Polymer-metal bond, nature

Naturally, fibers and whiskers are of little use unless they are bonded together to take the form of a structural element that can carry loads. The binder material is usually called a matrix (not to be confused with the mathematical concept of a matrix). The purpose of the matrix is manifold support of the fibers or whiskers, protection of the fibers or whiskers, stress transfer between broken fibers or whiskers, etc. Typically, the matrix is of considerably lower density, stiffness, and strength than the fibers or whiskers. However, the combination of fibers or whiskers and a matrix can have very high strength and stiffness, yet still have low density. Matrix materials can be polymers, metals, ceramics, or carbon. The cost of each matrix escalates in that order as does the temperature resistance. 

Other explanations of the nature of the polymer to metal bond include mechanical adhesion due to microscopic physical interlocking of the two faces, chemical bonding due to acid/base reactions occuring at the interface, hydrogen bonding at the interface, and electrostatic forces built up between the metal face and the dielectric polymer. It is reasonable to assume that all of these kinds of interactions, to one degree or another, are needed to explain the failure of adhesion in the cathodic delamination process. 

At present, the role of water in this type AFR polymerization is unclear. It seems likely that water changes the nature of the complex or solvating nature of the active ends of the anionic chain. Because of the hydrophobic aliphatic polymer chain, a polar compound such as water probably can approach the catalyst site to solvate or complex the environment of the active center without destroying the C—metal bond. This water barrier may prevent water-insoluble monomer from penetrating the reaction site, while with a water-soluble acrylate, the presence of the... 

In Thermal spray processes the nature of the process was described here, applications to adhesion are presented. Thermal spray coatings for applications involving adhesion are in three general areas, metallic bond or anchor coating, ceramic bond coat, and sprayed polymer as the adhesive. In many cases, the surface modification by the deposition of a thermally sprayed coating is an alternative to environmentally hazardous methods. The thermal spray process is a dry process in which the effluent is collected in a dry cartridge system and usually recycled. 

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