The Action of Finely Divided Solid Substances on Elastomers

Abstract

Abstract The most important conclusions drawn from the concepts discussed can be summarized as follows: 1. The interaction between instability points of the electrostatic surface potential of fillers and the electronic structure in rubber or rubberlike substances leads—as a result of Coulomb's attraction between surface field and induced dipole moment—to at least temporary fixation of rubber molecules at the filler surface. 2. Polarization of the double bond is linked to a very slow process of molecular rearrangement. 3. The rubber molecules are constantly maintained in an unstable reactive state under the polarizing influence of the filler surface. 4. In the limiting case, double bond polarization leads to formation of new C—C linkages. The resulting high molecular compounds are closely related to the phenomenon of bound rubber. 5. The partially polarized state of the double bond is a function of the surface properties of the fillers. It has a substantial effect on the start and course of vulcanization. 6. The excitation conditions of the rubber molecules, which vary from filler to filler, appear to be the cause of the filler-specific properties of vulcanizates. To complete the picture of the interaction between filler and rubber, allowances must be made for a number of other factors. Specifically, chemical groupings at the filler surface will play their specific part in addition to the general processes, just as van der Waals' forces must not be disregarded in the adhesion of rubber molecules to the filler particles. However, the broad course of what happens in the interaction of filler and rubber seems to be determined by the processes described.