ISO 2028 pdf download.Synthetic rubber latex — Preparation of dry polymer
1 Scope
This International Standard specifies four methods for the isolation of dry polymer from synthetic polymer latices con- taining anionic surfactants, for the purpose of subsequent testing. Tests that may be performed include the determi- nation of the Mooney viscosity, the bound-styrene or acrylonitrile content in the polymer chain or the mill shrinkage. Because of the wide variety of surfactants and stabilizers that are used in the manufacture of synthetic rubber latices, no one method is suitable for all latices. The methods given in this International Standard are suitable for a wide variety of latices, but their applicability should be confirmed for individual types. Latices containing non-ionic stabiliz- ers, in particular, may be resistant to coagulation. These methods are not necessarily suitable, without modification, for latices containing polymers having high tack. It should be noted that the dry polymer as isolated may contain residual organic acids or their aluminium salts which may affect the properties of the polymer. This should be taken into account when performing analytical tests.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publica- tions do not apply. However, parties to agreements based on this International Standard are encouraged to investi- gate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1 23:— 1 ) , Rubber latex — Sampling . ISO 1 24:1 997, Latex, rubber — Determination of total solids content .
3 Principle
The latex is coagulated in the presence of an antioxidant, using different procedures depending on the type of latex.
4 Reagents
During the preparation of the reagent solutions and the isolation of the polymer, use only distilled water or water of equivalent purity. 4.1 Coagulant A: An aqueous solution of a polyamine polyelectrolyte, prepared by dissolving of polyamine polyelectrolyte in of hot, water and then diluting the resultant solution to . NOTE 1 Suitable polyamine polyelectrolytes include “Prodefloc CRC 300C” (CAS No. 42751 -79-1 ) available from Industrie Chimiche Caffara SpA, Casella postale 327, 251 00 Brescia, Italy, and “EPI DNA” available from AcqueNYMCO SpA, 20032 Cormano MI, Via dei Giovi 6, Italy, Fax 66301 278. NOTE 2 Any residues of polyamine electrolyte left in the polymer following isolation are likely to interfere in the determination of bound acrylonitrile. 4.2 Coagulant B: A solution of aluminium sulfate in dilute sulfuric acid. Prepare dilute sulfuric acid by slowly and cautiously adding of concentrated sulfuric acid to of water and cooling. Separately, prepare a solution of aluminium sulfate by adding of aluminium sulfate solution to of water and straining through a piece of gauze. Add the diluted aluminium sulfate solution to the diluted sulfuric acid and adjust the volume to with water. 4.3 Antioxidant, for example trinonyl phenyl phosphite (TNPP). NOTE The antioxidant chosen should preferably be one known to be suitable for use with the polymer to be isolated. Prepare an aqueous emulsion of antioxidant containing of antioxidant in of emulsion. 4.4 Aluminium sulfate solution, prepared by dissolving of aluminium sulfate in water and diluting the resultant solution to . 4.5 Ethanol, minimum purity 99%.
5 Apparatus
Standard laboratory equipment plus the following: 5.1 Stainless-steel beaker, capacity. 5.2 Graduated cylinders, , and capacity. 5.3 Electric stirrer, with two propeller-type blades of approximately diameter, mounted apart at right angles to the shaft. 5.4 Magnetic stirrer. 5.5 Suitable device for injecting steam, fed from a low-pressure source. NOTE Steam is the most efficient method of heating liquids rapidly. 5.6 Gauze filter, e.g. cheese cloth. 5.7 Drying pan: An aluminium or enamel-lined pan with a suitable surface area (approximately ) on which to spread out the crumb for drying. It is desirable that the pan should be relatively light in weight. 5.8 Ventilated oven, capable of being maintained at . 5.9 Balance, capable of being read to .