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1、BRITISH STANDARD BS ISO 18852:2005 Rubber compounding ingredients Determination of multipoint nitrogen surface area (NSA) and statistical thickness surface area (STSA) ICS 83.040.20 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 18
2、852:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 1 August 2005 BSI 1 August 2005 ISBN 0 580 46233 1 National foreword This British Standard reproduces verbatim ISO 18852:2005 and implements it as the UK national standard. The UK parti
3、cipation in its preparation was entrusted to Technical Committee PRI/50, Rubber-raw, natural and synthetic, including latex and carbon black, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The Briti
4、sh Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This pub
5、lication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible internati
6、onal/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title pa
7、ge, pages ii to iv, pages 1 to 11 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled
8、Copy, (c) BSI Reference number ISO 18852:2005(E) INTERNATIONAL STANDARD ISO 18852 First edition 2005-05-15 Rubber compounding ingredients Determination of multipoint nitrogen surface area (NSA) and statistical thickness surface area (STSA) Ingrdients de mlange du caoutchouc Dtermination de la surfac
9、e par adsorption dazote (NSA) et de la surface par paisseur statistique (STSA) par mthode multipoints BS ISO 18852:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00
10、:00 2006, Uncontrolled Copy, (c) BSI BS ISO 18852:2005 iii Contents Page Foreword iv 1Scope 1 2Normative references . 1 3Principle . 2 4Apparatus. 2 5Reagents 3 6Preparation and calibration of static-volumetric apparatus.3 7Preparation of apparatus 4 8Measurement procedure 5 9Calculation of the nitr
11、ogen surface area 6 10Determination of statistical thickness surface area (STSA).7 11Precision and bias 8 12Test report 11 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 18852:2005 iv Foreword ISO (the International Organization for
12、Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the r
13、ight to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Internation
14、al Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as
15、 an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. IS
16、O 18852 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Rubber compounding ingred
17、ients Determination of multipoint nitrogen surface area (NSA) and statistical thickness surface area (STSA) WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated w
18、ith its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope This International Standard specifies a method for the determination of the nitrogen surface area (NSA) of carbon blacks an
19、d other rubber compounding ingredients, like silicas and zinc oxides, based on the Brunauer, Emmett and Teller (BET) theory of gas adsorption using a multipoint determination. This test method specifies the sample preparation and treatment, instrument calibration, required accuracy and precision of
20、the experimental data, and calculation of the surface area results from the data obtained. Also given is a procedure for calculating the statistical thickness surface area (STSA), otherwise known as the external surface area. The test method specified uses an automatic volumetric static-vacuum appar
21、atus, the surface area being calculated using the BET theory based on monolayer measurements. The method can also be used for verifying “single-point” procedures described in ISO 4652-1 and other standards. The automatic instruments described in these standards perform all the necessary computations
22、, including that of the surface area based on statistical thickness. However, the automatic point-setting procedures used are not applicable to the STSA method. NOTE Automatic instruments based on continuous flow using mixtures of nitrogen and helium gas in various ratios are also available. As good
23、 as they are, it is highly desirable to verify their accuracy of measurement against results obtained from static-vacuum-type instruments. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited ap
24、plies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 4652-1:1994, Rubber compounding ingredients Carbon black Determination of specific surface area by nitrogen adsorption methods Part 1: Single-point procedures ISO 5794-1:2005, Rubber
25、compounding ingredients Silica, precipitated, hydrated Part 1: Non-rubber tests ISO 9298:1995, Rubber compounding ingredients Zinc oxide Test methods BS ISO 18852:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 3 Principle A test port
26、ion of carbon black, silica, zinc oxide, etc, is placed in a cell of known volume and degassed. Using the ideal-gas equation, the volume of nitrogen required to give a predetermined relative pressure is calculated and dosed into the sample cell. Any additional nitrogen required to attain this relati
