THE INDIA RUBBER WORLD 



I Septet 



What the Rubber Chemists are Doing. 



SYNTHESIS OF CAOUTCHOUC. 



THE Fou-owiXG ABSTRACT from the "Journal of the Society of 

 Chemical Industry," volume 38, 428A, June 30, 1919, 

 summarizes an article by H. Standinger.' In polymeriz- 

 ing isoprcne, compounds of the terpene scries are simultane- 

 ously produced, in quantities varying with the conditions of 

 polymerization, and these influence the character of the final 

 product. Synthetic preparations, although very similar to the 

 natural product, are not yet identical, as lias been shown by 

 Stemmig." 



In order to obtain a tougher synthetic rubber attempts have 

 been made to mi.x the isoprene with styrol, linseed oil, and 

 especially tung oil, but all the products are more or less 

 sticky. The ordinary inorganic and organic peroxides, such 

 as sodium peroxide and benzyol peroxide, do not accelerate 

 the polymerization to such an extent as pure oxygen, but, 

 like ozone, are used in technical processes as catalysts. The 

 varieites of rubber obtained by polymerizing butadiene and 

 dimethyl-butadiene differ in character from the isoprene 

 product, and methylcaoutchouc from dimethylbutadiene is now 

 an important synthetic product in Germany. The yield of 

 isoprene from oil of turpentine is increased by carrying out 

 the process in vacuo." By using limonene instead of oil of 

 turpentine the yield is increased from about 25 per cent to 65 

 per cent. Essential oils, however, cannot be obtained in suffi- 

 cient quantity to be practicable sources of isoprene. The produc- 

 tion of butadiene from phenol and of isoprene from cresol would 

 be too expensive, while these substances are required for other 

 purposes. Coke-oven gases are a cheaper source of benzene, and 

 synthetic rubber has been successfully prepared in Germany by 

 converting this benzene successively into cyclohexane, chlorocy- 

 clohe.xane, and tetrahydrobenzene, which, on heating, gives 

 butadiene and ethylene. The amount of butadiene and isoprene 

 in coal tar would only furnish a small fraction of the amount 

 required, while the conversion of alcohol into butadiene would 

 be too expensive, apart from the fact that the most favorable 

 conditions for the reactions have yet to be discovered. If im- 

 pure butadiene hydrocarbons are used sticky products are formed. 

 American petroleum contains at least one per cent of a mixture 

 of the three pentanes (boiling at 9, 30 and 38 degrees C.), which 

 at the present time is practically a worthless constituent of the 

 gases. About 370,000 tons per annum of these compounds would 

 be available in the United States. It has been shown by Holt^ 

 that they could be converted into isoprene, but this synthesis 

 would be practicable only in America. Acetone prepared from 

 acetylene was used in Germany during the war as the source of 

 synthetic rubber. It was reduced by means of aluminum to 

 pinacone, which was then converted into dimethyl-butadiene and 

 dimethylcaoutchouc. The plant is capable of producing about 

 two thousand tons of rubber per annum, but under normal con- 

 ditions the process would be too expensive. 



MECHANICAL COAGULATION OF RUBBER. 



.\ current of air is passed over the surface of the warm latex, 

 the temperature of which is raised either by applying heat at the 

 bottom of the vessel or by preheating the air. In order to avoid 

 the form.ation of a skin which would prevent the action of the 

 air on the deeper layers of latex, the mass is kept stirred by 

 rocking the vessel. The crepe obtained from the final coagulum 

 has a light color, and in quality appears comparable with rubber 



' "Schweiz Chemische Zeitschrift," 1919, Volume I, pages 1-5, 28-33, 60-64. 

 - "Juurnal of the Society of Chemical Industry," 1914. page 267. 

 •"Journal of the Society of Chemical Industry," 1911, page 1023. 

 ♦"Journal c! the Society of Chemical Industry," 1914, page 364. 



prepared by the customary process of coagulation with acetic 

 acid. C'.lournal of the Society of Chemical Industry," May 31, 

 1919.1 



EFFECT OF EXPOSURE TO WEATHER ON RUBBER GAS-MASK 

 FABRICS. 



.\ paper by G. St. J. Perrott and A. E. Plumb in "The Journal 

 of Industrial and Engineering Chemistry," May, 1919, pages 438- 

 443, reports the results of their investigations on the effect of 

 exposure to weather on rubber gas-mask fabrics. 



Fabrics of different manufacture and consisting of finely- 

 woven cotton sheeting covered with a rubber layer from 0.01 

 to 0.025-inch thick, deteriorated very slowly over a period of 

 100 days. There was a general relation between the amount 

 of acetone extract and the permeability, and deterioration was 

 more rapid in the summer months than in winter. Fabrics 

 exposed rubber side downwards showed no appreciable de- 

 terioration over the whole period; those exposed rubber side 

 upwards, but shielded from ultra-violet light, deteriorated at 

 about the same rate as those exposed to the direct rays of 

 the sun. There was no apparent relation between the results 

 of weather aging and an accelerated aging test at 130 de- 

 grees C. The tensile strength of all the fabrics decreased by 

 15 per cent 'during the exposure. Both the fabric and rub- 

 ber rotted when exposed to high concentrations of phosgene 

 for 15 hours. Analysis of the fabrics indicated that over 10 

 per cent of bitumen was undesirable and that as high as 20 

 per cent of carbon tended to preserve the fabric, especially 

 when exposed to direct sunlight. Fabrics with a high per- 

 centage of gum (rubber) were inore resistant than those 

 containing a large amount of filler. 



X-RAY EXAMINATIONS. 



At a joint session of the Faraday and Rontgen Societies, 

 .■\pril 29. 1919, in the rooms of the Royal Society, Burlington 

 House, London, the subject of the examination of materials by 

 X-rays was discussed from an engineering standpoint in a series 

 of papers by noted authorities. 



Quoting from abstracts of these papers' : 



It is now known for certain that X-rays are nothing but 

 ordinary light waves of very small wave length. This fact 

 explains'their extraordinary property of penetrating all sub- 

 stances, more or less, and it also follows that, generally speak- 

 ing, the smaller the wave length, the greater the penetrating 

 power. It is therefore the production of the so-called "hard" 

 rays, those of exceedingly small wave length, that principally 

 interests the engineer. But such rays require a very high 

 tension discharge to produce them, and this, coupled with 

 the hmitation which the intense local production of heat 

 places in the way of making tubes which can absorb a great 

 deal of energy, is the principal difiiculty in the way of prac- 

 tical progress. Up to the present it is hardly a workshop 

 proposition to examine more tlian an inch or two of steel 

 (although it is claimed that 4 inches have been penetrated) — 

 and even so, considerable exposure is necessary, some 250 

 seconds for 35 min., but as much as 2,000 seconds for 40 mm., 

 according to M. Pilon and Mr. Geoffrey Pearce. 



The most powerful tubes at present used require a voltage 

 of more than 100,000, and they absorb some SO kw. It is 

 therefore obvious that further progress will call for all the 

 skill and knowledge at the disposal of the physicist and 

 electrical engineer. 



S. A. Pollock, of the British Post Office, stated that for 

 the examination of soft materials like gutta percha, in which 

 impurities were often introduced, and for discovering defects 

 in the lead sheaths of underground cables, the method had 

 been found extremely useful. 



GERMAN EBONITE SUBSTITUTE. 



.\ new ebonite substitute known as "Hornite" has been intro- 

 duced by The Hornite Works Joint Stock Co., Dusseldorf, Ger- 

 many. Hornite is prepared from industrial residues and in 



Electrical Rev 



June 6, 1919, page 679. 



