ASTM D611 Aniline Point and Mixed Aniline Point of Petroleum Products and Hydrocarbon Solvents
The Aniline Point is the lowest temperature at which equal parts of aniline and oil are completely miscible. It is an indicator of the quantity of aromatic hydrocarbons in the oil and is useful in predicting an oil’s compatibility with natural or synthetic rubber. Aromatic compounds in an oil may cause some components of rubber to leach out, thereby weakening the rubber. Only oils with low aniline numbers are usually considered for natural rubber applications.
In this test, equal amounts of aniline and sample are blended and heated to obtain a clear solution. The mixture slowly cools. The temperature at which cloudiness first appears is reported as the aniline point.