Importance of Temperature and Humidity Control in Rubber Testing. I—Stress-Strain and Tensile Properties

IN OCTOBER, 1926, R. P. Dinsmore, chairman of the Rubber Division of the AMERICAN CHEMICAL SOCIETY, appointed a Physical Testing Committee to investigate the effect of variables such as temperature and relative humidity upon the physical properties of rubber. This committee was continued by Harry L. Fisher, present chairman of the Rubber Division. The committee chose the problem of determining the importance of controlling atmospheric temperature and relative humidity while conditioning rubber test samples at various stages of preparation and testing. This report deals with the first study made—that of the effect of the above two variables on the stress-strain and tensile properties of rubber. In reading this report it should be kept in mind that the problem of this committee is to determine the effect of variables on the physical properties of rubber so that we may know the relative importance of controlling the factors involved. It was not intended to make this work include the relative value of specific tests for particular purposes or to become a research directed towards the development of new tests. It has been the intent to limit the work of the committee to the refinement of tests widely used and considered as routine and standard, and not to include development of new tests or work concerning broader lines of research. It is, however, hoped that in the future the work of this or another committee can be broadened to include fundamental research problems as well as specific work such as the present committee has undertaken. We believe that the work done demonstrates the desirability of carrying on cooperative investigations of this nature and hope that this committee is made a permanent institution of the Rubber Division with such changes in personnel as are necessary continually to broaden and improve the work. This report will raise many questions and point out several possible lines of research, but the committee has tried to stick to its job of determining the relative importance of controlling temperature and relative humidity in relation to stress-strain and tensile properties. The work has been carried out at the Bureau of Standards at Washington by F. E. Rupert as a research associate under the direction of the committee. The Bureau of Standards has contributed its facilities and to cover the expenditures of the committee for the first year each company represented by the members of the committee contributed $650. The Rubber Association of America is handling the finances of the committee for the present year, which amounts to $6000 and includes the appropriation of the Firestone Tire and Rubber Company. As the committee has needed special apparatus different companies have loaned machines, which have included a Scott tensile tester and U. S. abrasion machine from the Henry L. Scott Company, and a Grasselli abrader from the Grasselli Chemical Company.