Soil Burial Tests: Effect of Soil Burial Exposure on the Properties of Adhesives and Pressure-Sensitive Tapes

Included in the Bell System study of direct soil burial effects on the properties of material for telephone plant were a number of adhesives and pressure-sensitive adhesive tapes. The 1950s and 1960s were a period of significant growth for adhesives technology, as witnessed by the number and diversity of products, applications, and publications related to the field. Few, if any, applications for buried adhesively bonded structures existed at the beginning of this program, but developments in t h a t direction were easily predictable. General usage of adhesives by the Bell System was initially cautious because of insufficient data and inadequate tests for evaluating 123 124 THE BELL SYSTEM TECHNICAL .JOURNAL, JANUARY 1972 durability and reliability of bonded assemblies. However, with the development of better test methods and greater understanding of environmental deterioration, telephone applications of adhesives have increased manvfold. Pressure-sensitive adhesive tapes have enjoyed a very rapid increase in usage within the Bell System. M a n y applications can be categorized as electrical insulations, such as splice protection, but more and more uses are being classed as mechanical holding, such as packaging, nameplate mounting, coil wrapping, duct sealing, leak stoppers, surface protectors, etc. All of the tapes selected for this program had been used for some form of cable splicing where outdoor exposure would be encountered. With the emphasis on buried plant, additional testing of tapes under direct soil burial was considered advisable.