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By incorporating the spectroscopic techniques of reflection‐absorption and internal reflection in the infrared region, we have been able to define and characterize overall chemical changes occurring at a metal‐polymer interface. Our initial studies have concentrated on the oxidative degradation of metal‐polymer systems. These systems are of particular importance because of the common need to retard the metal‐catalyzed degradation of the polymer. Preliminary results for copper‐polyethylene interfaces, models for polyolefin‐insulated cable, have shown the copper surface to be the site of the initial catalysis in the oxidation of the polyethylene. When copper deactivators are added to inhibit the oxidation, initial reactions between the copper surface and the inhibitor can be seen. The importance of these surface reactions highlights the necessity for studying the interface.

The thermal stability of polyethylene containing conventional antioxidants is adversely affected by contact with copper, by certain pigments, and by the addition of a few percent of polypropylene as a processing aid. Polyethylene inhibited with 0.1% of phenolic antioxidants has approximately the same oxidative stability when in contact with a copper surface as the unprotected polymer. A mechanism is suggested to account for the loss of stability in the presence of copper. Pigments vary in the extent to which they adversely affect the oxidative stability of polyethylene. Since several factors may combine to decrease the stability of protected polyethylene compositions, as determined by accelerated tests, it is essential that their contribution under service conditions be determined. The predicted life at temperatures encountered in service is determined by extrapolating accelerated test data to that constant temperature which is calculated to cause the same degree of degradation as would occur during the daily and seasonal temperature cycles encountered in use.

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