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| GB/T 6509-2025 | English | 359 |
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Determination of caprolactam and oligomers content in polycaprolactam (PA6) chip and fibre
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GB/T 6509-2025
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| GB/T 6509-2005 | English | 209 |
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Testing method for determination of low molecular weight compounds content in chip and fibres of polycaproamide
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GB/T 6509-2005
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| GB/T 6509-1986 | English | 199 |
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Method for determination of low molecular weight compounds content in polyamide 6
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GB/T 6509-1986
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PDF similar to GB/T 6509-2025
Basic data | Standard ID | GB/T 6509-2025 (GB/T6509-2025) | | Description (Translated English) | Determination of caprolactam and oligomers content in polycaprolactam (PA6) chip and fibre | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | W50 | | Classification of International Standard | 59.060.20 | | Word Count Estimation | 18,158 | | Date of Issue | 2025-08-29 | | Date of Implementation | 2026-03-01 | | Older Standard (superseded by this standard) | GB/T 6509-2005 | | Issuing agency(ies) | State Administration for Market Regulation; Standardization Administration of China | GB/T 6509-2025: Determination of caprolactam and oligomers content in polycaprolactam (PA6) chip and fibre
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ICS 59.060.20
CCS W50
National Standards of the People's Republic of China
Replaces GB/T 6509-2005
Polycaprolactam (PA6) chips and fibers
Determination of caprolactam and oligomer content
Published on 2025-08-29
Implemented on 2026-03-01
State Administration for Market Regulation
The State Administration for Standardization issued a statement.
Foreword
This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1.Structure and Drafting Rules of Standardization Documents".
Drafting.
This document supersedes GB/T 6509-2005 "Determination of Low Molecular Weight Compounds in Polycaprolactam Chips and Fibers", and is consistent with...
Compared with GB/T 6509-2005, apart from structural adjustments and editorial changes, the main technical changes are as follows.
---The scope has been changed (see Chapter 1, Chapter 1 of the.2005 edition);
---Terminology and definitions have been changed (see Chapter 3, Chapter 3 of the.2005 edition);
---High performance liquid chromatography (HPLC) has been added (see Chapter 4);
---The test report has been amended (see Chapter 7, Chapter 6 of the.2005 edition).
Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.
This document was proposed and is under the jurisdiction of the National Technical Committee on Standardization of Chemical Fibers (SAC/TC586).
This document was drafted by. Zhejiang Sci-Tech University, Modern Textile Technology Innovation Center (Jianhu Laboratory), Haiyang Technology Co., Ltd., and Zhejiang University of Science and Technology.
Jiang Hengyi Petrochemical Research Institute Co., Ltd., Fujian Yongrong Jinjiang Co., Ltd., Changde Juhua Shun New Materials Co., Ltd., China Chemical Fiber
Industry Association, Shanghai Textile Science Research Institute Co., Ltd., Shanghai Textile Group Testing and Standards Co., Ltd., Xinxing Jihua Inspection and Testing (Beijing)
Beijing (Beijing) Co., Ltd., Jiangsu Hongsheng New Materials Co., Ltd., Zhejiang University, Shanghai Liangfeng New Materials Technology Co., Ltd., Jiaxing University, Shanghai
Jiangban Textile Technology Service Co., Ltd. of the Textile Science Research Institute, and Henan Shenmapuli Materials Co., Ltd.
The main drafters of this document are. Lü Wangyang, Chen Wenxing, Chen Haixiang, Chen Jianxin, Liang Xihui, Wang Xianjie, Yu Chenggang, Li Deli, and Li Hongjie.
Liang Na, Jing Penghui, Ding Wenxiang, Zhang Cailiang, Wang Yaomin, Yan Zhiyong, Tang Hao, Liu Quanshuai.
The release history of this document and the document it replaces is as follows.
---First published in 1986 as GB/T 6509-1986, and revised for the first time in.2005;
---This is the second revision.
Polycaprolactam (PA6) slices and fibers
Determination of caprolactam and oligomer content
Warning. This document should be used by personnel with practical experience in formal laboratory work. This document does not address all potential safety issues.
Users are responsible for taking appropriate safety and health measures and ensuring compliance with relevant national regulations.
1.Scope
This document describes a method for determining the caprolactam and oligomer content in polycaprolactam (PA6) chips and fibers.
Method A (High Performance Liquid Chromatography) in this document is applicable to polycaprolactam slices and polycaprolactam fibers (nylon 6), and other PA6.
The product should be followed according to the instructions; Method B (acid hydrolysis spectrophotometry) is applicable to polycaprolactam fibers (nylon 6); Method C (redox titration)
It is suitable for fiber-grade polycaprolactam slices, and also for the rapid determination of caprolactam and oligomers in polycaprolactam fibers within enterprises.
2 Normative references
The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.
For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.
This document.
GB/T 4146 (all parts) Textiles - Chemical Fibers
GB/T 6682 Specifications and test methods for water used in analytical laboratories
3.Terms and Definitions
The terms and definitions defined in GB/T 4146 (all parts) and the following terms and definitions apply to this document.
3.1
Polycaprolactam
PA6
Molecular formula. (C6H11NO)n, a polyamide formed by ring-opening polymerization of caprolactam.
Note. Its resin chips are scientifically known as polycaprolactam chips; if spun into fibers, they are polycaprolactam fibers, also known as nylon 6.
3.2
caprolactam
Monomers used for the polymerization of polycaprolactam (PA6).
Note. Residue found in polycaprolactam (PA6) chips or fibers.
