A big missing link in synthetic rubber a good, plentiful substitute for rubber in inner tubesappeared last week to have been found. U.S. synthetic rubbers or soft plastics have been developed to do almost every other job that natural rubber can do. Last week aircraft manufacturer Glenn L. Martin announced that his research men had developed a new plastic which makes better inner tubes than nat ural rubber ever did.
The new material, which has no chemical resemblance to rubber, is a vinyl chloride plastic with unusual elastic properties. It contains a plasticizer (unidentified) that enables it to keep its elasticity up...