GB/T 46211-2025Plastics - Hardeners and accelerators for epoxide resins - Determination of free acid in acid anhydride (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document is modified to adopt ISO 7327:1994 "Determination of free acid in anhydrides of epoxy resin curing agents and accelerators".

This document has undergone the following structural adjustments compared to ISO 7327:1994.

---A chapter on "Terms and Definitions" has been added;

---Chapter 4 corresponds to Chapters 3 through 7 of ISO 7327:1994, with section 4.1 corresponding to Chapter 3 of ISO 7327:1994;

4.2 corresponds to Chapter 4 of ISO 7327:1994; 4.3 corresponds to Chapter 5 of ISO 7327:1994; 4.4 corresponds to ISO 7327.

Chapter 6 of ISO.1994; 4.5 corresponds to Chapter 7 of ISO 7327:1994;

---Chapter 5 has been added;

---Chapter 6 corresponds to Chapter 8 in ISO 7327:1994.

The technical differences between this document and ISO 7327:1994, and the reasons therefor, are as follows.

---The normative reference document GB/T 601 (see 5.2.3) has been added to adapt to my country's technical conditions;

---ISO 760 (see 4.2.1, 4.2.2) has been replaced with the normatively referenced GB/T 6283 to adapt to my country's technical conditions and add [further details needed].

Operability;

---The normative reference GB/T 6682 (see 4.2) has been added to adapt to my country's technical conditions;

---The normative reference GB/T 12808-2015 (see 4.3.5) has been added to adapt to my country's technical conditions;

---Added laboratory water quality requirements (see 4.2) to adapt to my country's technical conditions and increase operability;

---Added accuracy class requirements for single-mark pipettes (see 4.3.5) to adapt to my country's technical conditions and increase operability;

---When plotting the standard curve, the volume of the free acid standard solution was increased from 4 points to 10 points (see 4.4.2) to suit my country's...

Technical conditions;

---Polypotential titration (see Chapter 5) has been added to adapt to my country's technical conditions and better meet users' requirements for product quality control;

---Added requirements to the test report for indicating the calculation basis and test date for potentiometric titration [see Chapter 6 d) and f)], adding...

The document is easy to use and convenient to apply.

The following editorial changes have been made to this document.

---Added a warning;

---The test method in ISO 7327:1994 is listed as Method A. Spectrophotometry (see Chapter 4);

---Added a formula number for calculating the free acid content in acid anhydrides, denoted by w (see 4.5).

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed by the China Petroleum and Chemical Industry Federation.

This document is under the jurisdiction of the National Technical Committee on Plastics Standardization (SAC/TC15).

1 Scope

This document describes two methods for determining the free acid content in epoxy resin anhydride curing agents and accelerators. spectrophotometry and potentiometric titration.

method.

The spectrophotometric methods described in this document are applicable to most acid anhydrides, except for polyesters and oligomeric anhydrides (also known as "oligomeric anhydrides"). Potentiometric titration is suitable for...

Used for all acid anhydrides.

Note. Spectrophotometric tests on polyesters and oligomeric anhydrides show significant dispersion.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

GB/T 601 Preparation of Standard Titration Solutions for Chemical Reagents GB/T 6283 Determination of Moisture Content in Chemical Products - Karl Fischer Method (General Method) (GB/T 6283-2008) ISO 760:1978, NEQ GB/T 6682 Specifications and test methods for water used in analytical laboratories GB/T 12808-2015 Laboratory Glassware - Single-mark Pipettes

3 Terms and Definitions

This document does not contain any terms or definitions that need to be defined.

4 Method A. Spectrophotometry