3.3
oligomer
Oligomers with a degree of polymerization of less than 10 that exist in polycaprolactam (PA6) chips or fibers.
4.Method A – High Performance Liquid Chromatography
4.1 Principle
Polycaprolactam (PA6) slices or fiber samples were dissolved in hexafluoroisopropanol solvent, and then methanol was used as a precipitant to remove impurities from the sample solution.
Macromolecules are reprecipitated and separated in the sample solution using ultra-high performance liquid chromatography (UHPLC) or high performance liquid chromatography (HPLC).
Oligomers (see Appendix A) were qualitatively identified by retention time and UV spectroscopy, and quantitatively identified by external standard method.
4.2 Reagents or Materials
Unless otherwise specified, use only chromatographic grade reagents.
4.2.1 Water. GB/T 6682, Grade II.
4.2.2 Hexafluoroisopropanol. CAS No. 920-66-1, purity ≥99.5%.
4.2.3 Methanol. CAS No. 67-56-1.
4.2.4 Acetonitrile. CAS No. 75-05-8.
4.2.5 Caprolactam standard. CAS No. 105-60-2, purity ≥99.5%.
4.2.6 Caprolactam cyclic oligomer standard or reference standard. purity ≥95%. The preparation method for the caprolactam cyclic oligomer reference standard is attached.
Record B.
4.2.7 Sealing film.
4.3 Instruments and Equipment
4.3.1 Ultra-high performance liquid chromatograph or high performance liquid chromatograph. equipped with a diode array detector or ultraviolet detector.
4.3.2 Volumetric flasks. 25mL, 250mL.
4.3.3 Polytetrafluoroethylene needle filter. hydrophobic type, pore size ≤0.22μm.
4.3.4 Electronic balance. graduation value 0.1mg.
4.3.5 Constant temperature oscillating water bath. temperature control accuracy ±2℃.
4.4 Test Procedure
4.4.1 Chromatographic Reference Conditions
4.4.1.1 Reference conditions for ultra-high performance liquid chromatography
The reference chromatographic conditions for ultra-high performance liquid chromatography are as follows.
---Column. T3 column, 100mm × 2.1mm (inner diameter) × 1.7μm, or equivalent;
---Column temperature. 30℃;
---Flow rate. 0.3 mL/min;
---Detection wavelength..200nm;
---Injection volume. 2 μL;
---Mobile phase. Mobile phase A is water, and mobile phase B is acetonitrile (4.2.4);
---Eluting procedure. see Table 1.
Table 1.Elution Procedures for Ultra-High Performance Liquid Chromatography
time
min
Mobile phase A Mobile phase B
0 95% 5%
7.0 60% 40%
7.5 10% 90%
8.5 4% 96%
Table 1.Elution Procedures for Ultra-High Performance Liquid Chromatography (Continued)
time
min
Mobile phase A Mobile phase B
10.0 95% 5%
12.0 95% 5%
4.4.1.2 Reference conditions for high performance liquid chromatography
The reference chromatographic conditions for high performance liquid chromatography are as follows.
---Chromatographic column. C18 column, 250mm × 4.6mm (inner diameter) × 5μm or equivalent;
---Column temperature. 30℃;
---Flow rate. 1.0 mL/min;
---Detection wavelength..200nm;
---Injection volume. 20 μL;
---Mobile phase. Mobile phase A is water, and mobile phase B is acetonitrile (4.2.4);
---Eluting procedure. see Table 2.
Table 2 High Performance Liquid Chromatography Elution Procedures
time
min
Mobile phase A Mobile phase B
0 95% 5%
12.0 70% 30%
12.5 0% 100%
15.5 0% 100%
15.6 95% 5%
20.0 95% 5%
4.4.2 Plotting Standard Working Curves
Weigh caprolactam (C1) standard (4.2.5) and caprolactam cyclic oligomer (C2~C9) standard separately using an electronic balance (4.3.4).
Or, the reference standard (4.2.6) is placed in a 250 mL volumetric flask (4.3.2), with C1~C9 having masses of approximately 14 mg, 4 mg, 14 mg, 14 mg, and respectively.
14 mg, 14 mg, 14 mg, 8 mg, and 4 mg were dissolved in methanol (4.2.3) and diluted to volume to obtain a mixed standard stock solution. The concentration was determined by the actual weight.
The value was calculated. Then, the solution was serially diluted 2, 4, 8, 16, and 32 times to prepare a mixed standard working solution.
Store in the dark at 4℃~8℃.
The mixed standard working solution was determined using a chromatogram (4.3.1) under the chromatographic conditions described in 4.4.1.The concentrations of caprolactam and its cyclic oligomers (C1-C9) were determined.
Chromatograms and UV spectra are shown in Figures C.1 to C.3 of Appendix C. The peak areas of C1 to C9 are plotted on the ordinate, and the concentrations of the corresponding components of C1 to C9 are plotted on the ordinate.
Using the x-axis as the horizontal axis, plot the standard working curves for C1 to C9 respectively. The linear correlation coefficient should not be less than 0.999; otherwise, the standard working curves should be re-plotted.
Draw a curve.
4.4.3 Sample Preparation
Weigh 50 mg of the sample into a 25 mL volumetric flask (4.3.2) using an electronic balance (4.3.4), add 3 mL of hexafluoroisopropanol (4.2.2), and stopper the flask.
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GB/T 6509-2025: Determination of caprolactam and oligomers content in polycaprolactam (PA6) chip and fibre
Status: Valid
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