GB/T 9347-2025Determination of vinyl acetate content in vinyl chloride-vinyl acetate copolymers (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 supersedes GB/T 9347-1988 "Determination of Vinyl Acetate in Vinyl Chloride-Vinyl Acetate Copolymers" and is consistent with GB/T 9347- Compared to 1988, aside from structural adjustments and editorial changes, the main technical changes are as follows.

a) The principles have been changed (see 4.1, 5.1, Chapter 2 of the 1988 edition);

b) The reagents or materials have been changed (see 4.2, 5.2, Chapter 3 of the 1988 edition);

c) The instruments and equipment were modified (see 4.3, 5.3, Chapter 4 of the 1988 edition);

d) The experimental procedures were modified (see 4.4, 5.4, Chapters 5 and 7 of the 1988 edition);

e) The processing of experimental data was changed (see Chapter 6, 6.1 and 6.2 of the 1988 edition);

f) The permissible difference was changed (see Chapter 7, 6.3 of the 1988 edition);

g) The test report was amended (see Chapter 8, Chapter 8 of the 1988 edition).

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).

This document was drafted by: Jinxi Chemical Research Institute Co., Ltd., Tianjin Bohua Chemical Development Co., Ltd., and Hangzhou Keli Chemical Co., Ltd.

The company, Zhongyan Jilantai Chlor-Alkali Chemical Co., Ltd., Shandong Gaoxin Chemical Co., Ltd., and Shandong Xiang Sheng New Material Technology Co., Ltd.

The main drafters of this document are: Gao Xudong, Qi Yulin, Mi Guiting, Zhang Xinjiang, Pan Rui, Jin Shengbo, Guo Tao, Rong Xing, Li Yansong, and Shao Yueqing. Li Jinfeng.

This document was first published in 1988, and this is its first revision.

Introduction

GB/T 9347-1988, "Determination of vinyl acetate in vinyl chloride-vinyl acetate copolymers," is equivalent to ISO 1159 1978.

The principle of the method is as follows. the sample is dissolved in purified tetrahydrofuran, and the acetate is hydrolyzed with potassium hydroxide-ethanol solution; thymol blue is used as an indicator.

The excess potassium hydroxide was back-titrated with sulfuric acid; the hydrogen chloride released during hydrolysis was determined by argentometric titration. Because in parallel experiments, ethyl chloride...

The endpoint of the hydrolysis of vinyl acetate is extremely difficult to be consistent (it cannot be accurately controlled), so this method is difficult to achieve satisfactory accuracy and precision.

Furthermore, ISO 1159 1978 has been repealed. Therefore, it is necessary to revise GB/T 9347-1988.

GB/T 7139 "Determination of chlorine content in polyvinyl chloride homopolymers and copolymers" (the current valid version is GB/T 7139-2023) The principle is. burning the sample releases all the chlorine molecules from the sample, and then the chlorine content in the sample is measured. This method has been tested over a long period of time.

This revision of GB/T 9347-1988 is based on GB/T 7139-2023, which measures the chlorine content in the sample and then calculates the ethyl acetate content.

The content of olefins provides standard users with a more accurate detection method.

Vinyl acetate in vinyl chloride-vinyl acetate copolymer Determination methods Warning---Personnel using this document should have practical experience working in a formal laboratory. This document does not address all possible safety issues.

Users are responsible for taking appropriate safety and health measures and ensuring compliance with relevant national regulations.

1 Scope

This document describes a method for determining the vinyl acetate content in vinyl chloride-vinyl acetate copolymers.

This document applies to the determination of vinyl acetate content in vinyl chloride-vinyl acetate copolymers.

2 Normative references

GB/T 7139-2023

3 Terms and Definitions

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

4 Method A – Incendiary Bomb Method

5 Method B – Molotov cocktail method

6 Experimental Data Processing

The vinyl acetate content in the vinyl chloride-vinyl acetate copolymer is expressed as a mass fraction w, with the value expressed as a percentage (%), and is calculated according to formula (1). w=100- cM(V1-V2) 1000xm x 100 (1) In the formula.

c --- The concentration of the silver nitrate standard titration solution, in moles per liter (mol/L);

M --- Molar mass of vinyl chloride, in grams per mole (g/mol) (M=62.498);

V1 --- The volume of silver nitrate standard titration solution consumed in determining the sample, in milliliters (mL);

V2 --- The volume of silver nitrate standard titration solution consumed in the blank test, in milliliters (mL);

m --- the mass of the sample, in grams (g).

The calculation result should be rounded to one decimal place.

7 Allowable difference

The absolute value of the difference between two parallel determinations should not exceed 0.4% (Method A) or 0.8% (Method B). Take the results of the two parallel determinations...

The arithmetic mean is used to report the results.

8 Test Report

The test report should include.

a) Please indicate that this document is being cited;

b) Test subjects;

c) The test method used (method A or method B);

d) The mass fraction of vinyl acetate in the sample;

e) Observed anomalies;

f) Test date.