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GB/T 35804-2018: Rubber, vulcanized or thermoplastic -- Resistance to ozone cracking -- Test methods for determining the ozone concentration in laboratory test chambers
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Rubber, vulcanized or thermoplastic -- Resistance to ozone cracking -- Test methods for determining the ozone concentration in laboratory test chambers
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GB/T 35804-2018
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Basic data | Standard ID | GB/T 35804-2018 (GB/T35804-2018) | | Description (Translated English) | Rubber, vulcanized or thermoplastic -- Resistance to ozone cracking -- Test methods for determining the ozone concentration in laboratory test chambers | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | G40 | | Classification of International Standard | 83.060 | | Word Count Estimation | 22,260 | | Date of Issue | 2018-02-06 | | Date of Implementation | 2018-09-01 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 35804-2018: Rubber, vulcanized or thermoplastic -- Resistance to ozone cracking -- Test methods for determining the ozone concentration in laboratory test chambers
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Rubber, vulcanized and thermoplastic--Resistance to ozone cracking--Test methods for determining the ozone concentration in laboratory test chambers
ICS 83.060
G40
National Standards of People's Republic of China
Vulcanized rubber or thermoplastic rubber resistant to ozone cracking
Test method for determining ozone concentration in test chamber
Rubber, vulcanizedorthermoplastic-Resistancetoozonecracking-Test
(ISO 1431-3.2000, Rubber, vulcanizedorthermoplastic-Resistancetoozone
cracking-Part 3.Referenceandalternativemethodsfordeterminingthe
Ozoneconcentrationinlaboratorytestchambers, IDT)
Published on.2018-02-06
2018-09-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard uses the translation method equivalent to ISO 1431-3.2000 "vulcanized rubber or thermoplastic rubber ozone cracking part 3.
Reference and optional test methods for determining the concentration of ozone in the test chamber.
The documents of our country that have a consistent correspondence with the international documents referenced in this standard are as follows.
---GB/T 7762-2014 Vulcanized rubber or thermoplastic rubber ozone crack resistance static tensile test (ISO 1431-1.
2004, NEQ)
---GB/T 13642-2015 Vulcanized rubber or thermoplastic rubber ozone crack resistance dynamic tensile test (ISO 1431-1.
2004, NEQ)
This standard has been edited as follows.
For ease of use, change the standard name to the test for ozone concentration in the test chamber for vulcanized rubber or thermoplastic rubber.
Method of inspection.
This standard was proposed by the China Petroleum and Chemical Industry Federation.
This standard is under the jurisdiction of the National Rubber and Rubber Products Standardization Technical Committee (SAC/TC35).
This standard was drafted. Guangzhou Synthetic Materials Research Institute Co., Ltd., Shandong Linglong Tire Co., Ltd., Beijing Rubber Industry Research
Design Institute, Fengshen Tire Co., Ltd., Anhui Jiatong Passenger Radial Tire Co., Ltd., Triangle Tire Co., Ltd., Yiwei Yi Rubber
Rubber Research Institute Co., Ltd., Guizhou Tire Co., Ltd., High Speed Rail Testing Instrument Co., Ltd., Jiangsu Mingzhu Testing Machinery Co., Ltd.
The main drafters of this standard. Liu Xiaodan, Yi Jun, Yan Dewen, Chen Shaomei, Xie Junfang, Li Jing, Ren Shaowen, Ma Tiancheng, Yu Yuan, Wu Haibin,
Yan Fujiang, Ni Shujie, Liu Aiqin, Guo Heying, Lu Qiang, Wang Lizhen, Wang Peng, Liao Wenjie, Zhu Muzhi.
Introduction
There are several methods for analyzing ozone-air mixed gas in rubber ozone cracking test, including wet chemical method, electrochemical method, and purple
External absorption method and ethylene chemiluminescence method.
In principle, wet chemical methods, electrochemical methods, and ultraviolet absorption methods are absolute methods, but in practice these methods are usually
The same test results could not be obtained.
