Soil Burial Tests: Effect of Soil Burial Exposure on the Properties of Molded Plastics

The molded plastics selected for soil burial tests represented a limited cross section of those commercially available at the time the program was started. Many of the materials evaluated are now being used in diverse telephone apparatus, including telephone sets, terminals, relays, covers, switches, connectors, underwater repeaters, and many other applications. It can be anticipated, as buried plant becomes more common, that many of these materials will be considered for underground applications. Any plastic used in a buried telephone plant system would represent a long-time investment and a minimum life expectancy of twenty years is not an unusual requirement. Therefore, before any applications are developed for employing plastics underground, it is necessary to assess the general effect of soil burial 011 the different plastics that are commercially available. Most molded plastics are synthetic organic compounds and subject to normal aging processes such as oxidation or hydrolysis. Continuous exposure to any of the overall complex soil environments, whether they are physical, chemical, or biological, may increase the rate at which these plastics age. Earlier studies have led 23