Is a Plastics Age Coming ?
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THE word most in the mouths not only of engineers but of the public is "plastics." An unfortunate word, in the opinion of many, undescriptive of the wonderiul and varying properties of -the hundreds of compounds bearing it ; capable of forming the basis of articles of great beauty.. and -possessing who knows what remarkable potential attributes, already beginning to bring themselves to the notice of structural engineers, with tensile strengths varying from 2 tons per sq. in. to 85 tons in the case of certain fibre plastics.
Tensile strength alone, of .course, does not mean everything, but the rate of progress with this class of material rules nothing out as impossible. When 35-tons tensile is mentioned we immediately think of steel, but some other important properties do not yet correspond.
Probably the most promising for constructional purposes are the resin-impregnated laminated woods, as used for propellers. Such materials come close to the requirements of chassis frames for the battery-electric vehicle that may be coming into more -general use for short-distance duty after the war. It would permit of transferring the difference in weight (1 to 5 or 6, compared with steel) into the battery, thus making it possible to increase the distance per charge without raising . the gross weight of the sehicle.
Already, of course, plastics are used in many motor-vehicle components. chiefly in places where they do note form part of the structure but only covers or ornaments. An average •quantity in American practice is 10 lb. per vehicle.
, The new transparent plastics will undoubtedly be used in the future to replace opaque coverings, such as the roofs and sides of vehicles. Materials possessing the same. characteristic will also be used in places where internal inspection can be made through the thicknesiof the case, to save dismantling for the preliininary inspection. Electric motors suggest such an application ; there are many .others.
Corrosion resistance is a very valuable property of many plastics, and this will eventually account' for a wide extension of their use.
The potential uses for plastics are legion. Some types are still in their infancy, but they will grow amazingly fast in the days after the war. As they advance in quality and quantity, and their cost is reduced with bulk production, the fields which will then be open to them will present a vista the possibilitieS of which are almost beyond our conception.