The Reënforcement of Rubber

Abstract

Abstract It is a well-known fact that, when mixed in rubber, certain powders reënforce the latter to a considerable extent, whereas others have no effect or only a relatively slight one. Since the nature of the phenomena which take place under these conditions in rubber is far from well established in the present state of knowledge, I have carried out certain experiments of a very simple kind which will by analogy throw some light on the subject. I have found that very important information can be obtained from the study of some physical properties of mixtures of different powders in organic liquids. For a beginning, ordinary paints were tested, but the presence of drying oils complicated matters and it was found advantageous to replace the linseed oil with a non-oxidizing oil, as for example, peanut oil. In this way, pastes of different concentrations were prepared, and the resistance to rupture of the films of these pastes was measured by a method often used to determine the surface tension of liquids. A convenient method of operation is as follows: two thin rods are wet with the paste and are made to adhere to one another. The upper rod A is fastened permanently in a way not shown in Fig. 1. From rod B hangs a pan for small weights which, added in convenient quantity, will finally bring about rupture of the film and separation of the two rods.