October 1, 1920.] 



THE INDIA RUBBER WORLD 



cord cannot stand the minimum pull it is not fit for Uncle Sam's 

 use. 



In (jnlcr to test tlie cord tlioroughly, samples are cut from 

 each 500 feet of the product unless the inspector judges that the 

 uniformity of the cord can be ascertained with fewer samples. 



.^s almost all resilient material deteriorates with age, great care 

 is taken to use new elastic cord, no ct)r(l licinc used if more than 



Elastic Coru for .'KiRrL.xxEs 



six months from the factory. To eliminate any old material, 

 each factory making elastic cord for Government airplanes is re- 

 quired to use an identification system by means of two colored 

 threads woven in the entire length of the cord. These colors are 

 designated by the Government for use in a specified period. For 

 instance, all clastic cord w'oven for the Government in January, 

 February, and March, 1920, contained threads of black and ma- 

 roon in its outer covering. 



In addition to this color system each roll of finished cord is 

 plainly marked with the date of manufacture on a tag of perrna- 

 nent nature fixed to the cord. 



The Air Service reserves the right of free access to all parts 

 of the plants in which elastic cord is manufactured for the Gov- 

 ernment, and also the right to inspect all materials entering into 

 its construction. 



We are indebted for the information used in this article to the 

 Specifications and Standards Section, Engineering Division, Air 

 Service. United States Army, Dayton, Ohio. 



MEETING OF THE RUBBER DIVISION OF THE 

 AMERICAN CHEMICAL SOCIETY 



AT the recent Chicago convention of the American Chemical 

 Society, held September 7-10, the Rubber Division had a 

 inost interesting meeting. The various divisional meetings con- 

 vened at the University of Chicago and were very well attended, 

 attendance varying between 75 and 100. The following is an 

 outline of the proceedings. 



ACCELERATORS 



Concerning accelerators, the secretary reported that following 

 the discussion at the spring meeting in St. Louis he had given 

 the announcement to the trade journals that the division did 

 not object to the proper use of trade names for accelerators, but 

 that it did most strenuously object to the marketing of unknown 

 products which are sold under trade names and whose true con- 

 stituents are supposed to be kept secret. This objection is two- 

 fold; the Division believes that the advancement of the industry 

 is retarded by the use of unknown materials and that the public 

 often suflfers by the indiscreet use of unknown accelerators. 



Discussion followed as to the best means of ridding the mar- 

 ket of vague accelerators, and a committee was appointed con- 

 sisting of J. B. Tuttle, VV. F. Zimmerli, C. W. Bedford and A. H. 

 Smith to index all available information concerning the analysis 

 of accelerators on the market and to keep this file complete as 

 new accelerators appear. The information in this file will be 

 available to members of the Division. 



PHYSICAL TESTING 



Professor H. E. Simmons reported that the committee on phys- 

 ical testing was endeavoring to obtain specifications for the phys- 

 ical testing of rubber which would be satisfactory to all of the 

 various interested societies and organizations. 



Two papers were read by Mr. De Pew, presented by the re- 

 search laboratories of the New Jersey Zinc Co. The abstracts 

 follow : 



The Aging of Some Rubrer Compounds. — Comparative re- 

 sults on accelerated aging tests on zinc oxide stocks as com- 

 pared with some carbon black stocks. Considerable checking 

 and cracking was observed on the surface of the stocks, 

 the zinc oxide stock showing up by far the more favorable of 

 the two. It was pointed out by Mr. North that the high per- 

 centage of hexamcthylene tetramine would cause very bad aging 

 and might he lield accountable for some of the bad aging of the 

 black stock. 



Some Micro-Sections Cut From Vulcanized Rubber Ar- 

 ticles. — Mr. De Pew gave a very interesting description of the 

 difficulties encountered in making microphotographs of rubber 

 articles and told of the methods with which they had been most 

 successful. He had prepared slides from a good many sections, 

 which proved quite instructive on the screen. 



peachey's vulcanization process 



The round table discussion largely concerned the method of 

 vulcanization recently proposed by Mr. Peachey. Samples were 

 shown of various types of rubber goods vulcanized by the new 

 process. The discussion brought out the following points : 



Scientifically the method is correct; the action of hydrogen- 

 sulphide and sulphur dioxide in the rubber reacting' to produce 

 active sulphur, which in turn vulcanizes the rubber almost in- 

 stantaneously at ordinary temperatures. This vulcanization per- 

 mits the use in rubber goods of many dyes which will not stand 

 the present conditions of manufacture. 



The reaction between hydrogen sulphide and sulphur dioxide 

 does not produce all active sulphur, however, a considerable por- 

 tion of sulphur mu being formed. Extraction of goods cured by 

 this process will often show more uncombined than combined 

 sulphur and the free sulphur content is usually as high as in 

 goods cured in the ordinary way. 



The practical operation of the method is the insurmountable 

 difficulty of the process. The degree of vulcanization must be 

 regulated by a very careful measure of the quantity of gases ab- 

 sorbed, the production of a uniform state of vulcanization 

 through an article of appreciable thickness being impossible. 



Because of the impossibility of obtaining a uniform state of 

 vulcanization and of the difficulty of controlling the quantity of 

 the different gases, American chemists have not grown enthusi- 

 astic over the process as have their English brothers. 



RUBBER ENERGY 



W. B. Wiegand brought out many interesting facts concerning 

 the resultant energy storage capacity of rubber compounds, their 

 hysteresis losses and other physical properties due to the intro- 

 duction of different fillers into the compound. The particle sizes 

 of ordinary compounding ingredients were shown by slides and 

 the properties they impart to rubber were shown by stress-strain 

 curves. 



The quality of the tire which enables it to stand the rough 

 usage of thousands of miles of travel, as Dr. Wiegand outlined, 

 is due to the fact that well-vulcanized rubber has several hun- 

 dred times greater energy storage capacity than any other struc- 

 tural material. This property renders it of the greatest value 

 in the absorption of the shocks of the main traveled road. Its 

 energy can be changed into frictional heat, and it can also be 

 increased by adding to it certain substances. 



"In a pncmnatic tire," said Dr. Wiegand, "the most important 

 energy losses are those due to fabric chafing. For the measure- 

 ment of these and also for the analysis of the casing from the 

 standpoint of determining the effect of various physical changes 

 upon the subs'ance, the tire pendulum is described. It shows 

 that the lessening of energy by the complete tread and breaker of 

 a pneumatic tire is no greater than that caused by a single ply 



