The Raman Spectrum of Rubber

Abstract

Abstract It has been previously reported that the Raman effect is exhibited by rubber as a continuous scattering together with the presence of broad bands (Franklin and Laird, Phys. Rev., 36, 147 (1930); Busse, J. Phys. Chem., 36, 2862 (1932)). Busse attributed this result to the viscosity of the solutions or to the possibility that the rubber groups respond to a wide range of frequencies. However, viscous solutions of polysterol in carbon tetrachloride give a line spectrum (Signer and Weiler, Helv. Chim. Acta, 15, 649 (1932)). As to the second explanation, this does not seem to be the nature of the Raman effect (Bär, Helv. Phys. Acta, 4, 369 (1931); Bär, Z. Physik, 79, 455 (1932)). The Raman effect has been investigated extensively for terpenes other than rubber. The bands and continuous background for rubber appear to be due to fluorescence of impurities, oxidation products, or the rubber hydrocarbon. The acetone extract of rubber is fluorescent as observed in ultra-violet light. The intensity of the bands and background for rubber decreases as the rubber is purified. However, acetone extraction and two diffusions with ethyl ether did not remove the fluorescence entirely, as could be seen by examination between complementary light filters. Some of the background is undoubtedly unmodified radiation, that is, Tyndall scattering by the colloidal structure and by motes. This can be reduced by a monochromatic light filter.