596 



THE INDIA RUBBER WORLD 



[August 1, 1916. 



What the Rubber Chemists Are Doing. 



VULCANIZING BY ULTRAVIOLET RAYS. 



AFREXCH chemist, H. Olivier, has perfected the following 

 method for vulcanizing rubber solutions by ultra-violet 

 rays. The rubber solution, containing free sulphur, with 

 or without certain organic or inorganic sulphides which are de- 

 composed by ultra-violet rays, such as carbon bisulphide, allyl 

 sulphide, or antimony sulphide, passes from a hopper on to an 

 endless steel band, which is carried by guide rollers round the 

 greater part of the periphery of a mercury vapor lamp. The 

 lamp is surrounded by a double, hemicylindrical water-jacket of 

 quartz, in order to cut off heat rays. The time of exposure is 

 quite short, in order to avoid the deleterious effect of prolonged 

 exposure to ultra-violet radiation on the rubber. As an example, 

 a layer of solution a fraction of a millimeter thick, at a distance 

 of 5 centimeters from the lamp, which is operated at 220 volts 

 and 3 amperes, requires an exposure of about 40 seconds. After 

 passing the lamp the soUiticn is removed from the endless band 

 to a receiving vessel by n-ejns of a scraper. 

 A ;IXG TESTS. 



C. Beadle and H. P. Stevens have tested the keeping quality 

 of vulcanized material, from rubber prepared after the manner 

 proposed by B. J. Eaton of the Department of Agriculture of 

 the Federated Malay States, who suggested the treatment of 

 rubber coagulum with caustic soda, sodium carbonate, or lime, 

 to obtain a product having a very rapid rate of cure. The result 

 of the test made by Beadle and Stevens shows that such rubber 

 when vulcanized deteriorates on keeping, and sooner or later 

 "perishes." 



A series of experiments, conducted by C. D. Kratz, on ac- 

 celerating vulcanization by increasing the temperature, leads to 

 the conclusion that if a compound is correctly vulcanized the 

 temperature at which it is vulcanized in no way affects its aging 

 properties, and the author decides that it is therefore safe to 

 increase the temperature of vulcanization (within reasonable 

 limits) for the purpose of increasing output, provided that the 

 highest temperature which may be employed corresponds with 

 the shortest time capable of definite measurement under the con- 

 ditions of vulcanization. 



PLASTIC SUBSTANCES. 



The war has necessitated the economy of such volatile 

 solvents as ethyl alcohol and ether for use in the manu- 

 facture of explosives. In 1914 Henri Barthelemy, of Paris, 

 published a study of this subject (See The India Rubber 

 World, March, 1915, page 324). In a recent issue of "Le 

 Caoutchouc & la Gutta Percha" he reverts to the subject 

 from a mathematical point of view. He finds it practicable 

 to recover at least 50 per cent of these solvents from the 

 air containing them. Two systems are available for the 

 purpose. One of these is the Claude process, which depends 

 on heat absorption by expansion of the air in molecular 

 contact with the solvents. The other is the ordinary system 

 of refrigeration by machines using ammonia or carbonic and 

 sulphuric anhydrides. 



Each method has advantages and disadvantages. The 

 Claude is simple and economical of space, with low freezing 

 efficiency, while the other system is more complicated, occu- 

 pies more space, but is more effective. 



METHODS OF ANALYSIS. 



BARIUM CARBONATE IN VULCANIZED RUBBER. 



'X'flE method of J. B. Tuttle for the determination of barium 

 ■*■ carbonate in vulcanized rubber is as follows ; One gram 

 of the rubber is placed in a porcelain boat and ignited in a cur- 

 rent of carbon dioxide in a glass tube. The residue is finely 

 ground, treated with 5 to 10 grams of ammonium carbonate, 

 IS to 20 cc. of strong ammonia, and SO cc. of water, and boiled 

 for 15 to 20 minutes, to convert lead sulphate into carbonate. 

 The insoluble matter (baritim sulphate and carbonates of lead, 

 barium, calcium and zinc) is filtered off, washed to remove 

 soluble sulphates, and treated with 10 cc. of glacial acetic acid 

 and sufficient water to make the total volume 100 cc. The solu- 

 tion is heated to boiling and filtered. Lead is removed from the 

 solution by precipitation as sulphide, and the barium then deter- 

 mined as sulphate. This gives the barium present as carbonate, 

 and the barium present in the rubber as sulphate is obtained by 

 the difference. 



The well-known French rubber chemist, Andre Dubosc, has 

 recently discovered a new process for separating pure rubber 

 from combined sulphur in reclaimings. He is said to be now 

 perfecting the industrial application of this discovery. 



CHEMICAL TREATMENT OF RUBBER. 



THE UNITED STATES. 



Producing Substances Resembling Caoutchouc. The process 

 consists in polymerizing isoprene in the presence of from 2 to 5 

 per cent of isoprene ozonide. [Henry S. A. Holt and Gerhard 

 Steinnig, assignors to Badische Anilin & Soda Fabrik, Ludwigs- 

 hafen, Germany. United States patent No. 1,189,110.] 



Process of Reclaiming Rubber. The waste rubber is heat- 

 treated with protein in the form of an albumin. [Harold B. Mur- 

 dock. Assignor to Rubber Regenerating Co., both of Naugatuck, 

 Connecticut. United States patent No. 1,189,282.] 



Reclaiming Rubber Waste. The process of reclaiming rub- 

 ber waste containing lead and sulphur by adding a reactive sub- 

 stance such as zinc sulphate, to form, with the sulphur and lead 

 respectively, a light colored water-insoluble sulphide and a light 

 colored water-insoluble lead salt, and converting the lead sulphide 

 into the said light colored sulphide, and lead salt, through the 

 action of the reactive substance (zinc sulphate). [Harold E. 

 Murdock, assignor to Rubber Regenerating Co. — both of Nauga- 

 tuck, Connecticut. United States patent No. 1,189,721.] 



THE united kingdom. 



Process and Appar.\tus for Coagul.\ting Latex. Latex 

 is supplied to tubes provided with longitudinal slots, ar- 

 ranged at top of a chamber into which a coagulating vapor or 

 gas, such as carbon dioxide or smoke, is admitted. The latex 

 flows from the slots on to a series of inclined glass or other 

 plates, arranged vertically one below the other, in such a way 

 that the uncoagulated latex from the top plate is received by the 

 second plate of the series, and so on. The plates are in parallel 

 pairs, pivoted about a horizontal shaft, so that when a layer of 

 sufficient thickness has been formed on the upper plate of a pair, 

 the pair can be rotated through 180 degrees to enable the under 

 plate to receive the latex. By this method it is possible to sep- 

 arate the rubber from a given latex into different grades or 

 qualities. [W. G. ten Honte de Lange. Jr.. Bandoery, Java, and 

 C. Bosman, Haarlem, Holland. British Patent No. 10,382 (1915).] 



THE FRENCH REPUBLIC. 



Process and .'\pparatus for Treatment of Latex. Latex 

 is placed in shallow aluminum trays (about SO by 20 

 centimeters) to a depth not exceeding 2 centimeters, and the 

 trays are packed on shelves in a chamber. A charge consists of 



