GB/T 43014-2023Polyimide short cut fibre (English PDF)

1 Scope

GB/T 43014-2023 specifies polyimide short cut fibre. Polyimide is the fibre used where nothing else survives: it holds its strength above 300 degrees, resists flame without a halogenated additive, and is chemically inert, which puts it into high temperature filter bags for cement and power plant flue gas, into protective clothing, and into friction and insulation materials. In short cut form it is a raw material for papers, felts and composites rather than a textile, so what a buyer needs specified is the linear density, the length distribution and the diameter. The standard sets the product identification, the technical requirements, the test methods, the inspection rules and the marking, packaging, transport and storage provisions, with normative annexes on converting between linear density and equivalent diameter and on the test method for diameter deviation. It took effect on 1 April 2024.

This document specifies the product identification, technical requirements, inspection rules, marking, packaging, transportation and storage of polyimide short cut fibre, and describes the test methods. This document applies to polyimide short cut fibres with a nominal linear density of

0.89 dtex ~

3.33 dtex, an equivalent diameter of 8.87 µm ~ 17.16 µm, and a cutting length less than 20 mm.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.

GB/T 4146 (all parts), Textiles - Man-made fibres

GB/T 6503, Man-made fibres - Test method of moisture regain

GB/T 14334-2006, Sampling method for man-made staple fibres

GB/T 14335, Testing method for linear density of man-made staple fibres

GB/T 14337, Man-made fibre - Test method for tensile properties of staple fibre

GB/T 14339-2008, Testing method for defect of man-made staple fibres

GB/T 37631, Man-made fiber - Test method for thermal decomposition temperature FZ/T 50016, Testing method for flame retardant property of viscose staple fibers - Oxygen index

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 4146 (all parts), as well as the following, apply.

3.1 temperature at 5% thermogravimetry weight loss Temperature at which the mass of the sample loses 5% when thermogravimetric analysis is performed under the same conditions under programmed temperature control and a certain atmosphere.

3.2 equivalent diameter Diameter of the circular cross-section fiber corresponding to the same linear density fiber.

3.3 overlength fibre Staple fiber whose length is greater than 130% of the nominal length and less than 2 times of the nominal length.

3.4 over short fibre Fiber whose fiber length is less than 70% of the nominal length.

4 Product identification

4.1 Product specifications The specifications of polyimide short cut fibres are expressed in terms of fiber linear density (equivalent diameter) and cutting length. Among them, the unit of linear density is decitex (dtex), the unit of equivalent diameter is micron (µm), and the unit of cutting length is millimeter (mm). The equivalent diameter corresponding to the linear density is calculated according to Appendix A. Example:

1.67 dtex (12.15 µm) × 6 mm.

4.2 Product identification Product identification shall include information such as product specifications, name or batch number.

5 Technical requirements

5.1 Product grading Products are divided into two grades: high-quality products and qualified products. Follow the provisions of GB/T 6503.

7 Inspection rules

7.1 Inspection classification Product inspection is divided into type inspection, ex-factory inspection and acceptance inspection. Type inspection shall be carried out when one of the following situations occurs:

a) during normal production, type inspection shall be carried out on a regular basis;

b) after formal production, if there are major changes in raw materials and processes that may affect the quality of the product;

c) when the factory inspection result is significantly different from the previous type inspection;

d) other times when type inspection is required.

Appendix C

(Normative) Test methods for length deviation, percentage of overlength staple fibres and percentage of over short fibres of polyimide short cut fibre C.1 Principle For polyimide short cut fibres with a nominal length of 4 mm and below, use a projector to enlarge the fiber length, and then use a steel ruler to measure the length of the sample on the projection screen to indirectly obtain the fiber length and count the number of fibers. Based on the nominal length, calculate the length deviation; based on the definitions of overlength staple fibre and over short fibre, calculate the percentage of overlength staple fibres and the percentage of over short fibres. For polyimide short cut fibres with a nominal length above 4 mm, use a vernier caliper to measure the fiber length directly. Based on the nominal length, calculate the length deviation of polyimide short cut fibre. C.2 Apparatus and reagents This test uses the following apparatus and reagents: -- Projector, magnification 20 times ~ 100 times; -- Steel ruler, minimum division value 1 mm; -- Vernier caliper, accuracy