The Gel Phase in Natural Rubber

Abstract

Abstract Evidence is presented which suggests that the true gel phase in natural rubber is composed of small crosslinked latex particles (microgel), whose presence is revealed by light scattering and by electron microscopy. These are combined into a matrix with soluble rubber molecules, forming the apparent gel phase. The rate of solution (and hence the apparent gel content) of this phase varies with solvent and is governed by the diffusion rate of solvent into rubber. Prolonged extraction removes the soluble component. Since the redissolution of the soluble component is very rapid, it is inferred that it is initially bound to the microgel particles by specific forces which have to be overcome by the diffusing solvent. Mastication of crepe breaks up the matrix, leaving microgel particles whose presence can be detected in solution.