1 Scope
This part of GB/T 4498 specifies two methods for the determination of ash from raw, compounded and vulcanized rubbers. This part is applicable to raw, compounded or vulcanized rubbers of categories M, N, O, R and U described in GB/T 5576, except that:
——Method A is not applicable to the determination of ash from compounded or vulcanized rubbers containing chlorine, bromine or iodine.
——Method B is applicable to compounded or vulcanized rubbers containing chlorine, bromine or iodine, but not applicable to uncompounded rubbers.
——Lithium and fluorine compounds may react with silica crucibles to form volatile compounds, resulting in low ash determination results. Platinum crucibles shall therefore be used for ashing fluorine-containing and lithium-polymerized rubbers.
This part does not cover the interpretation of the ash results as to the inorganic chemical content of compounded or vulcanized rubbers. This is the responsibility of the analyst, who shall be aware of the behavior of various rubber ingredients at high temperature.
These two methods may not give identical results, and it is necessary to state in the test report the method of ashing employed.
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 (including any amendments) applies.
GB/T 5576 Rubber and latices - Nomenclature (GB/T 5576-1997, idt ISO 1629: 1996)
GB/T 15340 Rubber, raw natural and raw synthetic - Sampling and further preparative procedures (GB/T 15340-2008, ISO 1795: 2000, IDT)
GB/T 24131 Rubber, raw - Determination of volatile matter content (GB/T 24131-2009, ISO 248: 2005, MOD)
3 Method summary
3.1 Method A
Put the weighed test portion in a crucible and heat it over a temperature-adjustable electric furnace (or Bunsen burner). After expulsion of the volatile decomposition products, transfer the crucible to a muffle furnace where it is heated until all the carbonaceous matters are burnt off and the mass is constant.
3.2 Method B
Put the weighed test portion in a crucible, heat it over a temperature-adjustable electric furnace (or Bunsen burner) in the presence of sulfuric acid, and then put it into a muffle furnace to burn until all the carbonaceous matters are burned off and the mass is constant.
Foreword i
1 Scope
2 Normative references
3 Method summary
4 Reagents
5 Apparatus
6 Sampling and preparation of test portion
7 Procedure
8 Result calculation
9 Tolerance
10 Test report
