ik 1, 1914.] 



THE INDIA RUBBER WORLD 



17 



What the Rubber Chemists Are Doing. 



SOME UkfERIi w WORK ON SYNTHETII RUBB] 



IN the "Journal of the American Chemical Society" (April, 

 1914), L. P. ECyriatides describes some highlj technical 



work which is oi interest to the rubber industry, as il indi 

 cites a possible method of making synthetic rubber, and 

 were it not for the high cost of the raw materials used and 



the complicated and costly pr of manufacture it might 



be of commercial value. 



The first article is entitled "« >bservations on some Barbier 

 Grignard Reactions." The reacti' >n relates to the action of 

 ethyl-magnesium bromide on \arious substance s and in this 

 case chlor-acetone was the substance acted upon. This re- 

 action produces oxides. The author has improved the original 

 method by substituting ethyl-chloride for the ethyl-bromide 

 which was used in the original Barbier Grignard process, be- 

 ing acted upon by metallic magnesium in the cold in ethereal 

 solution. The author claims that by substituting the ethyl- 

 chloride excellent results were obtained. 



The product of the reaction was methyl-butylene-oxide. 



In the following article, entitled "New Process for the 

 Preparation of Unsaturated Hydrocarbons with Conjugated 

 Double Bonds," it is revealed that these are attempts to make 

 synthetic rubber, as the "conjugated double bonds" are the 

 necessary characteristic of all the proposed raw materials. 



The sub-head of this latter article is "Pyrogenetic Decom- 

 position of Oxides." A number of experiments was tried, but 

 the successful one was the dehydration of methyl-butylene 

 oxide made by the previous process by distillation through 

 kaolin heated to 450. The reaction was carried on in a vacuum 

 with an absolute pressure of less than 1 mm. The hydro- 

 carbon (isoprene) showed a constant B. P. of 35-36. This 

 liquid was treated with a coil of sodium wire and thus poly- 

 merized according to Harries' directions. A tough product 

 was obtained which vulcanized to a product resembling 

 leather more than rubber. 



This seems to be about the only work done on synthetic 

 rubber in America. At least it is the only work the results 

 of which have been given to the public and, taken in connec- 

 tion with Patent No. 1,106,290 of August 4, 1914, and previous 

 patents No. 1.094.317. 1.094,223, 1.093.922 and 1.093,923. which 

 were granted to L. P. Kyriatides and R. B. Earle, and as- 

 signed in each case to the Hood Rubber Co., it shows at 

 least some attempts by Americans to make some progri ss 

 in a line which has been heretofore monopolized by Europe. 



PROPERTIES OF Ki BB1 R SOLUTIONS. 



W. A. Caspari has been doing extensive experimental work 

 on the osmotic properties and physical constai i caout- 



chouc solutions. This is published at length in the "Journal 

 of Chemical Society" (London) for Vugust, 1914, pp. 2141 2150. 



Mi- slates that while the osmotic pressures exerted against 

 a semi-permeable diaphragm by various colloids in aqui 

 solution have been frequently determined, their real 

 nificance is a matter of some doubt, owing particularly to 

 the usual presence of some small amount ol foreign electro 

 lytes. But when the solvent is non-ionizable matters are 

 simplified and extremely viscid solutions like caoutchouc may 

 show peculiarities of their own. 



Osmotic pressure measurements are usually for the purpose 

 of determining the molecular weight, but are more reliable 

 when the solutions approach the character of crystalloids. 

 The cryoscopic and ebulliscopic methods usually fail to meas- 

 ure osmotic quantities of colloids, but by direct measurement 

 of the pressure inside a semi-permeable septum greater 

 delicacy is obtained. 



The following figures were obtained with fresh caoutchouc 

 in benzine: 



Percentage I 'r< ssun 



in Solution M.M. Atmospheres Viscosity 



45 (H .059 



3.59 360 .030 



2.95 251 .021 



2.10 137 .1)11 3.196" 

 1.48 77 



1.01 42 374" 



Here u will be seen the osmotic rise incri i faster than 

 the concentration. The viscosity was determined by the flow 

 through the capillary tube of the Ostwald viscosimeter. On 

 deviscifying the cai by boiling thi olution for 80 



hours the following figures were obtained: 



Percentage Pressure 



in Solution M. M. Atmospheres Viscosity 



9.95 37 (Hg I .048 287" ' 



6.89 330 .028 150" 



4.11 165 .014 



2.06 71 .006 35" 



In both cases the osmotic rise seems to depend on physical 

 condition rather than the concentration. To prove this vis 

 cous solutions were put on one side, the osmometers and the 

 deviscified solutions of same strength on the other. Also, the 

 depression of freezing point in benzine solution is so small 

 as to be of little value. 



In experimenting the author used benzol and gasoline 

 (boiling point 80°-12O i for the permeable diaphragm. Cylin- 

 drical cells of white porous earthenware were found suit- 

 able; for their solution the cell pores were blocked with cold 

 vulcanized caoutchouc. This was done by soaking them in 

 10 per cent, solution of deviscified caoutchouc, placing them 

 under a vacuum to remove air. Then after a few hours' more 

 soaking they were immersed in sulphur chloride to cure. 



The osmometer was of glass, consisting of a widened part 

 with stopper like the top of a bottle cemented into the 

 earthenware cell, and a manometer tube came out the side of 

 the glass top. This whole arrangement was lowered into a 

 wide cylinder containing the outer solvent. Deresinified 

 plantation rubber was used containing about 3 per cent, 

 nitrogenous and mineral matter. 



The more viscous solutions invariably showed an osn 

 rise against the less viscous. Similar experiments were made 

 with gutta percha. Considerable speculation is indulged in 

 in accounting for the results obtained, but it appears that the 

 final conclusions were that a convergence of the molecular 

 weight values of caoutchouc towards 100.000 is indicated and 

 gutta percha is shown as 40,000. which is considerably smaller. 



SWELLING OF VU1 I VNIZED I 



F. Kirchof (KoIIoidchem Beih., 1914, 6, pp. 1-22. 

 in the Jour. Chem. Soc, August, 1914, page 633) has examined 

 the swelling of vulcanized rubber by measuring the increase 

 in weight ol thin discs ol Para after immersion in benzine, 

 n tetrachloride, carbon bi-sulphide and benzine (naphtha 

 of .74 sp. gr.). 



The results show that the maximum swelling of caoutchouc 

 decreases as the vulcanization increases. The maximum 

 swelling was attained in 24 hours. The specific influence of 

 each liquid runs parallel with the solvent power. The swell- 

 ing velocity increases slowly with the rise of temperature. 

 The relation between the extensibility and the vulcaniz 

 coefficient is similar to that existing between the sw< I 

 capacity and the degree of vulcanization. 



