A NEW PLASTIC

Greymouth Evening Star, 2 June 1937, Page 8

A NEW PLASTIC

MANUFACTURE OF LUCITE. Members of the New York Patent Law Association were given a demonstration at their annual dinner recently of Lucite, a crystal-clear plastic, the latest product of chemical research and already the foundation of a new industry (states the “Christian Science Monitor”). Formerly known as Pontalite, Lucite is manufactured by the du Pont Company and has been characterised

by attorneys and technicians alike “a .veritable gold mine of surprise.” Many o£ the optical qualities equal the purest quartz crystal, yet the plastic after manufacture can be cast, cut, cemented, carved, drilled, moulded, sawed, or polished. It resists concentrated hydrochloric or sulphuric acid solutions as high as 50 percent., and, like quartz, it has edge lighting facilities, transmitting light around a bend without lighting up the course. In addition, it transmits a large portion of the sun’s ultraviolet light, eliminated by ordinary glass. Freedom from colour permits fabrication into delicate tinted shades. Stuart P. Miller, of the du Pont

Company, was in charge of demonstrations before the patent attorneys. Illustrating its quartz-like properties, he placed a mass of the thermoplastic resin, Lucite, over a light, treating a quartz crystal in the same way. From the light soijrce came various wave lengths of light regulated by Corning filtered glasses of red, yellow, green, blue, and violet, which were projected through the crystal and plastic masses. Because each of these materials has the same property of propagating light within itself, and because the internal fractures of the two masses are at various angles, the light was reflected from such interior surfaces in a myriad of colours

The effect was a beautiful mixture of constantly-changing colours in which the light appeared to travel sometimes in. waves, sometimes as if tracing a. path along a line line in the crystalline or plastic mass, and at other times by alternate fading and' glowing, bursts of colour were effected as though from an open fire. The demonstration was intended to show that the plastic seems to have the same structural formation as that of rock quartz crystal so far as optical qualities are concerned. In another demonstration the phosphorescence of Lucite was dramatically shown. The house lights were turned off, following which a rod of the plastic was exposed in front of a mercury vapour ultra-violet lamp for 60 seconds. During this time, it was explained, the plastic absorbed ultraviolet rays. The rod was then waved in the air, and for al least 10 seconds a brilliant blue-green phosphorescence shone in the dark.

Though interesting, this particulai property of Lucite has no commercial value; the demonstration being given to emphasise the fact that research work may develop characteristicsand qualities tor which no purpose is known at the lime, but which may prove useful in the future. Mr .Miller explained that imperfections such as bubbles or inside blisters. specks of dirt, or foreign matter not. readily apparent nor visible in opaque materials are readily discernible in transparent Lucite, hence extreme cleanliness must be exer-

cised in handling it during manufacturing processes. In addition, just the right heat must be applied during casting, not less than flttdeg. Centigrade nor more than 115. though special moulding compositions can be prepared which can be softened at considerably lower temperatures.