The wet chemical method is a traditional test method used in the rubber industry and national standards to absorb ozone with potassium iodide solution, and then
The iodine element produced by the reaction was titrated with sodium thiosulfate. Wet chemical methods are not suitable for continuous operation or control, so wet chemistry in practical applications
The method is not as convenient as the instrumental analysis method. The test results show that the wet chemical method has small changes in the test procedure, the concentration of the reagent and the purity.
The degree is very sensitive and there is considerable controversy over the stoichiometry of the reaction.
Electrochemical methods are widely used in the rubber industry and are very convenient for continuous monitoring of ozone. Chemiluminescence is also widely used in rubber
Glue industry.
Recently, UV absorption analyzers have become more and more widely used, and they also have continuous monitoring capabilities. More importantly, all key environmental protection machines
The UV absorption analysis method is adopted as the standard, and the results of the ultraviolet analysis method are considered to be reliable.
Therefore, other methods are calibrated using this standard UV absorption method as a reference method. Like all other inspection equipment, UV
The accuracy of the absorption analyzer depends on the calibration and maintenance of its components, so the UV absorption analyzer is also calibrated using known standard equipment.
Several countries are conducting research and proposing the establishment of benchmark equipment.
Although this standard is mainly for ozone analysis, it also focuses on atmospheric pressure on rubber at constant ozone concentration (usually in volume fraction table).
Show) the effect of crack rate. Inter-laboratory testing between North American laboratories shows interlaboratory testing at atmospheric pressures with significant differences
The difference in the test results can be corrected by specifying the partial pressure of the ozone concentration (see Appendix A).
It must be noted that ozone is highly toxic. Measures need to be taken to reduce the exposure of test personnel to ozone. No stricter or no violation of the country
In the case of home safety regulations, it is generally considered that the maximum ozone concentration that the human body can reach is 10 pphm, and the maximum average ozone that needs to be in contact with the human body.
The concentration is below the maximum allowable concentration.
If you are not using a fully enclosed system, it is recommended to exclude ozone-containing air through the exhaust vents.
Vulcanized rubber or thermoplastic rubber resistant to ozone cracking
Test method for determining ozone concentration in test chamber
Warning. Personnel using this standard should have hands-on experience in formal laboratory work. This standard does not address all possible security issues.
It is the responsibility of the user to take appropriate safety and health measures and to ensure compliance with the conditions set by the relevant national regulations.
1 Scope
This standard specifies three methods for determining the concentration of ozone in a test chamber.
Method A - UV Absorption. This method is a baseline method for calibration of Method B and Method C.
Method B---Instrument analysis method.
B1. electrochemical method;
B2. Chemiluminescence method.
Method C---wet chemical method.
Program I;
Procedure II;
Procedure III.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
Vulcanized rubber or thermoplastic rubber - Ozone cracking - Part 1 . Static tensile test (Rubber, vul-
canizedorthermoplastic-Resistancetoozonecracking-Part 1.Staticstraintest)
Vulcanized rubber or thermoplastic rubber - Ozone cracking - Part 2. Dynamic tensile test (Rubber, vul-
canizedorthermoplastic-Resistancetoozonecracking-Part 2.Dynamicstraintest)
ISO 13964.1998 Air quality - Determination of ozone in air - Ultraviolet spectrophotometric method (Airquality-Determina-
tionofozoneinambientair-Ultravioletphotometricmethod)
3 Principle
Extraction of ozone-air mixture from an ozone chamber, analysis by instruments using UV absorption or UV-assisted calibration
Method or chemical analysis method to determine the ozone concentration.
4 equipment
The equipment for determining the ozone concentration is as follows.
---UV absorber;
---Electrochemical device;
---Chemistometer;
--- Wet chemical device.
The UV absorption method is the baseline method and all equipment should be calibrated by UV absorption according to the requirements of Chapter 5.
The equipment used for the UV absorption method shall be in accordance with ISO 13964.1998, unless the equipment used is capable of measuring ISO 1431-1.1989 and
The ozone concentration specified in ISO 1431-2.1994.
Descriptions of other methods are given in Appendix B (Instrumental Analysis Methods) and Appendix C (Wet Chemical Methods).
