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GB/T 14338-2022 English PDF (GBT14338-2022)

GB/T 14338-2022 English PDF (GBT14338-2022)

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GB/T 14338-2022: Man-made fibre -- Test method for crimping performance of staple fibre
This document describes the test method for the crimping performance of man-made fiber -- staple fiber. This document is applicable to man-made fiber -- staple fiber.
GB/T 14338-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.060.20
CCS W 50
Replacing GB/T 14338-2008
Man-made Fiber - Test Method for Crimping Performance
of Staple Fiber
ISSUED ON: APRIL 15, 2022
IMPLEMENTED ON: NOVEMBER 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 5
4 Principle ... 5
5 Instruments and Tools ... 5
6 General Rules of Test ... 6
7 Test Procedures ... 8
8 Result Calculation ... 9
9 Test Report ... 10
Appendix A (informative) Calculation Method for Heavy Tension ... 11
Appendix B (normative) Calculation of Statistical Values and Increased Number of Test Fibers ... 12
Appendix C (normative) Crimp Counting Method ... 15
Man-made Fiber - Test Method for Crimping Performance
of Staple Fiber
1 Scope
This document describes the test method for the crimping performance of man-made fiber --- staple fiber.
This document is applicable to man-made fiber --- staple fiber.
2 Normative References
The contents of the following documents constitute 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. GB/T 4146 (all parts) Textiles - Man-made Fibers
GB/T 9994 Conventional Moisture Regains of Textile Materials
GB/T 14334 Sampling Method for Man-made Staple Fibers
3 Terms and Definitions
The terms and definitions defined in GB/T 4146 (all parts) are applicable to this document. 4 Principle
Under the specified tension, read the crimp peak and crimp valley of the fiber; under different tensions, within a certain stress time, determine the length variation of the fiber. Thus, the crimping performance data, such as: crimp number, crimp rate, crimp recovery rate and crimp elasticity of the fiber is obtained.
5 Instruments and Tools
5.1 Crimp elasticity tester, which needs to satisfy the following requirements: a) The force measurement error is less than or equal to 1%;
b) Length resolution: 0.01 mm;
c) Equipped with a device for precise calibration of the instrument.
5.2 Fleece board: form a contrasting color with the fiber.
5.3 Tweezers, etc.
6 General Rules of Test
6.1 Sampling
The rules of the sampling are as follows:
---For the laboratory samples of bulk items, take out as needed, and the minimum size shall not be less than 10 g;
---For the laboratory samples from batch samples, conduct the sampling in accordance with the stipulations of GB/T 14334.
Packages that are accidentally damp, damaged or opened during transportation shall not be taken as samples.
6.2 Pre-conditioning, Standard Atmosphere for Humidity-conditioning and Testing, and Humidity-conditioning Time
6.2.1 Pre-conditioning
When the sample complies with one of the following conditions, pre-conditioning is required: ---When the moisture regain of the specimen exceeds the conventional moisture regain; ---When the sample is in an atmosphere with a relative humidity higher than the upper limit of the relative humidity of the laboratory;
---When the temperature of the sample is 5 C lower than the laboratory temperature. Conditions for pre-conditioning: at a temperature not exceeding 50 C and a relative humidity of 10% ~ 25%, place for at least 30 min.
The conventional moisture regain shall comply with the stipulations of GB/T 9994. 6.2.2 Standard atmosphere for humidity-conditioning and testing
For the staple fiber with a conventional moisture regain less than 4.5%, the temperature is (20  2) C and the relative humidity is (65  5)%.
For the staple fiber with a conventional moisture regain greater than or equal to 4.5%, the Calculate in accordance with Formula (5):
Where,
Jdi---the crimp elasticity of a single fiber, expressed in (%);
L1i---the length of a single fiber when it is subject to heavy tension (7.4), expressed in (mm); L2i---after the load is removed, the length of a single fiber when it recovers for 2 min, then, is subject to light tension (7.5) again, expressed in (mm);
L0i---the length of a single fiber when it is subject to light tension (7.3), expressed in (mm). 8.5 Result Expression
All test results are expressed as the arithmetic mean of valid test values. 8.6 Calculation of Statistical Values
The calculation of statistical values, such as: arithmetic mean, standard deviation and coefficient of variation shall comply with Appendix B.
8.7 Data Rounding
All results are rounded to one decimal place.
9 Test Report
The test report shall include:
a) The Standard used (including year of issue);
b) The name and specifications of the sample;
c) The test method used and all test parameters;
d) The results of various performance tests of laboratory samples; if the standard deviation and coefficient of variation are calculated, then, they should be written into the report;
e) After negotiation, reminders for modification of test procedures and other parts inconsistent with this document;
f) Abnormal phenomena observed in the test;
g) Test personnel, test date.
Where,
CV---the coefficient of variation of n test results;
s---the standard deviation of n test results;
𝑥---the arithmetic mean of n tests.
B.2 Calculation of Increased Number of Test Fibers
B.2.1 Half-width value of confidence interval
The half-width value (c) of confidence interval of n test results is calculated in accordance with Formula (B.4):
Where,
c---the half-width value of confidence interval of n test results;
t---the value of t distribution (at the required 95% confidence level, it can be found through Table B.1);
s---the standard deviation of n test results;
n---the number of tests.
The half-width value (c) of confidence interval is usually expressed as a percentage of the arithmetic mean and calculated in accordane with Formula (B.5):
Where,
C---the half-width value of confidence interval expressed as a percentage of the arithmetic mean of n test results;
c---the half-width value of confidence interval of n test results;
𝑥---the arithmetic mean of n tests.
B.2.2 Re-determination of the number of test fibers
After testing n fibers, in accordance with Formula (B.5), calculate the half-width value (C) of confidence interval expressed as a percentage of the arithmetic mean of n test results. If it exceeds the specified allowable value, the number m of test fibers that shall be increased is
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