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(Rubber and rubber products Fluorine rubber Thermogravimetric analysis for the determination of vulcanized and unvulcanized rubber)
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Basic data
| Standard ID | SN/T 5271-2019 (SN/T5271-2019) |
| Description (Translated English) | (Rubber and rubber products Fluorine rubber Thermogravimetric analysis for the determination of vulcanized and unvulcanized rubber) |
| Sector / Industry | Commodity Inspection Standard (Recommended) |
| Classification of Chinese Standard | G40 |
| Classification of International Standard | 83.140.01 |
| Word Count Estimation | 6,673 |
| Date of Issue | 2019 |
| Date of Implementation | 2020-07-01 |
| Issuing agency(ies) | General Administration of Customs |
SN/T 5271-2019: (Rubber and rubber products Fluorine rubber Thermogravimetric analysis for the determination of vulcanized and unvulcanized rubber)
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Rubber and rubber products-Fluorocarbon rubbers-Determination of
the composition of vulcanizates and uncured compounds by thermogravimetry
The People's Republic of China Entry-Exit Inspection and Quarantine Industry Standards
Issued by the General Administration of Customs of the People's Republic of China
2019-12-27 release
2020-07-01 Implementation
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.
The main drafters of this standard. Xu Shanhao, Yuan Lifeng, Zhang Ying, Lin Zhenxing, Wang Hao, Luo Chuan, Xi Zhongwei, Chen Tieshan.
Rubber and rubber products fluoroelastomer thermogravimetric analysis method
Determination of the composition of vulcanized and unvulcanized rubber
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 ℃.
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 ℃ at a rate of 20 ℃/min, and keep the temperature constant for 5 min.
6.6 Under nitrogen (4.1) atmosphere, reduce the furnace temperature from 800 ℃ to 400 ℃; 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 ℃ at a rate of 20 ℃/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
7.1 Record
Record the graphs of the two situations (see Figure 1) to perform the necessary calculations. These graphs are used to obtain the composition of various compounds.
content.
Note. The differential curve provided by the thermogravimetric analyzer varies from manufacturer to manufacturer. You can also use the mass loss percentage vs. temperature curve and
Differential graph of mass loss percentage versus temperature to obtain the content of various components.
Description.
Solid line-the graph of mass loss percentage and time;
Dotted line-differential graph of mass loss percentage versus time.
Figure 1 Schematic diagram of thermal weight loss
7.2 Total organic content
The first peak on the differential curve (point A) corresponds to the maximum pyrolysis rate in nitrogen (4.1), the mass loss of this part (w1)
It is the thermal decomposition of the sample before 800 ℃ under nitrogen (4.1) atmosphere, that is, the total organic content.
7.3 Carbon residue content
Fluorine rubber will not be completely pyrolyzed in nitrogen (4.1), leaving a small amount of carbonaceous residue. In order to burn off the carbonaceous residues, heat
The furnace is cooled to 400 ℃ and the atmosphere is switched from nitrogen (4.1) to oxygen (4.2), then the furnace is heated to 800 ℃ and maintained until the quality is reached
No more changes. The second peak (point B) on the differential curve corresponds to the combustion of carbonaceous residues in oxygen (4.2). The quality of this part
The quantity loss (w2) is the carbonaceous residue content.
7.4 Carbon black content
After all the carbonaceous residues are volatilized, the mass loss percentage when heated to 800 ℃ in oxygen (4.2) is the carbon black in the sample
content. The third peak on the differential curve (point C) corresponds to the combustion of carbon black in oxygen (4.2), the mass loss of this part (w3)
That is the content of carbon black.
7.5 Ash
When the temperature is maintained at 800 ℃ and the mass is no longer changed, the residual mass (w4) at this time is the ash content. Ash includes
Inorganic fillers and ash content of various inorganic and organic components that are pyrolyzed at lower temperatures.
7.6 Total rubber hydrocarbon content
Assuming that all non-rubber organic components can be extracted, the mass fraction of solvent extracts in rubber measured according to ISO 1407 is w5,
Then the total rubber hydrocarbon content is calculated according to formula (1).
7.7 Presentation of results
The final results of total organic content, carbon black content, ash content and total rubber hydrocarbon content are all reported in the form of mass percentage.
According to GB/T 8170, rounded to one decimal place.
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.
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