5 calibration
Calibration of equipment for determining ozone concentration shall be in accordance with ISO 13964.1998.
6 procedures
The ultraviolet absorption method is carried out in accordance with the provisions of ISO 13964.1998.
Other instrumental analysis methods should be carried out in accordance with the manufacturer's instructions, paying special attention to the initial setup, zeroing, and dimensioning in accordance with Appendix B.
Protection and calibration equipment.
Wet chemical methods should be carried out in accordance with Appendix C.
7 results indicate
In general, the ozone concentration φO3 is expressed in parts per volume of ozone in the air (pphm).
However, the ozone concentration can also be expressed in milligrams per cubic meter (mg/m3) or millipascals (mPa). Mg/m3 means cause within unit volume
The number of ozone molecules cracked by ozone is related to pressure and temperature.
The following equations are used for unit conversion.
φO3[mg/m3]=5.78×10-3×
T ×φO3
[pphm] (1)
In the formula.
p---atmospheric pressure in units of hectopascals (hPa);
T---temperature, the unit is Kelvin (K).
For ozone partial pressure.
pO3[mPa]=10-3pφO3[pphm] (2)
In the formula.
p---atmospheric pressure in units of hectopascals (hPa);
At 1013 hPa and 273 K, 1 pphm = 1.01 mPa.
8 test report
The test report should include the following.
a) the name and number of this standard;
b) the method used (instrumental analysis method or wet chemical method);
c) If the measurement is not continuous, indicate the measurement interval;
d) the range of ozone concentration or measured concentration, expressed in pphm or mg/m3 or mPa ozone partial pressure, if necessary corrected by a correction factor;
e) Test date.
Appendix A
(normative appendix)
Influence of ambient atmospheric pressure on rubber ozone pressure
The rate of reaction between ozone and rubber, ie the rate of cracking, is a function of the rate of collision of ozone molecules with the surface of the rubber and is therefore constant in other factors.
Timing, the crack rate is a function of the number of ozone molecules.
According to the ideal gas equation and Dalton's law, the temperature is T, and the ozone-air mixture gas volume is V, the ozone partial pressure
pO3 is a function of the mole number of ozone nO3.
pO3=nO3
RT
(A.1)
In the formula.
pO3---Ozone partial pressure in millipascals (mPa);
R --- gas constant (R = 8.314Pa · m3 · mol -1 · K-1);
T --- temperature in Kelvin (K);
V --- Ozone - air mixture volume in cubic meters (m3).
Note. At standard temperature (273K) and pressure (1 atm, 760 tor or 1013 hPa), 1 pphm = 1.01 mPa.
The formula shows that when the ozone-air mixture contains the same volume of ozone, the ozone is at the same temperature and the atmospheric pressure is different.
The partial pressure and the number of moles of ozone vary in proportion to the atmospheric pressure.
The interlaboratory test results conducted in North America demonstrate the effect of atmospheric pressure on the cracking rate under constant volumetric ozone conditions.
Therefore, when there is a difference in atmospheric pressure, it is not appropriate to express the ozone concentration in the test chamber by volume.
The effect of atmospheric pressure on ozone cracking can be tested by changing the pressure in a constant test chamber or changing the ozone-air mixture
The volume of ozone in the volume (inversely proportional to atmospheric pressure) is eliminated. The effect of atmospheric pressure on ozone cracking can also be achieved by mixing ozone-air
The concentration of ozone in the gas is eliminated by the representation of ozone partial pressure.
Appendix B
(normative appendix)
Instrumental analysis method
B.1 Electrochemical method
B.1.1 Principle
The ozone-air mixture gas is bubbled into the coulometric cell [1] at a constant rate. The coulombic cell consists of a platinum electrode (cathode) and a silver electrode (recommended).
Or a mercury iodide (anode) composed of a potassium iodide buffer solution.
Ozone reacts with potassium iodide to form free iodine. Free iodine produces electrons at the cathode to generate iodide ions, and iodide ions migrate to the anode to form iodine.
