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GB/T 14344-2022 English PDF (GBT14344-2022)

GB/T 14344-2022 English PDF (GBT14344-2022)

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GB/T 14344-2022: Man-made fibre -- Test method for tensile properties of filament yarns

This document describes the test method for the tensile properties of man-made fiber -- filament yarns. This document is applicable to man-made fiber -- filament yarns, excluding spandex and carbon fiber.
GB/T 14344-2022
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 59.060.20
CCS W 50
Replacing GB/T 14344-2008
Man-made Fiber - Test Method for Tensile Properties of
Filament Yarns
ISSUED ON: APRIL 15, 2022
IMPLEMENTED ON: NOVEMBER 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Principle ... 8
5 Devices and Materials ... 8
6 General Rules of Test ... 10
7 Test Procedures ... 13
8 Result Calculation ... 15
9 Test Report ... 19
Appendix A (informative) Recommended Values of Twist Applied to Filament ... 20 Appendix B (normative) Quick Humidity-conditioning Method ... 21
Appendix C (informative) Calculation Method for Pre-tension ... 22
Appendix D (normative) Calculation Method for Increased Number of Tests ... 23 Appendix E (normative) Calculation of Statistical Values ... 25
Bibliography ... 27
Man-made Fiber - Test Method for Tensile Properties of
Filament Yarns
1 Scope
This document describes the test method for the tensile properties of man-made fiber --- filament yarns.
This document is applicable to man-made fiber --- filament yarns, excluding spandex and carbon 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 6502 Sampling Method of Man-made Filament Yarns
GB/T 6503 Man-made Fibers - Test Method of Moisture Regain
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods GB/T 9994 Conventional Moisture Regains of Textile Materials
GB/T 14343 Testing Method for Linear Density of Man-made Filament Yarns 3 Terms and Definitions
The terms and definitions defined in GB/T 4146 (all parts) , and the following terms and definitions are applicable to this document.
3.1 gauge length
Gauge length refers to the total fiber length measured when the clamping points of the first clamp holder and the second clamp holder are at the initial position.
[source: GB/T 4146.3-2011, 2.1.6, modified]
Example: the schematic diagram of the clamping point of a cable-pillar-type clamp holder is shown [source: GB/T 4146.3-2011, 2.5.28]
3.5 initial modulus
Initial modulus refers to the ratio of stress increment to strain increment of the initial straight line portion on a stress - strain curve of the fiber.
[source: GB/T 4146.3-2011, 2.5.29, modified]
3.6 work of rupture
Work of rupture refers to the work done by an external force when the fiber is stretched to rupture. That is, the energy absorbed in the process of the fiber being stressed, until it ruptures. 3.7 breaking roughness
Breaking roughness refers to the work done by an external force when a fiber of unit linear density and unit length is stretched to break.
4 Principle
Under the specified conditions, stretch the fiber to rupture on a constant-rate elongation tester, and obtain data of tensile properties, such as: breaking force, breaking elongation, constant force elongation, constant elongation force, initial modulus, work of rupture and breaking toughness of the specimens from the tensile curve or data acquisition system. 5 Devices and Materials
5.1 Constant-rate Elongation Tensile Tester (CRE)
5.1.1 The instrument shall be equipped with the following devices:
a) Manual or automatic specimen loading device;
b) Electronic force measuring device;
c) Automatic recorder capable of drawing tensile curves or data acquisition system; d) Clamp holder capable of holding fibers at a specified gauge length of at least 250 mm; e) Device for changing different stretching speeds.
5.1.2 The instrument shall comply with the following technical requirements: a) The maximum allowable difference between the actual force and the indicated force is less than 1% of the actual force;
5.2.3 Rotary creel: used for telescopic cylinders, so that the specimen is easy to unwind along the tangent line under low tension without changing the twist.
5.2.4 Water storage container: used to immerse the specimen in water.
5.2.5 Laboratory water: comply with Grade-3 water of GB/T 6682, at a temperature of (20 ??? 2) ???C.
5.2.6 Nonionic surfactants.
6 General Rules of Test
6.1 Sampling
6.1.1 Laboratory sample drawing
Laboratory samples are drawn in the following modes:
---For the laboratory samples of bulk items, take out as needed;
---For the laboratory samples from batch samples, conduct the sampling in accordance with the stipulations of GB/T 6502.
Packages that are accidentally damp, damaged or opened during transportation shall not be taken as samples.
6.1.2 Specimen preparation
6.1.2.1 From each package, remove at least 100 m of surface filament.
6.1.2.2 For unsupported packages, a skein length measuring instrument can be used to make strands with a length of at least 25 m; or on a telescopic cylinder, shake-take at least 25 m of filament.
6.1.2.3 For untwisted and non-network filaments, if it is impossible to prevent the specimen from slipping or the jaws from breaking, it can be twisted, so that the monofilaments in the multifilament can be subject to a certain tension, and the optimal test results can be obtained. The recommended values of twist applied to various filaments are shown in Appendix A. NOTE: proper twist increases the breaking force; excessively large / small twist reduces the breaking force. After twisting, the breaking elongation increases; the initial modulus decreases.
