Abstract
Evaluation that will predict with a high degree of accuracy the suitability for service of any product is the object of all physical testing. Over a comparatively short period of about twenty-five years, rubber technologists have evolved a series of tests which have evaluated natural rubber compounds reasonably well. When it became necessary to evaluate rubber substitutes, it was only natural that the same tests would be applied. The results obtained convinced everyone that these materials were definitely not equivalent substitutes, and to use them involved more than just replacement. Although the background is not so extensive as might be desired, the A.S.T.M. Committee D-11 on Rubber Products has learned enough about these materials to be able to present certain facts and recommendations to industry in general with regard to specifications covering synthetic rubbers and products made from them. The entire field of physical testing is quite extensive, as it covers not only finished products but the component raw materials from the time they are received until they emerge as final products ready to be put into service. Also, in this large field, not everyone is interested in the same phase of testing synthetic rubber products. Tire development engineers are not interested in load deflection figures, which are so essential to automobile design engineers, and the latter have no concern with adhesion to fabric which must be considered by the pneumatic tire technologists and those concerned with hose and belting. This paper is intended to deal primarily with some of the physical properties which affect the service of finished products.