based adhesives, phenohcs, epoxies, modified epoxies, and vinyls. Solvent cementing cannot be used unless the surfaces are specially roughened, because of the high solvent resistance of this material [23]. Other adhesive types sometimes used are resorcinol, vinyl-phenolic, ethylene vinyl acetate, cyanoacrylates, and polyurethane. 

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