ISO 248-2:2012 pdf download.Rubber, raw- – Determination of volatile-matter content-Part 2:Thermogravimetric methods using an automatic analyser with an infrared drying unit.
1.1 This part of ISO 248 specifies two thermogravimetric methods for the determination of moisture and other volatile-matter content in raw rubbers by using an automatic analyser with an infrared drying unit.
1.2 These methods are applicable to the determination of volatile-matter content in synthetic rubbers (SBR, NBR, BR, lR, CR, IIR, halogenated IIR and EPDM) listed in ISO 1629 and to various forms of raw rubber, such as bale, block, chip, pellet, crumb, powder and sheet. These methods might also be applicable to other raw rubbers, but in such cases it is necessary to prove that the change in mass is due solely to loss of original volatile matter and not to rubber degradation.
1.3 The methods are not applicable to raw rubbers which need homogenizing as specified in ISO 1795.
1.4 The hot-mill method and the oven method specified in ISO 248-1 and the methods specified in this part of ISO 248 might not give identical results. In cases of dispute, therefore, the oven method, procedure A, specified in ISO 248-1:2011 shall be 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.
2 Normative references
The following referenced documents are indispensable for the application 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 248-1:2011, Rubber, raw — Determination of volatile-matter content— Part 1: Hot-mill method and oven method
ISO 1629, Rubber and latices — Nomenclature
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
3 Principle
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.
4 Reagents
4.1 Sodium L-tartrate dihydrate, purity >= 99 %, for use as a standard reference material.
5 Apparatus
5.1 Automatic analyser
5.1.1 General
The automatic analyser shall consist of the following components:
a) an infrared drying unit or a far-infrared drying unit or a near-infrared drying unit;
b) a balance, capable of weighing to the nearest 1 mg;
c) a microprocessor, capable of controlling drying conditions such as the temperature and the drying end point, and of continuously calculating volatile-matter content as the mass lost during drying.
5.1.2 Performance requirements
The accuracy of the system shall be demonstrated by performing 10 successive determinations on the standard reference material sodium L-tartrate dihydrate. The mean of the 10 determinations shall be (15,66 ± 0,5) %. The relative standard deviation, obtained by the following equation, shall be less than 1,0 %.ISO 248-2 pdf download.