Vulcanization without the Use of Sulphur

Abstract AS far back as 1915 I described the various methods of vulcanizing rubber without the use of sulphur which I was the first to discover. At the same time these researches gave rise to an international controversy in scientific circles. For reasons beyond my control I have not until now been able either to publish the results of my physical or strictly technical tests of rubbers vulcanized by my new methods, or to place numerical valuations on their physical properties. Many chemists who have repeated my experiments, of course under somewhat different conditions, often obtained results that did not coincide with mine. In consequence a number of discrepancies have gradually crept into the literature and in places even generalizations that are contrary to fact (C. Harries). Among others, B. D. Porritt claims that 1.3.5. trinitrobenzene, although a vulcanizing agent for rubber, is inactive in the absence of oxides. This statement, as will be shown subsequently, is incorrect. Moreover, some of the experimenters have come to the conclusion that the vulcanization of rubber without sulphur cannot be applied practically in the rubber industry.</jats:p

Vulcanization of Rubber. By Organic Peroxides or by Ammonium Persulphate

Abstract 1. Organic peroxides vulcanize rubber not only in the absence of sulphur but likewise without any foreign substances such as metallic oxides or accelerators of any kind. 2. Rubber vulcanized by means of an adequate amount of benzoyl peroxide (10 to 30 per cent.) gives a soft rubber product which does not differ in point of physical properties from products cured with sulphur, or rather with sulphur chloride. 3. The process of vulcanizing rubber with benzoyl Superoxide is completed in a relatively short time even at a fairly low temperature, sometimes even in two minutes at 119° C., corresponding to 13 pounds pressure. 4. Vulcanization of rubber by means of peroxides may lead to the formation of a soft, transparent and elastic product, which is almost entirely colorless. 5. The products in question vulcanized by means of various peroxides are gradually converted to a very sticky and viscous mass. 6. Sulphur protects the vulcanizates in question from such decomposition or oxidation. However, the products obtained in vulcanization of rubber with organic peroxides in the presence of sulphur are opaque. 7. As distinguished from sulphur, selenium, tellurium, their sulphides, metal oxides (in particular, lead oxide) as well as amines (aniline), tannic acid, and metallic aluminium powder not only do not protect the peroxide vulcanized rubber products from decomposition or oxidation but, on the contrary, they accelerate such processes quite considerably. 8. Benzoyl peroxide is the active vulcanizing agent in the process of heating rubber with a mixture of sulphur and benzoyl peroxide. 9. When rubber is subjected to the action of a mixture of some nitrobenzenes and benzoyl peroxides, vulcanization is effected exclusively by the nitrobenzenes, and the benzoyl peroxide remains altogether passive. 10. Ammonium persulphate vulcanizes rubber completely, resulting in a porous product which, generally speaking, is of small practical value.</jats:p

The Nature of Post-Anaphylactic State in Guinea Pigs

Summary Normal guinea pigs react to subcutaneous injection of diphenylformamidine hydrochloride by the same characteristic symptoms as those which appear in desensitized guinea pigs on the injection of chrysoidin in the post-anaphylactic state. The symptoms of the anaphylactic shock in guinea pigs in which a hydrochloric acid solution of antifebrine (acetanilide) was injected shortly before the reinjection, are expressed, as a rule, in very unusual forms. They become in this case identical with the symptoms which appear in animals in the period of post-anaphylactic state after subcutaneous injection of chrysoidin. Subcutaneous injection of some anti-shock preparations, in particular diphenylformamidine hydrochloride and di-phenylmethylpyrazolonyl, quickly and considerably increases in antimals (rabbits) the sugar content of blood.</jats:p

Post-Anaphylactic State in Guinea Pigs

Summary Sensitized guinea pigs which received on reinjection a sublethal dose of antigen and therefore survived the anaphylactic shock, are in a pathological state. As a rule, this characteristic post-anaphylactic state is easily discovered on the seventeenth day after the reinjection of the antigen. It is expressed in sharply changed reactions of animals to various chemical preparations, e.g., to azo-compounds, and in particular to chrysoidin (2.4-diaminoazobenzol). Subcutaneous injection of chrysoidin produces in these animals a peculiar reaction the symptoms of which greatly resemble those of acute anaphylactic shock in rabbits. In the post-anaphylctic state guinea pigs tolerate some chemical preparations, and in particular chrysoidin, in considerably smaller quantities than do normal animals. The post-anaphylactic state of guinea pigs changes into normal state by itself not later than thirty-one days after the shock. Timely injections of some anti-shock preparations prevent not only the anaphylactic shock, but likewise the post-anaphylactic state of guinea pigs. To these preparations belong: (a) phenylmethylpyrazolone; (b) phenyldimethylpyrazolone (antipyrine); (c) di-phenylmethylpyrazolonyl (Rossium); (d) the sodium salt of Phenyldimethylpyrazolonylaminomethylene sulphonic acid (melubrine); (e) methyloxindol; (f) alpha-phenyl-alpha-acetyl-hydrazine.</jats:p