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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 6506-2001 Test method for crimp contraction properties of textured filament yarns.
The following main technical changes have been made with respect to GB/T 6506-2001:
——the application scope of the standard is extended (see Clause 1; Clause 1 of Edition 2001);
——for normative references, GB/T 6529 and GB/T 8170 are deleted, and GB/T 9994 is added (see Clause 2; Clause 2 of Edition 2001);
——the terms and definitions are deleted (see Clause 3; 3.1~3.6 of Edition 2001);
——the pre-tension accuracy requirements for twisted yarns taken by shaking are modified (see 5.1 and 8.3; 5.1 and 8.6 of Edition 2001);
——the temperature control accuracy requirements for oven temperature are modified (see 5.4 and 9.2; 5.4 and 9.2 of Edition 2001);
——the sampling method and sample requirements for laboratory samples of spare parts are added (see Clause 6; Clause 6 of Edition 2001);
——the standard atmosphere for conditioning and test is modified (see Clause 7; Clause 7 and 8.1 of Edition 2001);
——the set linear density of twisted yarn for specimens with linear density less than or equal to 400dtex is modified from the original Level I to Level II: where the linear density of the specimen is less than or equal to 200dtex, the set value is 2,500dtex; where the linear density of the specimen is greater than 200dtex and not greater than 400dtex, the set value is 5,000dtex (see 8.6; 8.7.1 of Edition 2001);
——the comparison table of linear density of specimens (≤200dtex) and number of twisted yarn loops for test (Table 1) is modified, and the comparison table of linear density of specimens (>200dtex, ≤400dtex) and number of twisted yarn loops for test (Table 2) is added (see Tables 1 and 2; 8.7.1 of Edition 2001);
——the crimp development time is modified (see 9.3; 9.3 of Edition 2001);
——the rounding-off digits of test result are modified (see Clause 10; 10.7 of Edition 2001).
This standard was proposed by China National Textile and Apparel Council.
This standard is under the jurisdiction of Shanghai Textile Industry Institute of Technical Supervision.
The previous editions of this standard are as follows:
——GB/T 6506-1986 and GB/T 6506-2001.
Synthetic fibre - Test method for crimp contraction properties of textured filament yarns
1 Scope
This standard specifies the test method for crimp contraction properties of textured filament yarns of synthetic fibre.
This standard is applicable to the textured filament yarns of synthetic fibre.
2 Normative references
The following referenced documents are indispensable for the application 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 - Chemical fibers
GB/T 6502 Sampling method of man-made filament yarns
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
For the purposes of this document, the terms and definitions given in GB/T 4146 (all parts) apply.
4 Principle
The length of twisted yarn with a certain total linear density will change after being curled and loaded according to the specified loading procedure. The crimp contraction property indexes such as crimp contraction CC, crimp modulus CM and crimp stability CS may be calculated using the length of twisted yarn measured according to the specified loading procedure.
5 Apparatus
5.1 Yarn length measuring machine
Yarn length measuring machine shall meet the following requirements:
——the circumference of the whole reel shall be (1,000±2)mm;
——a tension control system of (0.20±0.02)cN/dtex shall be provided during yarn swinging;
——the reel shall be equipped with a traversing gear to avoid overlapping of yarn loops.
5.2 Sample frame
The sample frame is used to hang the twisted yarn for test, it is generally of cylindrical or portal frame structure, with a row of hooks at the upper and lower ends respectively. The twisted yarn for test is hung between the upper and lower hooks; wherein, the upper hooks are fixed on the frame while the lower hooks are not fixed, which can not only increase and reduce the load, but also lift up and down along the guide wires on both sides without friction under the applied load, and can prevent the specimen from twisting (see Figure 1 for the structure). If necessary, the sample frame may be made into a frame which can be folded in half, and the twisted yarns for tests are not entangled with each other.
Figure 1 Schematic diagram for sample frame
5.3 Length measuring device
5.3.1 Visual inspection device
The device mainly consists of a measuring ruler with sufficient length (see Figure 2) and an accuracy of 1mm, with which the length of twisted yarn may be measured visually under different loads. The measuring ruler shall be perpendicular to the twisted yarn.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Sampling
7 Standard atmosphere for conditioning and test
8 Specimen preparation
9 Test procedures
10 Result calculation
11 Test report
Bibliography
