472 CURRENT TOPICS. [J. F. I.

ARMY AND NAVY~NOTES.

Ethyl Cellulose Production Doubled to Meet War Needs.--(Manufacturers Record, Vol. 112, No. 9.) Production of ethyl cellulose, one of the newest and most important in the family of cellulose derivatives, has been doubled at the Hopewell, Va., plant where it is made in the world's largest chemical cotton plant. Because of its special properties, it has found wide application in war uses, with a postwar future that seems equally bright.

A rapidly developing and very important use for ethyl cellulose, due to high impact resistance, is in hot-melt plastics for making dies and jigs for forming tools for shaping aluminum. This process is very economical because the plastic is light in weight and can be remelted and recast in different molds. This saves time in change-over on design and also saves machining operations.

It is also used for coating insulating wires of airplane engines because, in addition to excellent electrical properties, it will not snap under frigid con- ditions of sub-zero stratosphere cold and quick temperature change. Extruded ethyl cellulose plastic is also being used in cable cores.

In addition, brightly colored squares of cloth, used to identify Army ground equipment and prevent American planes from attacking their own troops are coated with ethyl cellulose. These patches of cloth, some of them only a few feet square, can be seen two miles up by fighter planes going at top speed.

The present uses for ethyl cellulose are strictly in line with its inherent properties. Where performance specifications have been set up for a thermo- plastic material to meet the rigors of field operations in both freezing and tropic conditions, such as the Signal Corps flashlight and the QMC canteen, ethyl cellulose has out-performed the other materials submitted and has been used.

It has exceptional dimensional stability under troublesome weathering conditions, such as heat and humidity. It can resist the lowest freezing tem- peratures better than "any known plastic and yet be formulated to stand tem- peratures as high as 175 ° F., and, in addition, it possesses remarkable impact strength.

These important properties are supplemented by other factors of almost equal importance. It has the lowest density of any of the cellulose products, meaning lighter weight and more pieces per pound. It has a wide range of compatibility with chemical plasficizers, vegetable and mineral oils, waxes and resins; this offers a multitude of combinations. These many modifiers can be selected for best heat Istability, water insolubility, stability to light, hardness, flow, and other properties.

R. H. O.