Mercury or mercury iodide. Each ozone molecule produces two unit charges, and the total current is proportional to the ozone concentration. The net electromotive force of the battery is applied
The added back EMF is offset and can be corrected by temperature and pressure.
The stoichiometry is as follows.
O3 2KI H2O=2KOH O2 I2
Cathodic reaction. I2 2e=2I-
Anode reaction. 2I--2e 2Hg=Hg2I2
According to Faraday's law.
O3→2I-→2e→2×96500 Coulomb
B.1.2 device
The analyzer should have a coulomb pool as shown in Figure B.1. Standard modules are commercially available.
The cathode is a platinum frame in which an ozone-air mixed gas can be bubbled. The anode can be of the following type, it is recommended to use b) as the anode.
a) a pool of mercury;
b) Silver spiral net.
The free iodine formed by the reaction of ozone with the solution gives electrons at the cathode and migrates to the anode as the liquid flows due to bubbling. At the anode,
The formation of insoluble silver iodide or mercury iodide produces an ionic charge equivalent to the ozone content of the incoming air stream.
As shown in Figure B.2, the battery should be connected to the analyzer's circuit.
When the ozone-free air passes through the battery, a stable DC power supply provides the opposite standard electromotive force across the battery. Standard electromotive force
The anode material is determined.
B.1.3 Reagents
Prepare a potassium iodide buffer solution as follows.
Weigh the following analytical grade chemicals and dissolve in 1 L of distilled water containing no chlorine or sulfur.
Potassium iodide (KI) 1.50g
Disodium hydrogen phosphate (Na2HPO4) 1.50g
Potassium dihydrogen phosphate (KH2PO4) 1.40g
A buffer solution having a pH of 6.5 to 6.8 can be produced.
B.1.4 Battery calibration
Assuming an air flow of 150 cm3/min at a standard temperature and atmospheric pressure and an ozone content of 100 pphm, the current is.
100×10-8×150×2×96500×106
22400×60 =
21.54μA
Therefore, in the typical circuit shown in Figure B.2, the analyzer can be calibrated directly by the correlation of current and ozone concentration.
B.2 Chemiluminescence method
In a chemiluminometer, ozonized air is introduced into a chamber and mixed with ethylene gas, and the two gases undergo a chemiluminescence reaction.
The photons are excited at 430 nm, and the excitation energy is measured by a photomultiplier tube and converted into a current output which is proportional to the concentration of ozone.
Description.
1---air-ozone mixed gas;
2---air;
3---cathode;
4---anode;
5---solution;
6---to the waste tank.
Figure B.1 Analyzer
Description.
1---microamperometer;
2---stable DC power supply;
3---electrode.
Figure B.2 Simple Analyzer Circuit
Appendix C
(normative appendix)
Wet chemical method
C.1 Basic principles
C.1.1 Neutral potassium iodide buffer solution absorbs ozone and undergoes oxidation to form free iodine.
O3 2KI H2O=2KOH O2 I2
Before the ozone is absorbed, the sodium thiosulfate solution is added to the potassium iodide solution, and the generated free iodine and thiosulfate ions are immediately generated.
reaction.
I2 2Na2S2O3=Na2S4O6 2NaI
Therefore 1 mol of ozone molecule is equivalent to 2 mol of Na2S2O3.
C.1.2 Three, I, II, and III alternative methods can be used.
C.1.2.1 Procedure I is a mature method in which a potassium iodide buffer solution containing excess sodium thiosulfate absorbs ozone,
After a fixed period of time, the excess sodium thiosulfate was titrated to the electrochemical end point using a standard I2 solution according to the usual method.
C.1.2.2 Procedure II is an improvement to Procedure I, using a recorder to monitor the voltage across the electrodes of the electrochemical endpoint detection device. Buffer to KI
Add a smaller amount of sodium thiosulfate (more dilute solution) to the solution, so that the buffer solution absorbs ozone until the sodium thiosulfate is completely consumed.
At the time, the voltage rises sharply. The end point of the reaction can be easily determined by recording the chart and the ozone concentration is calculated.
C.1.2.3 Procedure III is another variation that uses a constant current electrolytic cell device and an electrochemical endpoint.
