Abstract
As long ago as 1853 it was found that rubber was a suitable addition to oils to improve their lubricating properties. Thus rosin oil was rendered suitable for lubricating machinery, locomotives, wagons, etc., by adding as much of a 1–2 per cent stock solution of rubber in rosin oil to further amounts of oil as deemed suitable. The rubber was cut in thin strips, masticated, and allowed to dissolve in the rosin oil in a hot water bath. A lower temperature could be used by prolonging the time of immersion. A subsequent patent and formulas in a book by Brunner, propose dissolving the rubber in turpentine and adding it to fish and vegetable oils in proportions of about 5–10 per cent. As will be shown later, these proportions are probably too large to be satisfactory, and moreover at that period the recipes were not economical. In 1855 a patent was taken out by Hyde, which in view of our own observations must be regarded as a very remarkable piece of work. After stating that mineral oils for lubricating machinery at temperatures of 600° F. or over require admixture with castor, sperm, or rape oil, he draws attention to the fact that, on keeping at 212° F., or for several days in sunlight, the mineral oils develop a sludge. The addition of rubber to mineral oils, he states, “exerts a most remarkable action in giving permanence to them … and at the same time improves the lubricating or truly oily character of the oil, and the changes under the influence of high heats or the sun's rays are in like manner retarded or prevented for a longer time so as to give a degree of permanency and lubrication such as no other known oil or mixture possesses when tested by lubrication indicators. When more than 2 per cent rubber is added the valuable qualities are in every case impaired, and even less than 1 per cent is usually all that need be combined; 0.5 per cent will give durability and lubrication much beyond that of sperm oil.” He introduced the rubber by suspending it in a cloth bag in the mineral oil at 80–150° F.
Possibility of refreshing binders in old asphalt pavements