SN/T 5269-2019 in English

Technical Background of the Standard

This standard was issued by the General Administration of Customs in 2019. It establishes a standardized operating procedure for thermogravimetric analysis to meet the testing needs for the raw rubber content of chloroprene rubber composites. As the industry's first testing standard specifically for chloroprene rubber, it fills the technical gap in the testing of composite rubber polymer content.

Principle of the method

Key technical requirements

Instrument accuracy: The thermogravimetric balance must be accurate to 0.1mg, and the nitrogen purity requirement is >99.999%. Experimental data show that the repeatability limit of this method within the content range of 50.3%-90.2% is 0.7%-1.0%.

Pretreatment requirements: The amount of solvent extract must be determined according to ISO 1407 first. The filler content in a typical formula can reach up to 223 parts (when the rubber content is 30%).

Implementation recommendations

1. When establishing a laboratory-specific calibration curve, it is recommended to cover the rubber content range of 40%-100%
2. Calibration models should be established for samples of different vulcanization states
3. Regularly verify the instrument status with CR110/CR121 standard samples

Technology evolution analysis

Compared with the traditional solvent extraction method, the thermogravimetric analysis method shortens the detection time from 8 hours to within 1 hour and avoids the use of organic solvents. However, attention should be paid to the potential impact of the decomposition temperature of fillers such as carbon black (usually >600°C) on the test results.