BS ISO 248-1:2021 pdf download.Rubber, raw — Determination of volatile-matter content.
4 Principle
4.1 Hot-mill method A test portion is sheeted out on a heated mill until all volatile matter is driven off. The loss in mass during milling is calculated and expressed as volatile-matter content.
4.2 Oven method A test portion is dried in an oven to constant mass. The loss in mass is calculated and expressed as the volatile-matter content.
5 Hot-mill method
5.1 General
5.1.1 Two procedures are specified, as follows. — Hot-mill method, procedure A: a test sample is homogenized using a laboratory mill, and a test portion from the homogenized test sample is dried to constant mass using a hot mill. — Hot-mill method, procedure B: a test portion is dried to constant mass using a hot mill. NOTE Procedure B is a simplified method which does not include a homogenization process.
5.1.2 When the sample is flaky or becomes sticky on the hot mill, making weighing difficult or impossible, the oven method shall be used.
5.1.3 The number of test portions shall be agreed between the interested parties.
5.2 Apparatus
5.2.1 Mixing mill, complying with the requirements of ISO 2393.
5.2.2 Balance, capable of weighing to the nearest 0,1 g.
5.3 Procedure
5.3.1 Hot-mill method, procedure A
5.3.1.1 Take a test sample of about 250 g from the laboratory sample in accordance with ISO 1795 and homogenize it in accordance with Annex B. Weigh to the nearest 0,1 g before and after homogenization (masses m 1 and m 2 , respectively). Cut the test portions needed for chemical and physical tests from the homogenized test sample, if necessary.
5.3.1.2 Adjust the clearance of the mill rolls to 0,25 mm ± 0,05 mm, using lead strips as specified in ISO 2393. Maintain the surface temperature of the rolls at 105 °C ± 5 °C.
5.3.1.3 Pass a weighed test portion (mass m 3 ), preferably of 100 g or more, taken from the homogenized test sample repeatedly through the mill for 4 min. Do not allow the test portion to band and take care to prevent any loss of material. Weigh the test portion to the nearest 0,1 g. Pass the test portion through the mill for an additional 2 min and reweigh. If the masses at the end of the 4 min and 6 min periods differ by less than 0,1 g, calculate the volatile-matter content. If not, continue passing the test portion through the mill for 2 min periods until the mass does not decrease by more than 0,1 g between successive weighings (final mass m 4 ). Before each weighing, allow the test portion to cool to room temperature in a desiccator.BS ISO 248-1 pdf download.