ISO 248-2:2019 pdf free
ISO 248-2:2019 pdf free.Rubber, raw – Determination of volatile-matter content
The hot-mill method and the oven method specified in ISO 248-1 and the methods specified in this document might not give identical results. In cases of dispute, therefore, the oven method, procedure A, specified in ISO 248- 1:2011, is the referee method.
NOTE These methods can be useful for routine determinations, e.g. quality control, when the measurement conditions for the automatic analyser are fixed for a particular raw rubber or grade of raw rubber.A test portion is continuously weighed to constant mass by a thermogravimetric method using an automatic analyser with infrared drying. The volatile-matter content is calculated as the mass lost during this procedure.
Take a laboratory sample in accordance with the method specified in ISO 1795, and then prepare a test portion of between 2 g and 15 g from the laboratory sample. The actual mass of the test portion depends on the type of analyser, the expected volatile-matter content, and the form of the sample.
For raw rubbers in bale form, the test portion shall be cut into small pieces of volume less than about 350 mm3 (in the ideal case of a cubic piece, the length of a side should be about 7 mm). This operation shall be carried out as quickly as possible so as not to lose volatile matter.
Either method A (which uses a pre- defined drying time) or method B (in which drying ends when the mass loss rate has decreased to a pre-defined level) can be chosen, provided the automatic analyser used offers the choice. The endpoint (the pre-defined drying time for method A or the pre-defined mass loss rate for method B) shall be determined for each of the two methods for each type or grade of rubber to be analysed. Examples of test conditions are given in Annex A.ISO 248-2 pdf free download.
