Carbon fiber—Determination of density
1 Scope
This standard specifies three methods for the determination of the density of carbon fiber yarn:
——method A: liquid-displacement method;
——method B: sink/float method;
——method C: density-gradient column method.
Method C is the reference method.
This standard is applicable to continuous carbon fiber yarn and fixed length carbon fiber yarn.
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 documents (including any amendments) applies.
GB/T 2918 Plastics—Standard atmospheres for conditioning and testing (GB/T 2918-1998, ISO 291: 1997, IDT)
GB/T 15223 Plastics—Liquid resins—Determination of density by the pyknometer method (GB/T 15223-2008, ISO 1675: 1985, IDT)
GB/T 29761 Carbon fiber—Determination of size content (GB/T 29761-2013, ISO 10548: 2002, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
density
mass per unit volume of a substance at a specified temperature, in g/cm3 or kg/m3, with recommended temperature of 23°C
4 Specimen
The size shall be removed from the specimen unless otherwise agreed. Soxhlet extractor method, sulfuric acid and hydrogen peroxide mixed solution digestion method and high temperature decomposition method specified in GB/T 29761 can be used to remove the size. If the supplier and the purchaser agree, the specimen containing size can also be used for testing. The density of specimen containing size may be taken to be identical to that of size-free specimen when the size content is low.
5 Conditioning
Before testing, the specimens shall be conditioned under the temperature and humidity conditions specified in GB/T 2918, and tested under the same temperature and humidity conditions. The preferred conditions are the temperature of 23°C ± 2°C and the relative humidity of (50 ± 10)%.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Specimen
5 Conditioning
6 Test methods
7 Test report
Annex A (Normative) Preparation of the density-gradient column
Annex B (Informative) Precision
