Overview

There are innumerable items made for automotive, aerospace and industrial applications where elastomers are adhered to metal using adhesives that bond the rubber to the metal substrate during the vulcanisation cycle. Included are engine mounts, dynamic seals, automotive weatherstrip, various shock and vibration dampeners for down hole drilling, rubber covered rolls, pump impellers and solid rocket motors for missiles and space applications. If manufacturing or in-service adhesion failures occur, the reasons for the failure need to be understood so that corrective actions can be implemented. There can be different modes of failure. By properly investigating the nature of the failure, causes can be identified. In addition, the root cause of the failure must be discovered so as to prevent further problems in the future. In some cases, various surface analyses may be conducted using sophisticated techniques to determine the nature of the failure and the possible cause.

In the 1950s, two-coat adhesive systems consisting of a primer and a reactive topcoat were developed to bond a variety of elastomers to metals, textile and other substrates during the moulding operation. Here the adhesive coated substrate is placed in a mould cavity and rubber then moulded to it. During this vulcanisation step, the rubber cures, the adhesive cures, and adhesion is developed. The thermoset bond that is formed is expected to be stronger than the rubber and able to resist the same environments to which the rubber will be exposed. These environments include hot oils (such as for engine seals), salt...