GB/T 14344-2022Man-made fibre—Test method for tensile properties of filament yarns (English PDF)

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.

3.2 Stress

Stress refers to the resistance of fibers subject to an external force to deformation.

3.3 Strain

Strain refers to the deformation of fibers due to an external force.

3.4 Modulus

Modulus is a parameter used to characterize the deformation behaviors of fibers. On a stress - strain curve, modulus is the ratio of stress increment to strain increment.

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.

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.

5.1 Constant-rate Elongation Tensile Tester (CRE)

5.1.1 The instrument shall be equipped with the following devices.

5.1.2 The instrument shall comply with the following technical requirements.

5.1.3 The type recommendation of the clamp holder is as follows.

5.2 Other Test Tools and Materials

5.2.1 Skein length measuring instrument. used to prepare laboratory samples into test strands; the circumference of the yarn frame is (1.000 ± 0.002) m; it has a reciprocating wire guide device and a circle counting device.

5.2.2 Telescopic cylinder. used for the specimen preparation of unsupported packaged filaments; for twisted filaments, during humidity-conditioning or relaxation, it can prevent the loss of twist.

Guide Groove 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.

5.2.6 Nonionic surfactants.

6.1 Sampling

6.1.1 Laboratory sample drawing

Laboratory samples are drawn in the following modes.

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.

6.2 Humidity-conditioning and Pre-conditioning --- Applicable to Wet-state Test

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).

6.3.1.2 The pre-tension per unit linear density is recommended as follows.

6.4 Number of Tests

The number of tests is specified as follows in accordance with different situations.

7.1 Determination of Linear Density

In accordance with the stipulations of GB/T 14343, determine the average linear density of the same laboratory sample.

7.2 Specimen Loading

To manually or automatically load the specimen, the following rules need to be followed.

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.

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.

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.

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.

8.1 Breaking Elongation

8.1.1 During start-up with pre-tension, the breaking elongation is calculated in accordance with Formula (2).

8.1.2 During start-up with relaxation, the initial length is calculated in accordance with Formula (3).

8.2 Breaking strength

The breaking strength is calculated in accordance with Formula (4) or Formula (5).

8.3 Constant Force Elongation

The constant force elongation is calculated in accordance with Formula (6).

8.4 Modulus

The modulus is calculated in accordance with Formula (7) or Formula (8).

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).

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%.

8.10 Result Expression

The test results are expressed as the arithmetic mean of valid test values.