Hysteresis in the Crystallization of Stretched Vulcanized Rubber. II. X-Ray Studies of the Effects of Sulfur Content and Method of Curing

Abstract

Abstract 1. Improvements in technique make possible complete rubber patterns in only five minutes' exposure. 2. The extreme sensitivity of hysteresis in crystallization to changes in temperature at which the stock is investigated is demonstrated. 3. Hysteresis decreases with the time of cure for a given compound. 4. Crystallinity at a given elongation seems to decrease with increasing temperature of curing for equivalent cures over the range of 239–307° F. 5. For the stock studied, at a given time and temperature of cure, the proportion of sulfur giving the greatest crystallinity at 550 per cent is between one and three per cent. 6. Inhomogeneities in the disappearance of crystallinity have been clearly demonstrated, and shown to be an exaggerated localized hysteresis effect.