C.2 Procedure I
C.2.1 reagent
C.2.1.1 potassium iodide buffer solution
Potassium iodide and 0.1 mol/L phosphate buffer solution were prepared. The following materials were dissolved in 1 L of distilled water to prepare a solution.
17.8g of disodium hydrogen phosphate dihydrate crystal or an equivalent amount of disodium hydrogen phosphate monohydrate crystal;
13.6 g of potassium dihydrogen phosphate (KH2PO4);
30 g ± 2 g of potassium iodide (KI).
The pH of the solution was 6.8. When using this solution, first check if there is free iodine in the solution, take 10mL buffer solution, add the number
2 mol/L HCl and 0.5 mL starch paste were dropped to confirm that there was no color change. Put the prepared solution into a brown bottle with a stopper, overcast
Keep away from light and cool.
C.2.1.2 sodium thiosulfate solution, c(Na2S2O3)=0.1mol/L
The sodium thiosulfate solution can be prepared by yourself or by using a commercially available standard solution, and stored in a cool place in the dark.
C.2.1.3 sodium thiosulfate solution, c(Na2S2O3)=0.002mol/L
On the day of the analysis, an appropriate amount of distilled water was added to a 0.1 mol/L solution to prepare a solution of 0.002 mol/L. For example, take 5mL
A solution having a concentration of 0.1 mol/L was added to a 250 mL volumetric flask, and fresh distilled water was added to the mark position.
C.2.1.4 iodine solution, c(
2I2
)=0.1mol/L
The iodine solution can be prepared by yourself or with a commercially available standard solution, and stored in a cool place in the dark.
C.2.1.5 iodine solution, c 12I2
÷=0.002mol/L
According to the method of C.2.1.3, a solution of C.2.1.4 was used to prepare a 0.002 mol/L iodine solution.
C.2.2 Instruments and equipment
C.2.2.1 Equipment for the preparation of reagents
C.2.2.1.1 Volumetric flasks, 250 mL and 1000 mL.
C.2.2.1.2 Pipette, 5 mL.
C.2.2.1.3 Balance, accurate to 5mg.
C.2.2.2 Ozone absorption device
Materials that are exposed to ozone-air mixtures should not absorb ozone significantly. All glass equipment should be exposed to ozone before use.
hour. The connecting pipe should be as short as possible and not less than 4 mm in diameter. If it is unavoidable, the connecting pipe should have as little contact as possible with ozone.
area.
C.2.2.2.1 Two 100mL gas absorption glass bottles, connected according to Figure C.1.
Warning. Do not use a fritted glass bubbler as it may interfere with the measurement.
C.2.2.2.2 Flowmeter, accurate to 1%.
C.2.2.2.3 Thermometer with a graduation of 0.5 °C.
C.2.2.3 Titration device
C.2.2.3.1 Measuring bottle, 100mL.
C.2.2.3.2 Pipette, 2 mL.
C.2.2.3.3 Burette, 2mL, accurate to 0.005mL.
C.2.2.3.4 Beaker, 250mL.
C.2.2.3.5 Measuring cylinder, 100 mL.
C.2.2.4 End point detection loop (see Figure C.2)
C.2.2.4.1 The double platinum electrode has a diameter of 2.5 mm and a length of 25 mm and is fixed in a glass conduit with a wire connection point. Do not
It is two separate electrodes, but a pair of electrodes (two electrodes) that are fixed together and slightly separated from each other. In the latter procedure, the electrode
It has a diameter of 1 mm and a length of 6 mm. At the end of each electrode is a sphere of 1.5 mm diameter. The distance between the two balls is
0.7mm. If the surface area of the two electrodes used is smaller, the sensitivity of the microamperometer used should be at least 10 times higher.
C.2.2.4.2 Microamperometry, ranging from 0μA to 20μA.
C.2.2.4.3 Two resistors connected in series, one is a variable resistor, which can be changed to 1000Ω; the other is a fixed resistor, the resistance value
It is 30,000 Ω.
C.2.2.4.4 Battery, 1.5V.
