The data indicates that dispersing sulfur permits the reduction of the amount used without sacrificing state of cure. With this reduction, heat aging is significantly improved. Even at the higher levels, heat aging is better if the sulfur is dispersed. There is some indication that the use of dispersions may give the compounder more latitude in time of cure which would reduce the trouble of over curing by making vulcanization time less critical. In general, there is evidence that pre-dispersing active rubber compounding chemicals changes their characteristics. It makes them more active or efficient but never the less safer to use. With the trend towards faster production, pre-dispersion offers better control in the factory. We cannot change the wettability of the base polymers to make up for the shorter milling cycle but we can employ dispersions to compensate. The additional cost of the dispersion may be balanced by better quality, saving of master batching, saving in milling time and less scrap. When Automation arrives, combination accelerations pre-dispersed will be essential. Author
Annual Symposium on Technical Progress in Communication Wires and Cables (6th) at Asbury Park, N. J., 3-5 Dec 57.