BS ISO 125:2020 pdf free.Natural rubber latex concentrate – Determination of alkalinity.
BS ISO 125 1 Scope This document specifies a method for the determination of the alkalinity of natural rubber latex concentrate. The method is not necessarily suitable for latices from natural sources other than Hevea brasiliensis or for synthetic rubber latices, compounded latex, vulcanized latex or artificial dispersions of rubber. NOTE A method for the determination of the alkalinity of polychloroprene latex is specified in ISO 13773. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 123, Rubber latex一Sampling ISO 976, Rubber and plastics一Polymer dispersions and rubber latices一Determination of pH.A test portion of latex concentrate is titrated with acid to pH 6 in the presence of a stabilizer to prevent coagulation, either electrometrically or with methyl red as a visual indicator. The alkalinity is calculated from the quantity of acid required.Use distilled water or water of equivalent purity, wherever water is specified, and reagents of recognized analytical quality.Carry out the determination in duplicate.Add, while stirring, 10 cm3 of stabilizer solution (5.1) to about 200 cm3 of water in a 400 cm3 beaker. Weighing to the nearest 10 mg, add between 5 g and 10 g of the latex concentrate by difference from a weighing bottle and stir until thoroughly mixed. Ensure that the latex is added so that none runs down the side of the beaker (which could result in loss of ammonia) or down the side of the weighing bottle. Titrate the resulting mixture either by the method described in 8.2 or by that described in 8.3. Insert the electrode of the pH-meter and, with continual stirring, add sulfuric acid or hydrochloric acid solution (5.2) from a burette, adding the acid drop by drop on approaching the end point of pH 6,0土0,05. BS ISO 125 pdf download.