6.1.2.4 For specimens of the wet-state test, no humidity-conditioning is required. Add laboratory water at a temperature of (20 ??? 2) ???C to the water storage container and add a non-ionic surfactant with a maximum concentration of not more than 0.1% in the water. Take a section of specimen (more than 60 cm in length) and clamp both ends to prevent twist loss. Put it on the water surface of the water storage container; try to let the fiber freely sink and completely submerge in the water; soak it for 2 min. Throughout the operation, the loss of twist and unintentional stretching of the specimen shall be avoided.
It shall be noted that the process from taking the specimen out of the water to stretching to rupture shall not exceed 2 min.
The laboratory water in the water storage container shall be replaced at least once a week. 6.2 Humidity-conditioning and Pre-conditioning --- Applicable to Wet-state Test 6.2.1 Standard atmosphere for humidity-conditioning and testing
For filaments with a conventional moisture regain of less than 4.5%, the temperature is (20 ??? 2) ???C, and the relative humidity is (65 ??? 5)%.
For filaments with a conventional moisture regain of greater than or equal to 4.5%, the temperature is (20 ??? 2) ???C, and the relative humidity is (65 ??? 3)%.
The conventional moisture regain shall comply with the stipulations of GB/T 9994. 6.2.2 Humidity-conditioning time
6.2.2.1 Silk strands, telescopic cylinders and twisted specimens
When necessary, perform pre-conditioning. Under the condition that the temperature does not exceed 50 ???C and the relative humidity is 5% ~ 25%, place it for at least 30 min. The humidity-conditioning time shall comply with the stipulations of Table B.1 in Appendix B. 6.2.2.2 Packaged specimens
For filament packages with a conventional moisture regain of less than 4.5%, the humidity- conditioning time is at least 4 h.
For filament packages with a conventional moisture regain of greater than or equal to 4.5%, the humidity-conditioning time is at least 16 h.
Through negotiation between the demand-side and the supply-side, the quick humidity- conditioning method can be adopted in accordance with the stipulations of Appendix B. 6.3 Test Conditions
6.3.1 Pre-tension
6.3.1.1 The pre-tension of the specimen is calculated in accordance with Formula (1): Where,
F---the pre-tension, expressed in (cN);
P---the pre-tension per unit linear density, expressed in (cN/dtex);
T---the nominal linear density of the specimen, expressed in (dtex).
6.3.1.2 The pre-tension per unit linear density is recommended as follows: a) Drawn yarn, pre-oriented yarn, double shrinkage yarn, bulked filament, (0.05 ??? 0.005) cN/dtex;
b) Stretch textured yarn, aramid fiber, (0.20 ??? 0.02) cN/dtex;
c) Cellulose fiber, (0.05 ??? 0.005) cN/dtex in dry-state test; (0.025 ??? 0.0025) cN/dtex in wet-state test.
For filaments that are not suitable for the above-mentioned stipulations, it can be determined through negotiation between the demand-side and the supply-side, or the calculation method for the pre-tension can be determined through negotiation between the demand-side and the supply-side, see Appendix C.
6.3.2 Gauge length
When the average breaking elongation of the specimen is less than 50%, the gauge length is (500 ??? 1.0) mm;
When the average breaking elongation of the specimen is greater than or equal to 50%, the gauge length is (250 ??? 1.0) mm.
Through negotiation between the demand-side and the supply-side, other gauge lengths may also be adopted.
6.3.3 Stretching speed
In accordance with the stipulations of Table 1, select the displacement speed of the dynamic clamp holder. Through negotiation between the demand-side and the supply-side, other stretching speeds may also be adopted.
a) The strand specimen that has been subject to humidity-conditioning is cut into several specimens. Randomly take a specimen.
b) The telescopic cylinder that has been subject to humidity-conditioning is put into the rotary creel, and the filament is drawn out along the tangential direction. After fading and discarding the initial turns, take out a specimen. Pay attention to maintain the twist of the specimen constant.
c) For the twisted specimen that has been subject to humidity-conditioning, introduce one end into the jaws of the clamp holder and clamp it, pull the other end of the filament and maintain the twist of the specimen constant, then, introduce it into the jaws of another clamp holder.
d) For the package that has been subject to humidity-conditioning, after removing more than ten meters of the surface layer, put it on the creel of the tester, and put the filament end into the clamping device of the tester.
7.3 Start-up
7.3.1 Start-up with pre-tension
Introduce one end of the filament into the jaws of a clamp holder and clamp it; prevent twist changes or accidental stretching of the filament. Introduce the other end of the filament into the jaws of the other clamp holder, and apply the prescribed pre-tension to the end. Make sure that the filament is positioned in the center of the jaws of the clamp holder and clamp it. Turn on the tester and carry out the test. In addition, the initial length is equivalent to the gauge length.
7.3.2 Start-up with relaxation
Introduce one end of the filament into the jaws of a clamp holder and clamp it. Introduce the other end of the filament into the jaws of the other clamp holder and keep the specimen just in a relaxed state. Make sure that the filament is positioned in the center of the jaws of the clamp holder and clamp it.
Turn on the tester and carry out the test.
