MODERN LABORATORIES
Rubber Laboratory of lnrtituto A g r o n h i c o do Norto
N e w Brazilian Rubber Laboratory in the Amazon N O R M A N BEKKEDAHL'
AND
FREDRICK
Valley
L. D O W N S * , lnrtltvto A g r o n h i c o do Norte, Bel6m do Par& Brazil
AT
T H E mouth of the Amaeon Valley, in the city of B e l h do Par& the Instituto Aqrondmico do Norte wm est& lished in 1941by a decree of President Vargss. It is one of seven such institutions being net up in various sections of the country by the Brazilian Government for the purpose of studying its agricultural products. Since the one located in B e l h is situated within the rubber-growing area of South America, one of its more important problems is the study of rubber from its various angles, such as the botanical, economic, and also technological viewpoints. I n the Amazon Valley there are many different types of trees and shrubs which yield a letex of one form or another. Most of these latices ptoduce rubberlike substances, varying greatly in both quality and quantity. The I.A.N., therefore, noted the need for a Ruhher Laboratory which would have for its immediate and chief purpose the evaluation of all of these types of ruhher and the subsequent recommendation of specific U S ~ Sfor each kind. New uses could also undoubtedly be found for many of those having unusual properties. I n order to make a thorough study of the technological prohlems connected with rubber, the I.A.N. planned t,o set up a wellequipped lahoratory capable of conducting all necessary tests and research on ruhher and lateu. However, there were Some difficulties. Since none of the laboratory apparatus and m e chinery needed was manufactured in Brazil, it was necessary to purchase from some foreign country. War conditions complicated matters rtnd slowed up the process of equipping the lahorsi tory. However, since the United States of America was greatly interested in procuring rubber from South America, the Brazilian Government appealed to the Government of the United States of America for assistance in obtaining purchase priorities and shipping space, and in installing the apparatus after its arrival a t the I.A.N. An agreement was made between the two governments in nhich the two authors of this paper were loaned t,a the I.A.X. for On loan t o the Institnto Agronbmioo do Norte during 1943 and 1944 from the National Bureau of Standards, Washington. D. C. On loan t o the Instituto Agrodmico do Norte during 1943 and 1944 from the AmerioanSteeland Wire Co.. Worcester, hlsrs.
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I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
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Vol. 17, No. 7
Floor Plan of Laboratory
built boilerhouse very close to the Rubber Laboratory. It produces a working steam pressure up to 100 pounds per square inch. The Rubber Lahoratory consists of a reception hall, a n office, an air-conditioned room, two washrooms, two storerooms, two chemical laboratory rooms, a n a m l y t i d halanee mom, a washing and compounding room, a ruhher drying room, a vulcanizing room, and a testing room. The diagram of the floor plan of the building indicates the position of the rooms and the location of the larger pieces of apparatus, machinery, and furniture. The smaller pieces of apparatus, such as the water still, hot plates, etc., which are set on top of the laboratory benches, are not indicated on the drawing. The plan is drawn t o scale, the length of the building being 133 feet. The veranda surrounds the building and adds another 6 feet on each side. The total floor space is more than 5000 square feet, which is ample for the laboratory and occasions no crowding of either machinery or personnel. The main entrance leads into a large reception hall, in the front part of which are a conference table and the secretary’s desk, At one side is an exhibit table on which are located samples of different kinds of Amazonian rubber, tapping knives, latex cups, and other articles of interest. Lookers for the personnel of tbhe laboratory are also located in this room. Directly hack from
Right.
Below.
