BS EN ISO 307 pdf free download

BS EN ISO 307-2019 pdf free download.Plastics – Polyamides – Determination of viscosity number.
4 Principle
The times of flow of a solvent and a solution of the polyamide at a concentration of 0,005 g/ml in the solvent are measured at 25 °C, the same viscometer being used for both measurements. The viscosity number is calculated from these measurements and from the known concentration of the solution.
5 Reagents and materials
5.1 Solvents and reagents
Only reagents of recognised analytical grade and only distilled water or water of equivalent purity shall be used.
WARNING — Some chemicals, for example
1,1,2,2-tetrachloroethane, are prohibited in some countries. The user shall check on the national regulations before applying the chemicals mentioned in this standard.
SAFETY STATEMENT Persons using this document should be familiar with laboratory practice. This document does not purport to address all of the safety concerns associated with its use. Some chemicals, for example
1,1,2,2-tetrachloroethane, are prohibited in some countries. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any regulatory requirements.
WARNING — Avoid contact with the skin and inhalation of any vapours of the solvents and cleaning liquids.
5.1.1 Sulfuric acid, 96,00 % ± 0,20 % (by mass) solution.
For the determination of the concentration of commercial sulfuric acid (95 % to 98 %) and adjustment to 96,00 %, see Annexes A and B.is referred to Annexes A and B.
5.1.2 Formic acid, 90,00 % ± 0,15 % (by mass) solution.
The solvent shall be stored in a brown glass bottle. Its concentration shall be checked at least every
2 weeks. It shall not contain more than 0,2 % acetic acid or methyl formate.
For the determination of the concentration of commercial formic acid (90 %) and adjustment to 90,00 % ± 0,15 %, see Annexes C is referred to Annexes A and DB.
5.1.3 m-Cresol, meeting the following specifications:
— appearance: clear and colourless;
— m-cresol content: 99 % (by mass) min.;
— o-cresol content: 0,3 % (by mass) max.;
— water content: 0,13 % (by mass) max.
m-Cresol of the required purity canmay be obtained by distillation of chemically pure m-cresol, preferably in vacuum.
To avoid oxidationIf distillation is used, nitrogen shall be used for pressure compensation to avoid oxidation. Its purity may be checked by gas chromatography. The solvent shall be stored in a brown glass bottle.
5.1.4 Phenol, 99 % (by mass) min.
5.1.5 1,1,2,2-tetrachloroethane, 99,5 % (by mass) min.
5.1.6 Phenol/1,1,2,2-tetrachloroethane.
Weigh out 6 parts by mass of phenol (5.1.4) and dissolve in 4 parts by mass of 1,1,2,2-tetrachloroethane (5.1.5). Work to an accuracy of 1 % or better in the weighings. Stir the mixture in its original container at 23 °C to prevent crystallization.
5.1.7 Orthophosphoric acid, 85 % (by mass), density 1,71 g/ml .
5.1.8 m-Cresol/phosphoric acid.
Transfer 50 ml of m-Cresol (5.1.3)cresol (5.1.3) into a weighing flask (6.4) and add with a glass pipette (6.5) 0,14 ml of orthophosphoric acid (5.1.7). Close the flask and stir with a magnetic stirrer for 30 min at 100 °C. Add the solution to approximately 800 ml of m-cresol in a volumetric flask while continuously stirring. Rinse the weighing flask several times with m-cresol and add this to the m- cresol solution. Remove the magnetic stirrer and dilute to the mark. Stir the solution for 30 min.
5.2 Cleaning liquids
5.2.1 Chromic acid solution, prepared by mixing equal volumes of sulfuric acid (96 %, ρ 0 = 1,84 g/ml, industrial quality) and a saturated solution of potassium dichromate (99,5 %, industrial quality). If required, the chromic acid solution may be replaced by other equally effective cleaning liquids.
5.2.2 Acetone (99,5 %, industrial quality), or any water-soluble low-boiling-point solvent
(industrial quality).
6 Apparatus
6.1 Vacuum drying cabinet, with pressure less than 100 kPa.
6.2 Balance, accurate to 0,1 mg.
6.3 Volumetric flask, of capacity 50 ml or 100 ml, complying with the requirements of ISO 1042, fitted with a ground-glass stopper.
6.4 Weighing flask, 100 ml, fitted with a ground-glass stopper.
6.5 Pipette, 0,2 ml, readable to 0,01 ml.BS EN ISO 307 pdf download.