From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Various early plastic insulating materials, their manufacturing processes, and properties.
| Identifier | ExFiles\Box 24\2\ Scan100 | |
| Date | 25th January 1921 guessed | |
| - 13 - The treatment requires considerable practice and a number of artifices in order to obtain successful results. At any rate these processes have generally only reached practical success after overcoming great difficulties. The Rheinisch-Westfalische Explosive Company on Cologne, which works, according to the Eichengrun process, produces cellon substances in hard and pliable qualities both colored and colorless, and also varnishes of the same material. Following the increasing use of iron as a conductor it is requisite to provide this with a coating to protect it against rust, and cellon varnishes are very suitable for this purpose. They are not affected by oils, fats, petroleum and benzine and dry quickly cold. The insulation of armature coils and also bare wires may be covered with a coating of cellon varnish with advantage to the insulation. The hard cellon materials have a specific weight of 1.35 and, even after being ground possess an insulating resistance of about 10,000 ohms which is maintained after 24 hours immersion in water. The dielectric strength can reach 30,000 volts per mm. Cellon is hardly attacked by the acid of accumulators, and retains a good insulation under their action. Plates can be easily machined using a moderate power and may be provided with reliable threads. The wear on the tools is very small and the material takes a good polish. When exposed to a flame the material disintegrates and a half-carbonised sticky produce remains in which, in some varieties, a continuation of the combustion takes place. In boiling water cellon becomes elastic like rubber so that it can be moulded into any shape, and it can also be stuck. The tests are not complete to show the effect of ageing. It is possible that the structure may alter with time and a reduction of the insulation may take place of materials composed of acetylene-cellulose as also in materials called Bakelite, referred to below. Another process of Dr. Eberhard may be mentioned that uses cellulose as its raw material and produced horn-like insulating materials. Starting from cellulose combined with soda-lye and heating the combination with carbonic sulphide the thiocarbonate or xanthogenate of the cellulose is produced. This combination is very unstable under the action of heat acid and alkaline ammonium salts and easily changes into an unstable cellulose. Out of these, a plastic material called momite can be obtained by coagulation, having a tough composition and being completely unattacked by fats, oils, ether and benzine and having a good electrical insulation. This material can be easily machined, turned, pressed, drilled, glued, bent and polished. The Bakelite products have a similarly to cellulose. Bakelite is an artificial resin made synthetically from components of tar, the process being due to Dr. Baekeland. This investigator who has made considerable contributions to the province of electro-chemistry, was engaged in examining these substances that are produced by the action of phenol contd. | ||