78 



THE INDIA RUBBER WORLD 



[December r, 1907. 



Total gross 5,440 'bs. 

 " tare 969 " 



" nett 4.471 " <n 3s. id £i,i55 o 2 



^% draft on £1,155 o 2 5 15 6 



£1,149 4 S 

 2}4% discount on £1,149 4 8 28 14 7 



£1,120 10 I 

 "This to form an additional rule to the rubber contract rules as 

 agreed by the London merchants and brokers and the Liverpool 

 representatives on April 18, 1901." 



THE SCIENCE OF RUBBER RECLAIMING. 



BY VV. T. BONNER. 



THE above caption possibly meets with some objection from 

 technical workers in the field of rubber research, claiming 

 that as yet no science is employed in this important department 

 of the rubber industry. Admitting that their objections may 

 to a certain extent be true, even though based upon superficial 

 grounds, the cause may be placed to lack of knowledge of the 

 structural formation of rubber itself. The lance of more than 

 one of the ''Knights of the test tube" have been broken against 

 the breast of this industrial monarch of the tropical forests in 

 their effort to wrest from its sturdy bosom the secret of its 

 "river of life"^among whom none more valiant than the 

 lamented Weber. However, much has been gained of great 

 practical value to the rubber manufacturers. 



It is not the writer's intention to enter into any discussion 

 relating to the technical side of the rubber question, but to cover 

 as well as this article will permit the subject of its re-application 

 to its field of original use and the general methods used in its 

 restoration. 



It is generally believed, even by many manufacturers of re- 

 claimed rubber, that if the "stock" could be completely "desul- 

 phurised" in their process, the resultant would approximate 

 closely in efficiency value to the original compound previous to 

 "curing." 



Science has proved conclusively that "cured" stock can be 

 completely desulphurized, but the product lacks cohesion, is dry 

 and refractory, possessing little or no value in strength, elasticity 

 or compounding efficiency, and it is of value solely as a bulking 

 and resilient filler. This feature is most pronounced in the goods 

 recovered from the purest grade of rubber goods, and is ex- 

 plained by the absence of low grade organic materials, such as 

 oils, tars, waxes, and other cheap adulterants. To utilize this 

 quality of waste as rubber, a means of fluxing had to be adopted, 

 and, so far as the writer has been able to learn, is used in all 

 methods of reclaiming at present. Such fluxes consist of oils, 

 mineral and vegetable, coal tnrs of different density, and last, but 

 most generally used, rosin oil. 



After the rubber to be treated has been finely ground and 

 placed in "pans" preparatory to being placed in the "heater," an 

 amount of the fluxing agent ranging from 5 to 20 per cent, of 

 the rubber is carefully mixed with it in the pans. Then the mass 

 is placed in the heater and direct steam ranging from 60 to 100 

 pounds per square inch is applied from 12 to 24 hours. The oil 

 is supposed to enter the rubber and soften all of it, but such is 

 not the case. The molecule of rubber has a most wonderful 

 absorbing capacity for oils, but does not chemically combine. A 

 small percentage of the rubber, not exceeding double the per- 

 centage of oil used, unite by absorption with the oil, greatly 

 adding to volume, binding together by oil saturated fibers the 

 still inert greater per cent, of "reclaimed rubber." Its ability to 

 be milled into sheets only comes from the binding qualities of 

 the oil saturated portion of the material. 



By subjecting the majority of samples of reclaimed rubber on 

 the market to-day to acetone and removing all fluxing material 

 the rubber becomes a dry powdery mass, possessing but little 

 additional value to its state before reclaiming. That the rubber 



so saturated with oil has a value is of course without question, 

 but it is also true that if some means of constant agitation could 

 be used during the process of reclaiming, the value of the shoddy 

 would almost be doubled. 



After the fact becomes apparent that even if "cured" rubber 

 can be perfectly desulphurized and yet not assume its former 

 proportions, the researcher naturally asks "What has happened 

 to the rubber by its temporary association with sulphur?" The 

 writer will not advance a theory of vulcanization, feeling that he 

 has a good one. But the fact remains that, in spite of de- 

 sulphurizing, unless a flux is used the reclaimed rubber is dry 

 and refractory to rubber requirements. 



Rubber has been placed by the men of science under the roof 

 tree of that great family known as hydrocarbons, whose lines, 

 however, are as plainly drawn as "Mendilejeff's Table of Ele- 

 ments," ranging from anthracite coal to natural gas, embracing 

 comprehensively the whole field, yet yielding none bearing the 

 least physical semblance to their adopted relative. 



In summing up the work done by the writer, together with 

 some practical tests included, the following deductions are drawn : 

 That the absorption and permanent retention of hydrogen by 

 sulphur from the many complex bodies forming the structural 

 part of rubber leaves the rubber after desulphurizing in a dry 

 and refractory state. Consequently the problem involved is to 

 restore synthetically a sufficient quantity of hydrogen chemically 

 combined with the rubber, and restore it as nearly as possible 

 to its former crude condition, and proving its permanency by 

 the acetone test. 



The writer has succeeded in accomplishing nearly all of the 

 above requirements, as well as "recovering" the stock twice over, 

 with an efficiency double any other products examined. He hopes 

 to give further and complete details in another paper. Appended 

 is a simple series of practical tests that ought to be of service 

 to the reclaiiuer of rubber in his daily business. 



For comparing the value of recovered rubber as against the 

 original product by any process for reclaiming : 



First. Compound any given quantity of rubber with usual 

 ingredients to obtain a product of a certain desired standard of 

 efficiency. After curing, submit product to the tests required, 

 making careful note of the same for a record of comparison. 



Second. After completing tests as above, reduce the product 

 to powdered form suitable for devulcanizing or reclaiming, as is 

 required in all processes. After reclaiming, dry and "mill" the 

 stock as in the usual manner. 



Third. Make of the recovered goods, without addition except 

 sufficient sulphur, the same product or object as first made, and 

 cure as usual. Then submit the finished product to the tests as 

 used in the first finished material. The difference in the standards 

 of the original and the recovered is the percentage of efficiency 

 by comparison between the original and the recovered products, 

 provided a proper cure has been effected. 



The above is an extremely simple method by which any process 

 of reclaiming rubber can be kept to its highest point of efficiency, 

 while the test can be farther advanced by repeating the operation 

 upon the same product as many removes as desired. 



Tires and Sewing Thre,\d.— The increased price of spool 

 cotton is now blamed on the automobiles. .\t least, the explana- 

 tion, according to one man identified with the spool cotton busi- 

 ness, lies in the fact that a big part of the cotton most suitable 

 for thread manufacture now goes into the making of automobile 

 tires, the demands of the latter having greatly raised the prices 

 to the thread people. 



The .Vnglo-Malay Rubber Co., Limited, announce an interim 

 dividend of 10 per cent. The entire dividend last year was 18 

 per cent. Recent quotations, £5 17^. 6d. to £6 for fully paid £1 

 shares. 