Mixing
Mill and Washer
Bench in Center 01 Chemical
Room No. 1
the entrance is the office of the chief and the assistant chief of the Rubber Laboratory. This office is equipped with two deeks, two file cabinets, two bookcases, and a safe. Because of the extremely high humidity (usually over 90%) a t the mouth of the Amazon, i t was necessary to air-condition one room for experiments which cannot be performed satirfactorily under conditions of high humidity. For this purpose a small room without windows was used, its ceiling was lowered t o 8 feet in order to reduce the quantity of air to he conditioned, and a double door was placed a t the entrance. The cooling apparatus for condensing the excess moisture is a one-borsepoaer, water-cooled unit. I n this air-conditioned room are kept the pH meter, the potentiometer and its accessories, and all the laboratory’s optical instruments such as the microscopes, cameras, refractometer, etc. Experiments in which low voltages are measured, as is the case with a potentiometer, are conducted in this room, since electrial leaks with resulting errors are caused by high humidity. It was also found necessary to keep all compound optical lenses a t a reduced humidity; otherwise a fungus grows between the sections of the lenses where they are c e mented together. Thc balance room, nhich is located next to the chemical labora-
J4Yr
1945
ANALYTICAL EDITION
tory, contains three analyticd balances which are capable of weighing to within 0.1 mg. In addition to the balances and their bench, the room contains three desks for the laboratory technicians. Two rooms are equipped for the chemical analysis and research on rubber and latex. Together they contain 375 square feet of tiled bench top, in-
and glassware which are in constant use. U on the benches are located two balances and a scale of various Agrees of sensitivity and capacity, several hot plates, mechanical stirring apparatus, acetone extraction assembly, Westphal balance, water-distillation apparatus, and wringer rolls for sheeting coagulated rubber. A 3 X 6 foot hood which is equipped with water, gas, and &etricity is located in one corner of the room. A cream separator especially designed for latex is used for the concentration of latIces. Chemical Room 2 contains two drying ovens, a muffle furnace, a constant-temperature bath, a laboratory centrifuge, a refrigerator, and n cabinet for chemical apparatus, as weli as a rack for air-drying small sample sheets of coagulated rubber previous to oven-drying. The compounding and washing room contains about 140 square feet of laboratory benches under which are builtin bins and shelves which hold the compounding ingredients. On top of the benches are a number of 5-gallon tins which contain the compounding ingredients most frequently used. The room has several balances, the most sensitive being capable of weighing to the nearest 0.01 gram, and the largest having a c&pacity of 10 kg. A workbench equpped with a fairly complete set of tool., fits against one wall of the room. There is also a rack on whioh to dry the rubber crepe after it comes from the washing mill. The mixing mill is of the latest typt 6 X 12 inch Iaboratorysize, operated by a 5-horsepower helical-geared electric motor. It is equipped with a magnetic starting switch, and also with a magnetic disk brake operated by overhead levers. The rolls me cooled internally by passing water through them. The mill is
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which is about 2 inches wide, is filled'with sand and covered wit6
a separate 5-horsepower motor, and% installed in the iame manner as the mill. The vulcanizing room is large, and hesidee the vulcanieing apparatus and accessories i t contains a Banbury mixer, a BakerPerkins mixer, aging bombs, arbor press, abrader, and buffer. The vulcanizing press is B 2-opening, 4bolt press, with 20 X 20 X 1.5inehsteelplrstens. Ithasal2-inchramwithastrokeof 16 inches. The ram is operated by water pressure obtained from two hand pumps, one for closing the press and the other for producing the high pressures, 1000 pounds per square inch generally being used. An ."accumulator" of heavy spring type which is connected with the water chamber of the press helps to hold a constant pressure. The heat for the platens is supplied by steam, whiob passes to and from them through swing joints. The steam pressure is kept constant by means of B control valve operated by air pressure supplied by an electrically driven oompressor and tank. The horizontal open-ateam vulcanizer is n 20 X 36 inch jaoketed autoclave fitted with B hinged quiok-opening door. It is suitable for either open-steam or dry vulcanizations, and is built to withstand pressures up to 150 pounds per square inch. Its steam pressure is also controlled by an automatic valve like the one used on the press. Since these vulcanizers have separate controls they o m be operated independently of one another. Directly) in front of these vulcanizers is a table with a sheet-iron top, 3 x 8 feet, upon which are placed the hot molds or other products from the vulcanizers. Two cabinets. have been constructed for metal tmvs in which the comDounded batches of rubber me kept beforebdoanization. The Banbury mixer is the laboratory Size B which has a cspacity of 0.5 gallon in the chamber, and can handle about 2 Dounds of crude rubber. It is driven bv a 7.5-horse~ower re;ersible electric motor controlled by magnetic switches. This mixer is jacketed for steam heating, and its rotors are connected to the water supply for internal cooling.
Vulcanizing Apparatus
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I N B U S T R I A L A N DLEN G I N E JCR I N G C H E M I S T R Y
Vol. 17, No. 1
Compression-set tests of vulcanized rubber are made in an apparatus which compresses the rubber sample under a constant load exerted bv a calibrated mrine. The Dereentaee of camDression set ismeasured after \he kwnple i n d app&tUs h m e
compressed knder a dead-wiight load at an elevated temperitwe, and the rate of change of thickness is observed. This latter test is generally used for control purposes during the milling or oompounding operations.
