Test method of tensile properties for
high tenacity filament yarn
1 Scope
This standard specifies the test methods for breaking strength, elongation at break, initial modulus and tensile creep properties of high tenacity filament yarn.
This standard is applicable to ultra-high molecular weight polyethylene fiber, aromatic polyamide fiber (aramid fiber), carbon fiber and other high tenacity filament yarns (generally refer to filament yarns with breaking strength greater than 10 cN/dtex).
The test method for tensile creep properties in this standard is not applicable to the filament yarns whose elongation changes by more than 5% when a load of 1 cN/dtex is applied for 1 min.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions, of any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.
GB/T 3291.1 Textiles—Terms of textile material properties and test—Part 1: Fibre and yarn
GB/T 3291.3 Textiles—Terms of textile material properties and test—Part 3: General
GB/T 4146 Textile terms and terminology (parts of chemical fibers)
GB/T 6502 Sampling method for synthetic filament yarns
GB 6529 Textiles—Standard atmospheres for conditioning and testing
GB/T 8170 Rules for rounding off of numerical values
GB/T 14343 Testing method for linear density of synthetic filament yarns and textured yarns
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in GB/T 3291.1, GB/T 3291.3 and GB/T 4146 as well as the following apply.
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3.1
tensile creep
phenomenon of the materials, under the action of certain temperature and constant stress, suffering ever-increasing deformation with the time, used to characterize the dimensional stability of reinforced materials under constant load
4 Principle
Breaking strength and initial modulus: The specimen is stretched until it breaks, and the breaking force and elongation are obtained, and the breaking strength is calculated using the breaking force and linear density; the slope of the tangent line of the initial part near the straight line on the stress-strain (force-elongation) curve is obtained, and the initial modulus is calculated using the slope and linear density.
Tensile creep: Pre-tension is applied to the specimen to obtain the initial length, and then a certain load is applied for a certain time (or until the specimen length remains unchanged), and the specimen length is measured again to calculate the difference between the two lengths (i.e. creep elongation) and the percentage of the initial length, i.e. tensile creep elongation.
5 Test apparatus
5.1 Technical requirements of constant-rate-of-extension (CRE) testing machine:
——Error for measuring force, not greater than 1% of the full scale;
——Error for measuring elongation, not greater than 0.1 mm;
——Error of clamping distance, not greater than ±1 mm;
——The speed change of the lower clamp shall not exceed 5% of the specified speed, 1 s after the test starts;
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Test apparatus
6 Standard atmosphere for conditioning and testing
7 Sampling and specimen preparation
8 Determination of breaking force and elongation
9 Initial modulus
10 Determination of tensile creep properties
11 Test report
Annex A (Normative) Determination of linear density
