The Technology Involved in Using Elastomeric Adhesives

Of the eight types of elastomeric adhesives presently used, the most common are rubber-latex protein adhesives, elastomer-phenolic adhesives, contact cements, and polysulfide-epoxy adhesives. These adhesives are combinations of two major ingredients capable of acting as adhesives alone, one with an affinity for polar surfaces and one with an affinity for nonpolar surfaces. The elastic properties of the mixture allow for differential expansion of the bonded materials — for example, of wood and metal subjected to changes in temperature and humidity. The two adhesive materials themselves are compatible, or at least are capable of forming interlocking matrices that hold tightly to each other to complete the bond. Two-step systems of gluing are actually nothing more than mixing the rigid and the flexible component in a glueline rather than in mixing equipment. Contact cements are generally based on neoprene rubber; in rubber-latex protein glues, neoprene latex is combined with ammoniacal solutions of casein or blood albumen; principle elements of elastomer-phenolics are butadiene acrylonitrile rubber and phenolic resin and mixtures of neoprene rubber and phenolic resin; rubber cement is composed of solutions of milled natural rubber in hydrocarbon solvents; polysulfides epoxy adhesives are mixtures of polysulfide monomers and ethoxylene resins. The surface chemistry of these adhesives varies from simply mechanical adhesion to complex reactions of wetting and bonding. Blends of co-polymers do not provide any advantages generally, though they may be used to solve problems in special cases.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member