GB/T 14338-2022 Man-made fibre - Test method for crimping performance of staple fibre
1 Scope
This document describes the test method for crimping performance of man-made staple fibres.
This document is applicable to man-made staple fibres.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
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 fibres
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 4146 (all parts) apply.
4 Principle
Under the specified tension, the crimp peak and crimp valley of the fibre are read; under different tensions, the change of fibre length is determined within a certain stress time, so as to obtain the crimping performance data such as crimp frequency, crimp percentage, crimp recovery percentage and crimp elastic recovery percentage of the fibre.
5 Instruments and tools
5.1 Crimping elasticity instrument shall meet the following requirements:
a) the force value measurement error is less than or equal to 1%;
b) the length resolution is 0.01mm;
c) the means for accurately calibrating the instrument is provided.
5.2 Clearer plate: contrasting color with the fibre.
5.3 tweezers, etc.
6 General principles of test
6.1 Sampling
The sampling requirements are as follows:
——laboratory samples from bulk samples shall be taken as needed, and the minimum volume shall not be less than 10g;
——laboratory samples from lot samples shall be taken according to the requirements of GB/T 14334.
Samples shall not be taken from packages that are accidentally moistened or damaged during transport, or that have been opened.
6.2 Standard atmosphere for pre-conditioning, conditioning and test, as well as conditioning time
6.2.1 Pre-conditioning
Pre-conditioning is required when the sample meets one of the following conditions:
——the moisture regain of the sample exceeds the conventional moisture regain;
——the sample is in an atmosphere with relative humidity higher than the upper limit of laboratory relative humidity;
——the sample temperature is 5℃ below the laboratory temperature.
Conditions for pre-conditioning: place the sample for at least 30min at a temperature of not exceeding 50℃ and a relative humidity of 10%-25%.
See GB/T 9994 for the conventional moisture regain.
6.2.2 Standard atmosphere for conditioning and test
For staple fibres with a conventional moisture regain of less than 4.5%, the temperature is (20±2)℃ and the relative humidity is (65±5)%.
For staple fibres with a conventional moisture regain of greater than or equal to 4.5%, the temperature is (20±2)℃ and the relative humidity is (65±3)%.
6.2.3 Conditioning time
The conditioning time is selected according to Table 1. If the fibre has been pre-conditioned, the upper limit of the conditioning time may be taken, or the fibre may be weighed every other 30 minutes until the mass is constant.
Table 1 Conditioning time of various fibres
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Instruments and tools
6 General principles of test
7 Test steps
8 Calculation of results
9 Test report
Annex A (Informative) Method to calculate heavy tension
Annex B (Normative) Calculation of statistical values and increased number of test fibres
Annex C (Normative) Crimp counting method
