GB/T 42923-2023Glass-fibre-reinforced plastic products - Determination of fibre length (English PDF)

Foreword

This document was issued on 6 August 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 March 2024.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 42923-2023 covers the measurement of fibre length in glass-fibre-reinforced plastic products, and applies to discontinuous glass-fibre-reinforced thermoplastic moulding compounds. Its shape is that of a compact test method: a test principle, the test equipment, the test procedures, and the test report, with terms taken from ISO 472. Almost all of the document's substance is in the procedure clause, which is by far the longest. Specimen preparation starts from calcined ash — the polymer is burned away and the fibre recovered from what is left — and the amount of ash taken is set so that each image displayed on the screen contains roughly one hundred fibres, a working density thin enough for individual fibres to be told apart and measured on the image. That starting point is the reason the method exists: the length it reports is the length of the fibre as it survives in the finished product, after the compounding and moulding the fibre has been through, rather than the length of the fibre as it was supplied. Compounders, moulders and the engineers specifying reinforced thermoplastic parts use it, along with the laboratories checking incoming compound and outgoing mouldings on both sides of a supply contract.

This document describes the method for determining fiber length in glass-fiber-reinforced

plastic products.

This document is applicable to discontinuous glass-fiber-reinforced thermoplastic molding

compounds and molded parts. Before molding, the fiber length is less than or equal to 7.5 mm;

after molding, the fiber length is less than 1 mm.

NOTE: fiber-reinforced polymer matrix composites of other lengths may take this as a reference.

2 Normative References

The contents of the following documents constitute indispensable clauses of this document

through the normative references in the text. In terms of references with a specified date, only

versions with a specified date are applicable to this document. In terms of references without a

specified date, the latest version (including all the modifications) is applicable to this document.

ISO 472 Plastics - Vocabulary

NOTE: GB/T 2035-2008 Terms and Definitions for Plastics (ISO 472:1999, IDT)

ISO 1172 Textile-glass-reinforced Plastics - Prepregs, Molding Compounds and Laminates -

Determination of the Textile-glass and Mineral-filler Content - Calcination Methods

NOTE: GB/T 2577-2005 Test Method for Resin Content of Glass Fiber Reinforced Plastics (ISO

1172:1996, MOD)

3 Terms and Definitions

The terms and definitions defined in ISO 472 are applicable to this document.

Addresses of the terminology database maintained by ISO and IEC for standardization are as

follows:

---ISO online browsing platform: http://www.iso.org/obp;

---IEC electronic open platform: http://www.electropedia.org/.