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.
