Effect of Various Types of Carbon Black on Certain Physical Properties of Rubber Compounds¹

Some Properties of Carbon Black I—Adsorption

“…Two grams of c. p. diphenylguanidine are dissolved in 1 liter of ethyl alcohol (U. S. denatured formula No. 1 has been successfully used), and 50 cc. of this solution are shaken with 1 gram of the sample for 2 hours.…”

Some Observations on Carbon Black

“…Different carbon blacks have certain definite effects upon the vulcanized rubber stocks with which they are mixed. The experiments described herein may be grouped under four main heads: (1) adsorption, (2) effect of heat, (3) reaction with sulfur and zinc oxide, and (4) dispersion or rate of settling.…”

“…Spear and Moore (7) decided that adsorptive capacity and other tests on the black were not sure indications of the quality of a stock. Recently Goodwin and Park (4) have stated that "adsorption is the one property of carbon blacks that exerts the profoundest influence upon the character of a rubber mix," while Beaver and Keller (2) state that "no correlation could be found between iodine adsorption and the effect of these blacks on the rate of cure." The results of the present work are in agreement with the opinion of Goodwin and Park.…”

Surface Chemistry of Carbon Black Effect on Vulcanization of Rubber

“…Fromandi (22) determined the adsorption isotherms of various blacks for acetic acid but presented no correlation with curing properties. Beaver and Keller (8) showed definitely that blacks retard the rate of cure of rubber stocks in direct proportion to the amount of oxygen held on their surface. Johnson (28) found that, when the volatile matter of a rubber black is above a certain limit for that variety, its reenforcing effect in rubber compounds is smaller and the rate of cure of the stock is slower.…”