Abstract
1. Equal weights of a mixture of hexamethylenetetramine and mercaptobenzothiazole give the optimum accelerating activity and minimized scorching. 2. Scorching tests indicate that there should be no danger of scorching in practice; a comparison of the scorching tendencies of various proportions showed that a ratio of mercaptobenzothiazole 70 and hexamethylenetetramine 30 gives noticeable scorching. 3. The melting point curves, indicate some relation between the above proportion and the scorching phenomenon. 4. The heating curves of two sets of mixtures containing hexamethylenetetramine and sulfur, and hexamethylenetetramine, mercaptobenzothiazole and sulfur, respectively, in an oil bath at 150°, indicate that hexamethylenetetramine and sulfur react exothermically and that this reaction is accelerated by the presence of mercaptobenzothiazole. 5. The products of the reaction between hexamethylenetetramine and sulfur are carbon disulfide, ammonium thiocyanate, hydrogen sulfide, and ammonia. 6. The products of the reaction of two sets of samples heated in an oil bath at 150°, as indicated in 4, were determined quantitatively, and it was found that there was an increase of these products with an increase of time; which was also indicated by the loss of weight during the heating. 7. All of these reaction products had low accelerating power. Thiuram disulfide and ammonium thiocarbamate derived from carbon disulfide and ammonia and ammonium polysulfide derived from hydrogen sulfide, ammonium, and sulfur were tested, since they might have been formed during vulcanization, but they were found to be poor accelerators. 8. A preliminary test of combinations of mercaptobenzothiazole with ammonia, ammonium polysulfide, ammonium thiocyanate, and ammonium dithiocarbamate indicated that ammonia and ammonium polysulfide have some accelerating power, whereas all others are ineffective. 9. The combined use of ammonia and mercaptobenzothiazole forms a molecular compound which is effective as an accelerator, and this is true in an analogous way of the combined use of hexamethylenetetramine and mercaptobenzothiazole. 10. In order to prove experimentally the above theory, an attempt was made to treat a mixture of rubber, mercaptobenzothiazole, zinc oxide and sulfur with ammonia until the latter penetrated throughly the sample, after which the latter was vulcanized. Such treatment gives far better acceleration than does mercaptobenzothiazole without treatment with ammonia. 11. The accelerating power of ammonium polysulfide and mercaptobenzothiazole is attributed to the formation of ammonia from ammonium polysulfide and the reaction of ammonia and mercaptobenzothiazole.
The Synergistic Effect of Temperature and Loading Rate on Deformation for Thermoplastic Fiber Metal Laminates
