The Nature of the Particle Surface in Hevea Latex and Pastes of Rubber Hydrochloride and Polyvinyl Chloride

Abstract

Abstract The colloid-chemical properties of natural rubber latex are influenced by many factors, such as the pH, the concentration of surface-active agents and the presence of ions of different kinds. Many of these factors have been studied intensively. However, it has usually been assumed that the surface of the rubber particles consists of plain hydrocarbon. Up to now it has been impossible to investigate the properties of the surface free from adsorbed soaps and proteins, for the removal of these surface-active agents results in coagulation of the latex. But the latex particles can be obtained in a hard and nontacky form by hydrochlorination and crystallization according to the methods of van Veersen and the author. The various surface-active agents can then be removed by filtering, washing, and extraction with organic solvents, without the loss of the surface by coagulation of the particles. The reactions of most organic chemical groups with hydrochloric acid are fairly well known and, though the original properties of the surface may be modified to some extent by the hydrochlorination, an investigation of the surface of rubber hydrochloride may give useful information regarding the properties of the original surface of the rubber particles. A suitable method for studying the nature of the surfaces of various rubber hydrochlorides would be to investigate the rheological properties of concentrated dispersions in organic media. Dispersions in plasticizers were selected, in the first place, because the experimental work is then not complicated by the volatility of the solvents, and secondly, because these dispersions in plasticizers are of some technical interest, since they can be used for the preparation of monofilaments from rubber hydrochloride.