THE INDIA RUBBER WORLD 



[OcTeBER 1, 1920. 



of carcass fabric. The tire pendulum also shows that cord fabric 

 is three times as efficient as square woven fabric from the stand- 

 point of energy dissipation." 



Dr. Wiegand maintained that cnergj' storage capacity was the 

 only accurate measure of the ability of a tire to withstand the 

 grinding wear of the highway. He told of the effect of various 

 pigments used in the coloring of the rubber, and classified them 

 as active, or inert, in accordance with their influence in in- 

 creasing or decreasing the total energy capacity of the com- 

 pounds employed. 



The speaker also made brief reference to the probable special 

 arrangement of ingredients, when added in various proportions 

 to the elastic gum. 



SYMPOSIUM ON RUBBER ANALYSIS 



The symposium on rubber analysis was primarily intended to 

 review the work that has been done and to correlate it with any 

 work that might be attempted by the Division. W. W. Evans 

 has prepared a compilation of the literature on rubber analysis 

 which is undoubtedly as complete as anjthing published. Not 

 only are the references given but comprehensive abstracts are 

 included. The members of the Division received these before 

 the meeting so that they could be reviewed. 



Discussion on various determinations was led largely by men 

 who have been active in developing or improving these methods. 

 The various direct methods for the determination of rubber were 

 discussed and also the methods for the determination of the 

 various extracts, free and total sulphur, fillers, etc. The point 

 was brought out very clearly that since compounded rubber 

 goods contain almost anything, the production of a uniform pro- 

 cedure for the analysis of all goods was out of question. After. 

 all, the important part of rubber analysis is not to get the an- 

 alytical results, but to interpret properly the figures obtained, 

 taking into consideration the methods that were employed. The 

 division decided that for the present no work on analysis should 

 be undertaken by the Division. 



RUBBER DIVISION OFFICERS 



The election of officers for the coming year resulted as follows : 

 W. W. Evans, chairman; C. W. Sanderson, vice chairman; Ar- 

 nold H. Smith, secretary, the Research Laboratory, Goodyear 

 Tire & Rubber Co., Akron, Ohio. 



Executive Committee— G. D. Kratz, J. B. Tuttle, C. W. Bed- 

 ford, J. R. MacGregor and H. E. Simmons. 



ABSTRACTS OF PAPERS READ AT THE MEETING 



A Theory of Vulcamzation, Based on the Formation of Polysulphides 



During Vulcanization 



All organic accelerators and a number of inorganic accelera- 

 tors function as catalysts of vulcanization through the formation 

 of polysulphides. These accelerators may be placed in two 

 classes : 



1. Hydrogen sulphide polysulphide accelerators. 



Organic bases are believed to form polysulphides by the 

 aid of hydrogen sulphide. Examples are piperidene and 

 dimethylamine, which form polysulphides in the presence 

 of hydrogen sulphide and sulphur. Inorganic bases such 

 as sodium hydroxide, calcium hydrate, magnesium oxide 

 and basic magnesium carbonate function in the same man- 

 ner as the above. 



2. Carbo-sulpb-hydrol polysulphide accelerators. 



Thioureas and dithiocarbamates are believed to form 

 some type of polysulphides thrc'igh the grouping C-SH. 



Differentiated from the above two classes of accelerators are 

 such accelerators as zinc oxide and litharge, which do not form 

 polysulphides. These arc termed "secondary accelerators" owing 

 to the fact that they decompose polysulphides to give active 

 sulphur.— Winfield Scott and C. W. Bedford. 



The Action of Heat and Light on Vulcanized Rubber 



The action of heat and light on vulcanized rubber is frequently 

 spoken of as being identical, and oxidation is said to be the 

 cause of the deterioration. From published and unpublished 

 tests it is shown thai the action of heat is one of change in the 

 rate of the chemical reaction between rubber and sulphur and 

 goes on throughout the entire mass, whereas the action of light 

 is one of oxidation, taking place on the surface. Heat produces 

 no change in the solubility of tne rubber substance in solvents 

 such as acetone and alcohol, whereas light breaks up the rubber 

 molecule, forming decomposition pioducts which are readily solu- 

 ble in acetone. — J. B. Tuttle. 



The Action of Certain Organic Accelerators in the Vulcanization 

 of Rubber (II)> 



The activities of certain synthetic, nitrogenous organic accele- 

 rators, in a mixture of rubber and sulphur, were compared with 

 the dissociation constants of the original substances. With the 

 exception of members of a closely related series, no definite rela- 

 tion was found to exist between the activities of the substances 

 as accelerators and their dissociation constants. Substances 

 which decompose or react with other components of the mixture 

 to form substances of acid character do not accelerate unless a 

 neutralizing base or salt is present. The results obtained and 

 the conclusions drawn from them, compare favorably with other 

 results obtained with ammonium salts. — G. D. Kratz, A. H. 

 Flower and B. J. Shapiro. 



The Action of Certain Organic Accelerators in the Vulcanization 

 of Rubber (III)i 



The relative activities of molecularly equivalent amounts of 

 aniline and diphcnylthiourea in the acceleration of vulcanization 

 were compared in rubber-sulphur mixtures and in mixtures 

 which contained zinc oxide. In a rubber-sulphur mixture, the 

 activity of aniline was found to be much greater than that of 

 diphcnylthiourea. In mixtures which contained zinc oxide, the 

 reverse was true. With aniline as the accelerator, either in the 

 presence or absence of zinc oxide, the same maximum tensile 

 strength was obtained, accompanied by a higher sulphur coef- 

 ficient in the absence of zinc oxide than when this substance 

 was present. The mixture which contained zinc oxide attained 

 the same maximum tensile strengths at approximately the same 

 sulphur coefiicients, irrespective of whether aniline or diphenyl- 

 thiourea was employed as the accelerator. It is evident that 

 there is apparently no general relation between the physical 

 properties and sulphur coefficients of accelerated mixtures. — G. 

 D. Kratz, A. H. Flower and. B. J. Shapiro. 



The Organization of an Informatian Service in Connection With Industrial 

 Research Organizations 



The expansion of industrial research justifies a study of its 

 organization and its relation to the parent corporation. It is 

 developed that about 2 per cent of the total turnover of a cor- 

 poration may profitably be spent for development, and that 

 about 2 per cent of this development fund may be applied to in- 

 formation service. 



This department should have as large a library as is justified, 

 and, through weekly bulletins and monographs, should keep the 

 workers informed of the progress of knowledge as developed in 

 the literature and from experimental work. All the informa- 

 tion available should be indexed in such a way that it may be 

 readily searched. It seems desirable that this department should 

 edit technical reports, in order that the relation between new 

 work and old may be brought out. This department should be 

 able to prepare reports which are intelligible to business execu- 

 tives. 



The technical details of the establishment and operation of 

 such a division are discussed. — R. P. Rose and J. H. Reel. 



'Part I, see The India Rubber World. October 1. 1919, page 21. 

 »lso The India Rubber World, June 1, 1919, pages 485-6. 



See 



