Coagulum

Latex continues to drip after the initial collection and coagulates naturally in the cup to form cup lump. Coagulum which forms as a film of latex on the tapped cut, called tree lace, or from latex that has dripped onto the ground, called earth scrap, is collected the next day along with the cup lump. Some smallholders may not collect the latex at all, but allow it to coagulate in the cup and collect it as cup lump. AH these methods produce mbber known as field coagulum. 

Eield latex and field coagulum are the source materials for all varieties and grades of dry natural mbber that include the conventional International grades as weH as the Technically Specified Rubbers (TSR). 

TSR 5. Within the Malaysian scheme SMR 5 is restricted to mbber derived from sheet material prepared by conventional processes, ie, ribbed smoked sheet (RSS), air-dried sheet (ADS), and unsmoked sheet (USS) and presented in small bale form. Other countries may source different raw materials, eg, Indonesia produces SIR 5 from thin latex coagulum (14). SMR 5 prepared by pressing dry-sheet material into standard bales must be identified by the type of sheet material, eg, SMR 5RSS, on the test certificate as well as on the wrapping. 

The quahty of the water used in emulsion polymerization has long been known to affect the manufacture of ESBR. Water hardness and other ionic content can direcdy affect the chemical and mechanical stabiUty of the polymer emulsion (latex). Poor latex stabiUty results in the formation of coagulum in the polymerization stage as well as other parts of the latex handling system. 

Blood Plasma and Serum. The terms plasma and semm are frequendy confused. Plasma refers to the Hquid that suspends the red cells within the body. Semm is that Hquid, removed from the body, from which the coagulum has been removed semm contains no coagulation factors and is severely depleted of platelets. 

Whey is the fluid obtained by separatiag the coagulum from cream and/or skim milk, and is a by-product of either caseia or cheese manufacture. The composition of whey is determined by the method of curd formation, curd handling practices, and methods of handling whey as it is separated from the curd. Dried acid whey contains ca 12.5 wt % proteia (total nitrogea x6.38), 11.0 wt % ash, and 59 wt % lactose, whereas sweet whey contains 13.5 wt % proteia, 1.2 wt % fat, 8.4 wt % ash and 74 wt % lactose. The composition varies with the type of acid used (7). 

Continuous polymerization in a staged series of reactors is a variation of this process (82). In one example, a mixture of chloroprene, 2,3-dichloro-l,3-butadiene, dodecyl mercaptan, and phenothiazine (15 ppm) is fed to the first of a cascade of 7 reactors together with a water solution containing disproportionated potassium abietate, potassium hydroxide, and formamidine sulfinic acid catalyst. Residence time in each reactor is 25 min at 45°C for a total conversion of 66%. Potassium ion is used in place of sodium to minimize coagulum formation. In other examples, it was judged best to feed catalyst to each reactor in the cascade (83). 

Comminuted and other new process rubbers. In these cases the coagulum is broken up and then dried. The rubber is then packed in flat bales similar in size to those used for the major synthetic rubbers (70-75 lb) unlike the heavier square bales used with smoked sheet and crepe rubbers. 

Too rapid initiation may lead to the agglomeration of the particles, which usually results in the formation of coagulum. 

If fresh blood is used in this preparation, it is convenient to remove much of the water in the following way. Seven liters of beef blood in a 12-I. round-bottomed flask is treated with 50 cc. of glacial acetic acid, and heated on a steam bath, with occasional stirring, until a thick, pasty coagulum results. About 41. of water is removed by distillation under reduced pressure, using a steam bath, and the residue is hydrolyzed as described above. 

With the use of exogenous pectinmethylesterase, the methanol content is lower because the demethylation of the pectin is not complete, part of the methylated pectin remaining in the coagulum and because the contact time between the PME and the pectin is shorter than in the past with the natural enzyme. 

C. Lopez. Influence de la nature de I interface matiere grasse/eau de laits reconstitues sur la cinetique de coagulation et les caracteristiques du coagulum. Stage de DEA et d ingenieur I.S.T.A.B., Universite de Bordeaux, 1997. 

In rubber latex, the process whereby the dispersed rubber globules separate out from the watery serum the globules clot together to form a jelly-like mass, the coagulum. In the preparation of natural rubber, coagulation of the latex is... 

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