Analysis Of Differences In Fiber Content Testing Standards Between China And The United States

fibre

The differences in the content test methods are compared and analyzed, providing relevant information for domestic production and trading enterprises, so that they can correctly analyze and label the product fiber content according to the export areas of the products, so as to meet the market requirements.

1 Characteristics of fiber content testing standards in the United States

American textile dyer and chemist Association (AATCC) in textile testing

The AATCC test standard has two methods for testing fiber content, AATCC20 standard is qualitative analysis of fiber, and AATCC20A standard is fiber quantitative analysis.

Qualitative analysis of fiber includes longitudinal observation and pverse section microscope observation, combustion method, density method, dissolution method, dry twist method, stick color method, melting point method and infrared spectrum method.

AATCC20A is quantitative analysis of fiber, including microscopic analysis, chemical dissolution and resolution.

2 differences between China's standards and US standards

The testing of fiber content of textile products in China is based on FZ/T 01057 - 2007 "textile fiber identification experiment method" and GB/T 2910 "textile quantitative chemical analysis".

In addition, there are other industry associations and related institutions, such as FZ/T 01095 - 2002, "experimental methods of fiber content of textile Spandex Products", GB/T 16988 - 1997 "determination of the content of mixtures of special animal fibers and sheep wool", FZ/T 30003 - 2009 "quantitative analysis of ramie cotton blended products" and FZ/T 01026 - 2009 "quantitative chemical analysis four component fiber mixture".

2.1 qualitative analysis of fibers

The most widely used method for fiber identification in all testing institutions should be microscopic observation and dissolution. For special fibers, combustion and infrared spectroscopy will be used. Other methods will be used less in the actual detection process due to accuracy and operability.

This paper briefly introduces the process and differences of several qualitative analysis methods.

2.1.1 microscopic observation

Microscopic observation relies on biological microscope as a tool to directly observe the longitudinal and pverse cross sections of the fibers through technical personnel, so as to preliminarily determine the type of fiber.

An experienced technician can judge the natural fibers such as cotton, linen, silk and wool by microscope, and some chemical fibers such as viscose and spandex.

AATCC 20 "qualitative analysis of fibers" and FZ/T 01057 - 2007 "textile fiber identification test methods", in addition to the description of the longitudinal and pverse appearance of each type of fiber, also provides a large number of fiber pictures, giving a more intuitive cognition.

2.1.2 dissolution method

China's industry standard FZ/T 1057.4 - 2007, "textile fiber identification test method of dissolution method" is required to use ambient temperature (20 C ~30 C) to oscillate 5min, or boil 3min to observe the dissolution of samples.

The dissolution test in AATCC20 provided 3 dissolution times for different fiber dissolution, namely 5min, 10min and 20min respectively.

The dissolution temperature is 50 degrees, 90 degrees and boiling at 20 degrees Celsius.

For example, the two methyl Methamide method is used to dissolve the confirmation test, and it is required to treat the dissolution phenomenon for 10 minutes at 90 degrees.

Due to the different dissolution conditions, the dissolution of some special fibers will be different. The inspectors should observe carefully and pay attention to differentiation.

2.1.3 dry twist method

In the AATCC20, the dry twisting method is used to preliminarily judge the hemp fibers.

Take parallel fiber bundles, immerse them in water, hold one end, make the other end of the free end facing the observer, heat the hot air on the electric stove. In the drying process, flax and ramie fibers rotate clockwise, and hemp and jute fibers rotate counterclockwise.

2.2 quantitative analysis of fibers

GB/T2910 - 2009 is equivalent to the latest version of ISO1833, except for some methods, which is much different from the American standard system.

The American AATCC20A standard includes moisture content, non fiber material removal, fiber content resolution, fiber content chemical analysis and fiber content microscopic analysis.

According to the different methods, the quantitative analysis of fiber in China has special standards.

In the analysis of domestic fiber content, we should pay special attention to the choice of methods. GB/T2910 is a quantitative chemical analysis of fiber (the manual resolution method is provided in Appendix). GB/T16988 is a microscope analysis method for animal fibers and so on.

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Quantitative chemical analysis of 2.2.1 fibers

AATCC20A provides 8 chemical analysis methods: 100% acetone method, 20% hydrochloric acid method, 59.5% sulfuric acid method, 70% sulfuric acid method, basic sodium hypochlorite method, 90% formic acid method, two methyl formamide and dimethyl acetamide method.

GB/T2910 provides 23 chemical analysis methods, covering all the testing methods of AATCC20A.

The differences between the two methods are analyzed from the aspects of sample preparation, reagent selection, testing process and data processing.

1) sample preparation (see Table 1)

Table 1 Comparison of sample preparation methods

Although the sampling weight is different, according to practical experience, the two standard sampling requirements can meet the representativeness and accuracy of the test.

In the sample weighing procedure, AATCC explicitly requested that the sample be dried to constant weight, and there is a definite requirement for constant weight.

GB/T2910 can also achieve the actual constant weight requirement with enough drying time, but AATCC20A is more operable.

2) reagent selection

In the same fiber content analysis process, AATCC is different from Chinese standard in the dissolution process (see Table 2).

Table 2 Comparison of dissolving agents for some methods

3) test procedure

The two standard test procedures are different. The most representative one is the chemical analysis of viscose fiber and cotton (see Table 3).

Table 3 Comparison of chemical analysis procedures for viscose and cotton blended products

Since viscose and cotton belong to cellulose fibers, two chemicals will damage cotton fibers when chemical dissolves. Any small differences in temperature, time and oscillation will affect the final result.

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4) data processing

Results when calculating, AATCC20A only introduced loss compensation coefficient for viscose fiber blended with cotton, and all other chemical analysis methods did not use any correction or compensation coefficient.

In GB/T 2910, the mass loss correction coefficient is provided for each type of test. The result is that the test data are calculated with the corresponding correction coefficient, which ensures the accuracy of the test results.

China's standards clearly stipulate that the percentage of fiber weight should be calculated according to the public regain.

Although there is no clear requirement in the US standard, the report issued by the testing organization is calculated according to the regrescent rate.

Due to the difference of the regain rate in the standard system of two countries, it may lead to the difference of results, so the correct regain value must be chosen when calculating.

Comparison of two typical fiber regain rates is shown in Table 4.

Table 4 Comparison of moisture regain of wool and regenerated cellulose fibers

Quantitative analysis by 2.2.2 microscope

The difference of microscope analysis is mainly shown in the result calculation, for example, the density of wool cashmere in AATCC20A is 1.31, but the density of wool in China is 1.31, and the density of cashmere is 1.30.

In the calculation formula, GB/T16988 calculates the area by combining the standard variance of the diameter, while AATCC20A only expresses the area by calculating the diameter.

2.3 content analysis of multi components

The content of GB/T2910.2 in China is analyzed by multi component content. 4 kinds of dissolution schemes are introduced in detail and combined with the mass loss correction coefficient.

In AATCC 20A, there is no such detailed calculation and analysis. In the process of multi component analysis, we should carefully choose the dissolution reagent and the dissolution sequence according to the work experience, so as to ensure that the selected reagent does not cause damage to the residual fibers, resulting in the reduction of data accuracy.

3 conclusion

To sum up, there are many differences between China and the United States in the method of fiber composition analysis. The testing institutions choose the testing methods according to the export locations of the products, and carry out tests.

Enterprises should pay attention to the difference between the test data and the national standard data when the products are exported to the United States.

The testing institutions should be proficient in the relevant test standards, and carry out strict analysis according to different methods when making component analysis, so as to ensure that the enterprises provide accurate experimental data.