Factory for Procerring Latex
The Baker-Perkins mixer is of lahoratory siae and has a working capacity of 2.25 gallons. It can he used for mixing fairly heavy pastes and plastic masses, and is especially useful for
drain the contents without stopping the blades of the mixer. It is also jacketed and connected t o the steam line for heating. Both mixers are installed on strong concrete bases separated from the concrete floor in the same manner as the mixing and washing ... mills. The laboratory has both the oven and the bomb type8 of ac-
The extremely high ceilings in the laboratory building permitted the construction of additional moms above the air-conditioned room and the washroom next to it. One of these was mrtdeinto storeroom for chemical supplies, and the other a drying room for rubber crepe. The latter room is heated electrically, and vents near the bottom and the top of the roomare controlled so as to allow the hot saturated air to escape and fresh air to enter. The Rubber Laboratory directs the operation of B small sheetrubber factory located a few miles distant in the jungles where rubber trees are more abundant. The factory is well equipped to coagulate latex by any of the chemical or smoking methods, and i t processes an average of more than 100 liters of latex each day. Barrels are used for holding the latex during the mixing and diluting operations. Pans of either wood or metal are used during coagulation by chemical or natural processes. Wringer rolls and marking rolls squeeze the water from the coagulum and form the ribbed smoked sheets. A smokehouse takes care of the smoking and drying of these sheets. Near the factory are a number of small individual smoke huts in which latex is coagulated by smoking i t on sticks or paddles. This factory, including the smoke huts, serves as a pilot plant for the Rubber Laboratory, performing experiments on the coagulation of latex on a larger Bcde than can he dohe in the laboratory. It also produces much of the rubber on which are conducted the tests and research of the Rubber Laboratory. The rubber-producing trees in the vicinity of the factory are tapped to the fullest extent at all times, and the rubber which is not needed for experimental purposes is placed on the market. LIBRARY
measure; the distance traveled. ’ The stress-strain relationships for rubber are measured in a Scott tensile tester No. L-6. This machine is a vertical-type tester. driven bv a motor. and eaniDDed with a comDens&tine head and sparkiecorder. ‘It has a c&city of 150 poinds. ana
machine lare D$evio&ly huffed t o uniform^ thickness in the
means of standard dies in an arbor piess. ‘The thickness of thk speoimens is measured by d i d gages gradusied in thousandths of an inch. The apparatus for the measurement of permanent set is comy e d of 10 units, each of which holds a small rubber strip. hese strips are cut, by means of a special die, from the same sheet from which the tensile test specimens are taken. Fatigue tests on rubber are made in a De Mattia-type flexing machine, which uses test specimens of molded strips, 1 X 0.25 X 6 inches, with a semicircular transverse groove, 0.125 inch in diameter, across the middle. A motor causes the samples to be fiexed a t a rate of about 475 strokes per minute. A counter records the number of flexes, and the operation is continued until cracking or failure occurs in the groove. Hardness measurements on ruhbcr can be made a t the laboratory by means of the Shore durometer, which gives arbitrary numerical values ranging from 0 to 100, depending on the amount of indentation of a blunt pin operating under pressure from a spring. Hardness can also he measured by moans of the Pusey and Jones plastometer, in which a dead weight is used to apply the indenting force.
One very important feature of the Rubber Laboratory is its excellent library. The I.A.N. has a large collection of books and journals related to all scientific phases of agriculture, such as botany, biology, entomology, genetics, bacteriology, zoology, chemistry, and physics. On the subjects of the chemistry, physics, and technology of rubber and latex, the library is very complete. The journals on rubber include Rubber Chemistry and Technology, Summary of Current Literature and Abstract8 of the Research Association of British Rubber Manufacturers, Transactions of the Institution of the Rubbe? Industry, Journal of the Rubber Research Institute of Malaya, India Rubber World, Rubber Age (N. Y . ) ,Rubber Age (London), and others. Each of the first four is complete from Volume 1 to the latest issue; the other sets are as yet incomplete, For other journals also important to the rubber laboratory, the library has complete sets of INDUSTRIAL AND ENGINEERING CHEMISTRY, both the INDUSTRIAL EDITION and the ANALYTICAL EDITION;Journal of the American Chemical Society; Chemical Abstracts; JouTnal of Organic Chemistry; Chemical Reviews; Journal of the Association of Ofiial Agmcultural Chemists; Journal of Research of the National Bureau of Standads; Journal of BiochemistTy; Soil Science; and others. also has the Journal of the Chemical Society (London) from 1888 to 1942. There are many important sets of books, such as Beilstein’s “Organische Chemie”, Landolt-Bdrnstein’s “Physikalisch-Chemische Tabellen”, and “International Critical Tahles”. This excellent library, cont.inuingto be enlarged considerably, is a strong asset to the Rubber Laboratory in its isolated location in the tropics several thousand miles from any other technical library.
It
