SN/T 5271-2019Rubber and rubber products Fluorine rubber Thermogravimetric analysis for the determination of vulcanized and unvulcanized rubber (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed and managed by the General Administration of Customs of the People's Republic of China.

Drafting organization of this standard. Ningbo Customs of the People's Republic of China.

1 Scope

This standard specifies a method for the determination of total rubber hydrocarbon content in fluororubber using thermogravimetric analysis.

This standard applies to the determination of total rubber hydrocarbon content in fluororubber.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 6379.2 Measurement method and accuracy of results (accuracy and precision) GB/T 8170 Numerical rounding rules and the expression and determination of limit values ISO 1407 Determination of rubber solvent extractables

3 Method summary

A weighed sample is measured according to a preset temperature program. In a nitrogen atmosphere, the sample is first subjected to high temperature decomposition.

It is then oxidized in an oxygen atmosphere. The total rubber hydrocarbon content in fluorine rubber can be calculated by the mass change.

4 Reagents and materials

4.1 Nitrogen. purity >= 99.999%.

4.2 Oxygen. purity >= 99.999%.

5 Apparatus and equipment

5.1 Thermogravimetric analyzer. with platinum crucible, in which the balance is 0.001 mg.

5.2 Analytical balance. Sensitivity 0.1 mg.

6 Analysis steps

6.1 Turn on the thermogravimetric analyzer (5.1) and set the initial temperature of the heating furnace to 35 °C.

6.2 Cut the sample to approximately 1 mm × 1 mm.

6.3 Weigh a sample of 5 mg~8 mg, place it in a platinum crucible, and place it on the sample holder of the thermogravimetric analyzer (5.1), and read the quality of the sample.

Quantity (accurate to 0.001 mg).

Note. For some types of instruments, you can set the recorder to 100% after placing the sample. At this time, it is not necessary to pre-weigh accurately.

6.4 Close the heating furnace and purify the system with nitrogen gas (4.1) at a constant rate to ensure that the air in the furnace body is purged clean.

Note. The flow rate and purging time of nitrogen (4.1) are related to the model of the instrument, and can be set by referring to the instrument manual.

6.5 Under a nitrogen (4.1) atmosphere, raise the furnace temperature to 800 °C at a rate of 20 °C/min, and keep the temperature constant for 5 min.

6.6 Under nitrogen (4.1) atmosphere, reduce the furnace temperature from 800 °C to 400 °C; then switch the atmosphere from nitrogen (4.1) to oxygen (4.2), and keep constant temperature for 2 min.

Note. The flow rate of oxygen (4.2) should be consistent with the flow rate of nitrogen (4.2) in 6.4 to ensure that the total gas flow rate remains unchanged after the atmosphere is switched.

6.7 Under an oxygen (4.2) atmosphere, raise the furnace temperature to 800 °C at a rate of 20 °C/min, and keep the temperature constant for 10 min.

6.8 After the heating furnace has cooled to room temperature, open the furnace body, carefully take out the platinum crucible and clean it, and then end the test.

7 Analysis results

8 Precision

The precision data of this standard is determined by six laboratories conducting collaborative tests on samples with 3 levels of total rubber hydrocarbon content. Raw data press Perform statistics according to GB/T 6379.2 and calculate the repeatability limit and reproducibility limit. The precision is shown in Table 1.