File:Bell telephone magazine (1922) (14569389899).jpg

Identifier: belltelephonemag4344amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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ive agents: detergents and soaps.The obvious answer, of course, is to avoidsuch agents. The problems of regulating molecularsize and of finding proper lubricants forthe sheath where necessary were solvedat the Laboratories in a very short time.They had to be: there was a lot of moneyinvolved. We still have some cracking inpolyethylene sheaths and were still try-ing to find ways to avoid it; all of ourproblems are not yet solved. But, in themain, the problems were recognized anddealt with in those early days. Polypropylene We are also interested in another poly-mer called polypropylene, which is close-ly related to polyethylene. Both are madeof molecular units which differ only inthat polypropylene consists of three car-bon atoms in each of the building blockswhereas polyethylene consists of ethyl-ene units of only two carbon atoms each.When polypropylene is polymerized,only two of the three carbon atoms areused in forming the main chain, whilethe third carbon atom sticks up off the 54
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This tensile lest luachine. capable oj u JU.OOO-pound pull, is used to test tensile strength ofplastic samples: this one being measured by Mrs. Shirley Stills is known as a polycarbonate. chain. This third atom can be arrangedalong this chain in two different forms:either a right-handed or a left-handedform. It makes all the difference in theworld whether these are all uniform alongthe chain: that is, all right- or all left-handed, or whether they are randomlyarranged in right- and left-handed com-binations. If they are randomly arranged,you have a rubber, but if they are uni-formly arranged, you have a hard, high-melting plastic. Were using this hard, high-meltingplastic now in the Bell System for many purposes—as a tape inside of cables, forexample. At present we are trying it outas a handset material because its hardand durable, light in weight and low incost. It is really a highly-branched poly-ethylene, a new relative of polyethylenethat didnt get into commercial produc-tion un

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