BS ISO 1409:2020 pdf download – Plastics/rubber — Polymer dispersions and rubber latices (natural and synthetic) — Determination of surface tension

BS ISO 1409:2020 pdf download – Plastics/rubber — Polymer dispersions and rubber latices (natural and synthetic) — Determination of surface tension 8 Procedure 8.1 Method A 8.1.1 Preparation of apparatus Clean the dish or vessel (6.3) carefully, since any contamination may lead to variable results. Clean the ring of the tensiometer (6.1) by washing in water (5.1) and then heating in the oxidizing section of a Bunsen or ethanol flame (6.5). Take extreme care to avoid touching or distorting the tensiometer ring when handling it. Ensure that the ring remains parallel to the surface of the liquid during the determination. Failure to observe these precautions will lead to inaccurate results. 8.1.2 Calibration Carefully calibrate the tensiometer scale against a standard mass or a reference liquid such as distilled water (5.1) or toluene (5.2) in accordance with the manufacturer’s instructions, so that the scale reads in mN/m. Calibration is generally carried out against a standard mass. It should be noted that the calculation of the results (see Clause 9) requires different correction factors depending on the method of calibration. 8.1.3 Preparation of the test sample 8.1.3.1 If the total solids content of the test sample of latex or polymer dispersion is not known, determine it in accordance with ISO 124. If the mass fraction of total solids is greater than 40 %, dilute the test sample to a mass fraction of total solids of 40 % ± 1 % with water (5.1). If it is suspected that the viscosity of the diluted test sample is still greater than 200 mPa·s, determine it by the appropriate method given in ISO 1652, ISO 2555 or ISO 3219. If necessary, dilute the test sample further until the viscosity is less than 200 mPa·s, noting the final total solids content. NOTE Dilution to a mass fraction of 40 % has a negligible effect on the surface tension of polymer dispersions and rubber latices. In some cases, the surface tension at a higher total solids content can be required, in which case this can be measured by the method as specified with little loss of accuracy, provided that the viscosity is less than 200 mPa⋅s. If the density of the diluted test sample of latex or polymer dispersion is not known, determine it in accordance with ISO 705. 8.1.3.2 Using the thermostatic bath (6.4), adjust the temperature of the diluted test sample to 23 °C ±...