Test the displacement of the dynamic clamp holder from the initial position to a force equal to the standard pre-tension. At this moment, the initial length is not the gauge length. If the elongation is calculated in accordance with the stipulations of 8.1.2, this additional length does not affect the test results.
7.4 Determination of Tensile Properties
During the dry-state test, in accordance with the state of the specimen, choose an appropriate mode to load the specimen. During the wet-state test, adopt the manual mode to load the specimen.
In accordance with the test requirements, choose start-up with pre-tension or start-up with relaxation.
In accordance with the test conditions specified in 6.3, carry out the number of tests specified in 6.4.
Record the number of tests where jaw breakage (fiber breakage at or in the jaws) or slippage (fiber slipping in the clamp holder and leads to spurious growth) occurred. The number shall not exceed 10% of the total number of tests. Otherwise, check the clamp holder for abnormalities, and after adjustment or replacement, re-carry out the test. The results of jaw breakage or slippage shall not be counted, and additional specimens shall be supplemented for the test.
7.5 Data Collection
In accordance with the requirements, from the tensile curve or data acquisition system, determine the breaking force, breaking elongation, constant force elongation, constant elongation force, initial modulus, work of rupture and breaking toughness of each test. 8 Result Calculation
8.1 Breaking Elongation
8.1.1 During start-up with pre-tension, the breaking elongation is calculated in accordance with Formula (2):
Where,
???---the breaking elongation;
E---the elongation value of the laboratory sample stretched from the initial length to the break, expressed in (mm);
L0---the initial length, expressed in (mm).
8.1.2 During start-up with relaxation, the initial length is calculated in accordance with Formula (3):
Where,
Ls---the gauge length during start-up, expressed in (mm);
D---the displacement of the dynamic clamp holder from the initial position to a force equal to Where,
CM1---the modulus, expressed in (cN/dtex);
?????d---the increment of stress, expressed in (cN/dtex);
??????d---the increment of strain, dimensionless;
CM2---the modulus, expressed in (GPa);
??---the average density of the material of laboratory sample, expressed in (g/cm3); ???Fd---the increment of force, expressed in (cN);
??1---the average linear density measured from the same laboratory sample, expressed in (dtex); ???Ed---the increment of elongation, expressed in (mm);
L0---the initial length, expressed in (mm).
8.5 Initial Modulus
Near the original point of the tensile curve, take the point, where the change in force with the elongation is the maximum, and obtain the slope of the tangent line at this point. That is, the ratio of the difference in force to the difference in elongation at any two points on the tangent line. The initial modulus is calculated in accordance with Formula (9) or Formula (10): Where,
CMin-1---the initial modulus, expressed in (cN/dtex);
k---the slope of the tangent line at the point where the change in force with the elongation is the maximum, expressed in (cN/mm);
L0---the initial length, expressed in (mm);
??1---the average linear density measured from the same laboratory sample, expressed in (dtex); CMin-2---the initial modulus, expressed in (GPa);
??---the average density of the material of laboratory sample, expressed in (g/cm3). 8.6 Work of Rupture
The work of rupture is calculated in accordance with Formula (11):
Where,
????---the work of rupture, expressed in (J) or: (N ??? m);
F x+1---on the tensile curve, the force value of the (x+1)th data pair, expressed in (cN); F x---the force value of the xth data pair, expressed in (cN);
Ex+1---the elongation value of the (x+1)th data pair, expressed in (mm); E x---the elongation value of the xth data pair, expressed in (mm);
z---the total number of data pairs.
The work of rupture can also be expressed in (cN ??? mm), at this moment, only the values before 10?€?5 are reported.
8.7 Breaking Toughness
The breaking toughness is calculated in accordance with Formula (12):
Where,
EM---the breaking toughness, expressed in (J/g);
????---the work of rupture, expressed in (J) or: (N ??? m);
L0---the initial length, expressed in (mm);
??1---the average linear density measured from the same laboratory sample, expressed in (dtex). 8.8 Calculation of Statistical Values
Comply with the stipulations of Appendix E.
8.9 Data Rounding
For the breaking strength, initial modulus, work of rupture and breaking toughness, retain two decimal places.
For the breaking elongation, retain 0.1%; for the coefficient of variation, retain 0.01%. Appendix D
(normative)
Calculation Method for Increased Number of Tests
D.1 Overview
After the laboratory sample is subjected to N times of test, obtain the standard deviation (sb) between packages. If the half-width value (c) of the confidence interval exceeds the allowable value, then, it is necessary to increase the number of tests.
D.2 Half-width Value of Confidence Interval
The half-width value (c) of the confidence interval is calculated in accordance with Formula (D.1):
Where,
c---the half-width value of the confidence interval;
t---the value of t distribution (at the required 95% confidence level, it can be found through Table D.1);
sb---the standard deviation between packages;
N---the number of tests.
D.3 Re-determination of Number of Tests
The number of tests M that shall be increased for each package is calculated in accordance with Formula (D.2); the result is rounded up to an integer:
Where,
M---the number of tests that needs to be increased for each package, dimensionless; t---the value of t distribution (at the required 95% confidence level, it can be found through Table D.1);
N---the number of tests;

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