GB/T 2910.26-2017Textiles -- Qualitative chemical analysis -- Part 26: Mixtures of melamine and cotton or aramide fibers (method using hot formic acid) (English PDF)

Foreword

GB/T 2910 "Textiles - Quantitative chemical analysis" contains the following parts:

- Part 1: General principles of testing;

- Part 2: Ternary fiber mixture;

- Part 3: Mixtures of acetate and certain other fibers (method using acetone);

- Part 4: Mixtures of certain protein and certain other fibers (method using

hypochlorite);

- Part 5: Mixtures of viscose, cupro or modal and cotton fibers (method using sodium

zincate);

- Part 6: Mixtures of viscose or certain types of cupro or modal or lyocell and cotton

fibers (method using formic acid and zinc chloride);

- Part 7: Mixtures of polyamide and certain other fibers (method using formic acid);

- Part 8: Mixtures of acetate and triacetate fibers (method using acetone);

- Part 9: Mixtures of acetate and triacetate fibers (method using benzyl alcohol);

- Part 10: Mixtures of triacetate or polylactide and certain other fibers (method using

dichloromethane);

- Part 11: Mixtures of cellulose and polyester fibers (method using sulfuric acid);

- Part 12: Part 12: Mixtures of acrylic, certain modacrylics, certain chloro-fibers,

certain elastane fibers with certain other fibers (method using dimethylformamide);

- Part 13: Mixtures of certain chloro-fibers and certain other fibers(method using

carbon disulfide/acetone);

- Part 14: Mixtures of acetate and certain chloro-fibers (method using acetic acid);

- Part 15: Mixtures of jute and certain animal fibers (method by determining nitrogen

content);

- Part 16: Mixtures of polypropylene and certain other fibers (method using xylene);

- Part 17: Mixtures of chloro-fibers (homopolymers of vinyl chloride)and certain

other fibers(method using sulfuric acid);

- Part 18: Mixtures of silk and wool or hair (method using sulfuric acid);

Textiles - Quantitative chemical analysis - Part 26: Mixtures

of melamine and cotton or aramide fibers (method using hot

formic acid)

Caution - The substances or methods used in this section may be harmful to human

health and the environment if used improperly. This Part only involves technical

applicability-related content, at any stage the user is responsible for taking

appropriate health and safety and environmental measures.

1 Scope

This Part of GB/T 2910 specifies the method for determining the content of melamine

fiber in a bi-component mixture of melamine fiber and cotton or aramid, after removal

of non-fibrous matter, by the hot formic acid method.

This Part applies to the mixture of melamine fiber and cotton or aramid.

Note: Appendix A gives the qualitative identification method of melamine fiber. Appendix B

gives the quantitative chemical analysis method of the bi-component mixture of melamine fiber

and polyester fiber, polyamide fiber or spandex.

2 Normative references

The following documents are essential to the application of this document. For the dated

documents, only the versions with the dates indicated are applicable to this document;

for the undated documents, only the latest version (including all the amendments) is

applicable to this standard.

GB/T 2910.1 Textiles - Quantitative chemical analysis - Part 1: General principles

of testing (GB/T 2910.1-2009, ISO 1833-1:2006, IDT)

3 Terms and definitions

The following terms and definitions apply to this document.

3.1

Melamine fiber

Fibers formed from cross-linked macromolecules, which are composed of at least

85% (mass fraction) melamine derivatives.

4 Principles

Use 90% (mass fraction) hot formic acid solution, to dissolve and remove the melamine

fiber from the mixture of known dry mass. Collect the residue. Wash, dry and weigh it.

Use the corrected mass, to calculate its dry mass percentage of the mixture. The mass

percentage of melamine fiber is obtained from the difference.

5 Reagents

6 Instruments

7 Test steps

Follow the general procedures specified in GB/T 2910.1. Then follow the steps below.

8 Calculation and presentation of results

The calculation and presentation of the results shall be in accordance with the

provisions of GB/T 2910.1.

Cotton and aramid have a d-value of 1.02.

9 Precision

For homogeneously blended textile material mixtures, at the 95% confidence level, the

confidence limit for this method does not exceed +/-2.

Appendix B

(Informative)

Quantitative chemical analysis method of bi-component mixture of melamine

fiber and polyester fiber, polyamide fiber or spandex

B.1 Bi-component mixture of melamine fiber and polyester fiber (75% sulfuric

acid method)

B.1.1 Principle

Use 75% sulfuric acid solution, to dissolve and remove the melamine fiber from the

mixture of known dry mass. Collect the residue. Wash, dry and weigh it. Use the

corrected mass, to calculate the percentage of the dry mass of the mixture. The mass

percentage of melamine fiber is obtained from the difference.

B.1.2 Reagents

B.1.2.1 Use the reagents, which are specified in GB/T 2910.1 and B.1.2.2 and B.1.2.3

of this Part.

B.1.2.2 75% (mass fraction) sulfuric acid solution: Carefully add 700 mL of

concentrated sulfuric acid (density rho = 1.84 g/mL) to 350 mL of water. Cool the solution

to room temperature. Then add water to 1 L.

B.1.2.3 Diluted ammonia solution: Use water, to dilute 80 mL of ammonia water

(density rho = 0.880 g/mL at 20 °C) to 1 L.

B.1.3 Instruments

B.1.3.1 Use the instruments, which are specified in GB/T 2910.1 and B.1.3.2 and

B.1.3.3 of this Part.

B.1.3.2 Conical flask with a stopper, which has a capacity of not less than 200 mL.

B.1.3.3 Oscillating water bath, or other heating equipment, which can keep the

temperature at (90 +/- 2) °C.

B.1.4 Test procedure

Follow the general procedures, which are specified in GB/T 2910.1. Then follow the

steps below.

Put the prepared specimen into the conical flask (B.1.3.2). Add 100 mL of 75% sulfuric

acid solution (B.1.2.2) per gram of specimen. Cover the glass stopper. Shake the flask

to wet the specimen. Place it in a constant temperature water bath at (90 +/- 2) °C for 1

h. Shake it once every 10 min, to fully dissolve the melamine fiber. Cool the flask to

room temperature. Filter the residue into a glass sand core crucible. Drain the liquid by

vacuum suction. Add 50 mL of 75% sulfuric acid solution (B.1.2.2) into the crucible,

to clean the residue. Drain it under gravity, for at least 1 min, before use vacuum suction.

Continuously wash with water for several times. Use dilute ammonia solution (B.1.2.3),

to neutralize it twice. Then use cold water to wash it. Drain it under gravity and then by

suction for each wash. Finally, dry, cool, weigh the crucible and residue.

B.1.5 Calculation and presentation of results

The calculation and presentation of the results shall be in accordance with the

provisions of GB/T 2910.1. The d value of polyester fiber shall be 1.00.

B.2 Bi-component mixture of melamine fiber and polyamide fiber (formic acid

method)

The involved principles, reagents, instruments, test procedures, calculation and

presentation of results shall be performed, in accordance with GB/T 2910.7. The d value

of melamine fiber shall be 1.04.

B.3 Bi-component mixture of melamine fiber and spandex (dimethylformamide

method)

The involved principles, reagents, instruments, test procedures, calculation and

presentation of results shall be performed, in accordance with GB/T 2910.12. The d

value of melamine fiber shall be 1.05.

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