Standards related to:

GB/T 40275-2021**GB/T 40275-2021: PDF in English (GBT 40275-2021) **

GB/T 40275-2021

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

ICS 59.080.01

CCS W 04

Textiles - Quantitative Analysis of Bicomponent Fiber -

Melting Microscopy Method

ISSUED ON: MAY 21, 2021

IMPLEMENTED ON: DECEMBER 1, 2021

Issued by: State Administration for Market Regulation;

Standardization Administration of the People’s Republic of

China.

Table of Contents

Foreword ... 3

1 Scope ... 4

2 Normative References ... 4

3 Terms and Definitions ... 4

4 Principle ... 4

5 Instruments, Equipment and Materials ... 5

6 Test Procedures ... 5

7 Calculation and Result Expression ... 7

8 Test Report ... 8

Appendix A (informative) Cross-sectional Morphology of Sheath-core Type,

Paralleling Type, Fibril Matrix Type and Split Type of Bicomponent Fibers ... 9

Appendix B (informative) Volume Density and Melting Point of Conventional

Components in Bicomponent Fiber ... 11

Appendix C (normative) Determination of Coefficient of Variation, Allowable

Error Rate and Number of Increased Test Fibers ... 12

Bibliography ... 15

Textiles - Quantitative Analysis of Bicomponent Fiber -

Melting Microscopy Method

1 Scope

This Standard describes the method of adopting the melting microscopy method for

the determination of the mass fraction of each component in the bicomponent fiber.

This Standard is applicable to bicomponent fiber identifiable by melting and textile

products with unchanged appearance.

NOTE: for samples that can be tested by both the chemical dissolution method and this

Method, the chemical dissolution method is preferred.

2 Normative References

The content of the following document constitutes indispensable clauses of this

document through the normative references in the text. In terms of references with a

specified date, only versions with a specified date are applicable to this document. In

terms of references without a specified date, the latest version (including all the

modifications) is applicable to this document.

FZ/T 01101-2008 Textile Test Method - Fiber Content - Quantitative Physical Analysis

3 Terms and Definitions

The following terms and definitions are applicable to this document.

3.1 Bicomponent Fiber

Bicomponent fiber refers to a fiber composed of two high polymers with different

chemical or physical structures.

NOTE: bicomponent fibers include four types of structures: sheath-core type, paralleling

type, fibril matrix type and split type, etc.

4 Principle

After using a microscope to observe and collect the cross-sectional images of the

bicomponent fiber. In accordance with the different characteristics of melting point,

morphology, polarity and solubility, determine the corresponding fiber component;

collect images at 12 different positions; ensure that the images are not repeatedly

collected on the fibers. Among the 12 collected images, there shall be at least 120

fibers with clear cross-sections.

If the bicomponent is relatively approximate in morphology and size, it may cause

relatively significant interference to the quantitative determination. Collect 1 clear

image, then, at the same position, take the polarized image to assist the quantitative

determination.

6.3 Qualitative Analysis of Fiber Components

6.3.1 At a rate of 3 °C/min ~ 4 °C/min, raise the temperature of the fiber specimen on

the heating table. When a certain component melts, immediately transfer it to the heat

preservation state; record the melting temperature.

6.3.2 Fine-tune the digital metallographic stereo-microscope (5.5); magnify by 500 ~

1,000 times to observe the melting process of the low-melting component in the fibers.

After most of the component is melted, collect the post-melting image; continue to raise

the temperature; determine and record the melting point of the other component.

Combine the melting image, or supplemented by the difference of the polarized image,

determine the morphology of the bicomponent fiber (see Appendix A) and the

distribution position of each component in the clear image.

6.3.3 In accordance with the melting point of each component, conduct the qualitative

analysis; determine the corresponding volume density (see Appendix B).

NOTE: if the determined melting points of the bicomponent are relatively close, then, refer

to FZ/T 01057, supplemented by other qualitative methods to conduct the

identification.

6.4 Quantitative Determination of Fiber Components

6.4.1 Determination of cross-sectional area ratio of bicomponent

6.4.1.1 Method A: determination by digital fiber analysis software

Respectively import the 60 clear fiber cross-sectional images collected in 6.2 into the

digital fiber analysis software matching the digital metallographic stereo-microscope

(5.5). In accordance with 7.2.1.2 in FZ/T 01101-2008, determine the number of pixels

corresponding to the cross-sectional area of the bicomponent in each fiber; calculate

the ratio of the two; the result shall retain two decimal places.

6.4.1.2 Method B: determination by micro-projector

Respectively import the 60 clear fiber cross-sectional images collected in 6.2 into the

micro-projector (5.6). In accordance with 7.2.1.1 in FZ/T 01101-2008, determine the

cross-sectional area of the bicomponent in each fiber; calculate the ratio of the cross-

Appendix C

(normative)

Determination of Coefficient of Variation, Allowable Error Rate and Number of

Increased Test Fibers

C.1 Calculation of Coefficient of Variation

The coefficient of variation shall be calculated in accordance with Formula (C.1) and

Formula (C.2). The calculation result shall retain two decimal places; the third decimal

place is rounded when it is non-zero.

Where,

S---the standard deviation of the mass fraction of a certain component in the fiber,

expressed in (%);

X1i---the mass fraction of a certain component of the ith fiber, expressed in (%);

X1---the average mass fraction of a certain component in the fiber, expressed in (%);

N---the total number of test fibers;

CV---the coefficient of variation of the mass fraction of a certain component in the fiber,

expressed in (%).

C.2 Calculation of Allowable Error Rate

A large number of n test values are in approximately normal distribution. Under the

confidence level of 95%, the true value will fall within the interval of the arithmetic mean

value X ± C of the test result of the specimen. This interval is known as the confidence

limit. The half-width value C and the allowable error rate of the confidence interval shall

be calculated in accordance with Formula (C.3) ~ Formula (C.5):

......

Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.