C.2.3 Procedure
C.2.3.1 Ozone absorption
A volume of ozone-air mixture is introduced into the two series of absorption bottles, each containing approximately 100 mL of iodine
The potassium buffer solution and an accurate.200 mL of a sodium thiosulfate solution having a concentration of 0.002 mol/L. The rate of gas passage should be 1L/min
Between 3L/min and the passage time should be no less than 10min. Record time, accurate to ±1s.
C.2.3.2 titration
Pour the solution from the two absorption vials into the beaker. The remaining sodium thiosulfate was titrated with a 0.002 mol/L iodine solution according to C.2.3.3.
The description uses the endpoint indication method.
C.2.3.3 End point indication
When there is excess sodium thiosulfate in the potassium iodide buffer solution, the two electrodes immersed in the buffer solution maintain a lower
Potential difference. The electrodes are polarized and have a very small amount of current through the ammeter. When the added iodine no longer reacts, it means sodium thiosulfate in the solution.
It has been consumed and the cathode is depolarized to produce a large current. A sudden change in the ammeter hand indicates that the end point has been reached.
C.2.3.4 Blank test
A blank test was carried out in full accordance with the methods of C.2.3.1 to C.2.3.3, and normal air was introduced into the absorption bottle during the test.
C.2.4 Results representation
The ozone concentration is calculated using the formula (C.1), and the ozone concentration φO3 (parts of ozone in the air per 108 volumes of air) is expressed in pphm.
φO3=
5×105×(Vb-Va)×c×R×T
p×F×t
(C.1)
In the formula.
Vb---the volume of the iodine solution used in the blank test, in milliliters (mL);
Va --- the volume of the iodine solution used in the actual measurement, in milliliters (mL);
c --- iodine solution concentration in mol/liter (mol/L);
R --- gas constant (8.314Pa·m3·mol-1·K-1);
T --- ozone-air mixture gas temperature in Kelvin (K);
p --- the air pressure at the time of input; the unit is in hundred hectopascals (hPa);
F ---Ozone-air mixture gas flow rate in liters per minute (L/min);
t --- The time in which the ozone-air mixture passes through the absorption bottle in minutes (min).
C.3 Procedure II
C.3.1 Reagent preparation
C.3.1.1 potassium iodide buffer solution
See C.2.1.1 for this solution.
C.3.1.2 sodium thiosulfate standard solution
On the day of the test, the sodium thiosulfate standard solution was diluted with the specified 0.1 mol/L solution (see C.2.1.2).
The concentration of the standard solution required is related to the ozone concentration. The appropriate concentrations are as follows.
When the ozone concentration is 25 pphm, the standard solution concentration is 0.0001 mol/L;
When the ozone concentration is 50 pphm, the standard solution concentration is 0.0002 mol/L;
When the ozone concentration is 100 pphm, the standard solution concentration is 0.0005 mol/L;
When the ozone concentration is.200 pphm, the standard solution concentration is 0.001 mol/L.
When diluting the solution with distilled water, it can be done in one or two steps using a pipette and a standard volumetric flask.
C.3.2 Equipment
C.3.2.1 Equipment for the preparation of reagents
See C.2.2.1 for basic requirements.
C.3.2.2 Ozone absorption device
See C.2.2.2 for basic requirements.
Figure C.3 is a schematic diagram of the device. Figure C.4 is the absorption bottle. If you do not have such an absorption bottle, you can use a 250 mL three-neck flask. Suck
The bottle is placed on a magnetic stirrer. Insert a pair of platinum electrodes or two electrodes into the absorption bottle, the electrodes are connected to the recorder, and the recorder is full scale
It is 50mV or 100mV. The drawing speed is applied to the stopwatch check.
C.3.3 Procedure
C.3.3.1 Through the branch, the flow rate of the ozone/air mixture gas is adjusted to 1 L/min.
C.3.3.2 Add about 60 mL of potassium iodide buffer solution to the absorption bottle, and accurately add 5 mL of standard thios to the absorption bottle with a pipette.
Sodium sulfate solution. Start stirring and recording vigorously, and the recording speed is preferably 10 mm/min.
C...
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