Heats of Reaction of the System Rubber-Sulfur

Abstract

Abstract PREVIOUS investigators have employed two methods for determining the heat effects when rubber is vulcanized. In one method the heats of vulcanization are found by subtracting the heats of combustion of vulcanized rubber—sulfur compounds from the heats of combustion of the corresponding mixtures of rubber and sulfur before vulcanization (1, 10, 11). This method is limited in precision by reason of the fact that the differences thus obtained are at most only a few per cent of the measured heath of combustion. The other method, which has been used previously, involves the determination of the temperature rise which occurs when mixtures of rubber and sulfur are vulcanized. This method has, for the most part, been used for relative measurements, but Blake (2) has recently employed it for quantitative determinations of the heats of reaction of rubber with proportions of sulfur up to about 8 per cent by weight. Recently Daynes (7) has employed a similar method for measurements over a wider range of composition. This investigation was undertaken for the purpose of measuring the heath of reaction of rubber with different percentages of sulfur over the entire range of composition in which combination takes place. The study was exploratory in character, the aim being to make the measurements by direct means with emphasis on simplicity rather than refinement of calorimetric procedure.