27、ve pressure is due to adsorption by the test portion. The amounts of nitrogen adsorbed at different relative pressures are then used to calculate the specific surface area. When analysing the various materials cited above, the following degassing conditions shall be used: Temperature Time, minimum M
28、aterial C h Reference Carbon black 300 ? 10 0,5 ISO 4652-1:1994 3.6.1.2; 4.4; 5.5.6; 6.7.4 and 6.7.5 Hydrated silica 155 ? 5 1,0 ISO 5794-1:2005 Annex D, D.4.3 Zinc oxide (type A or B) a 300 ? 10 0,5 Zinc oxide (type C)a 155 ? 5 1,0 ISO 5794-1:2005 Annex D, D.4.3 a The various zinc oxide grades are
29、listed in ISO 9298:1995 in Annex D, Table D.1. In the method described below, the degassing conditions indicated are those for carbon black, and have to be replaced by those indicated in the table for silica or zinc oxide. 4 Apparatus 4.1 Automatic static-volumetric vacuum apparatus for multipoint n
30、itrogen surface area analysis, with vacuum system, Dewar flasks and all other accessories required for the analysis. The instruments on the market are of two types: those in which the surface area of the empty sample tube is determined prior to the analysis of the test portion, thus allowing correct
31、ions for non-ideal gas behaviour to be made and sample tube correction factors to be applied, and those instruments with a reference tube, on which measurements are made in parallel with those on the sample tube, thus avoiding the need to calculate corrections of this type. Either type of instrument
32、 may, additionally, use a different procedure to determine data points: Procedure A: The points may be obtained by fully automatic metering of the injected-gas volume, the pressure equilibration parameters being chosen by the operator. The number of data points will thus be dependent on these parame
33、ters. Procedure B: A limited number of points (usually 5 or 10) may be defined at specific p/p0 values. The equilibration procedure will then aim to come as near as possible to these values. They may, for instance, be chosen to be equidistant from each other. Irrespective of the way they are obtaine
34、d, the data points used in the calculation of the regression line shall be selected from inside the p/p0 range defined below. However, results obtained with one and the same test portion may be different when the data has been acquired using different equilibration procedures. Since procedure A is m
35、ore accurate, it shall be used to verify all other methods. 4.2 Adsorption cells, which, when attached to the adsorption apparatus, can be maintained at a pressure below 1,35 mPa (10 nmHg). BS ISO 18852:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrolled
36、 Copy, (c) BSI 3 4.3 McLeod gauge, or equivalent, capable of measuring the pressure of a high vacuum. 4.4 Pressure gauge or transducer, with a reading accuracy of ? 0,25 % or ? 70 Pa (? 0,5 mmHg), covering the range 0 kPa to 135 kPa (0 mmHg to 1 000 mmHg). 4.5 Small glass vials with caps (about 30 c
37、m3), for oven-drying samples. 4.6 Analytical balance, with 0,1 mg sensitivity. 4.7 Heating mantle or degassing station, capable of maintaining a temperature of 300 C ? 10 C. 4.8 Calibration volume, consisting of a cylindrical or spherical glass (or corrosion-resistant metal) reservoir, having an int
38、ernal volume between 75 cm3 and 500 cm3, and with a valve or stopcock and a connector by which it can be connected to the sample port of the gas adsorption apparatus. 5 Reagents 5.1 Reagent-grade chemicals, conforming to the specified or recommended standards for laboratory chemicals, shall be used
39、in all tests. 5.2 Water, distilled, or of equivalent purity. 5.3 Liquid nitrogen, 98 % or higher purity. 5.4 Ultra-high-purity nitrogen gas, from a cylinder or other suitable source. 5.5 Ultra-high-purity helium gas, from a cylinder or other suitable source. 5.6 High-vacuum stopcock grease. 6 Prepar
40、ation and calibration of static-volumetric apparatus 6.1 This procedure shall be performed for the initial calibration, periodically as a quality control measure, and following repairs or adjustments. If a commercial apparatus is used, consult the users manual for specific instructions in carrying o
41、ut the steps which follow. 6.2 Attach the vacuum and pressure gauges or transducers (4.3 and 4.4) to the apparatus and evacuate it, the manifold and all internal pressure/vacuum sensors to 2,7 Pa (20 mHg) or below. 6.3 Verify that the internal vacuum sensor(s) are reading correctly and that the inte
42、rnal pressure sensor(s) are reading correctly in the vicinity of zero pressure, taking into account the expected resolution and stability limits. Make adjustments as needed. 6.4 Close the vacuum path and admit nitrogen gas to build 100 kPa ? 1 % (750 mmHg ? 7,5 mmHg) of pressure. Verify that the pre
43、ssure sensors read the correct pressure to within ? 0,25 %. Make adjustments as needed. 6.5 Thoroughly clean and dry an empty adsorption cell (4.2). Connect it to the apparatus and evacuate it to 2,7 Pa (20 mHg). Apply a 300 C heating mantle and continue evacuation for at least 1 h and until the rat
44、e of pressure rise upon temporarily closing the vacuum path is under 0,4 Pa (3 mHg) per minute. 6.6 Perform a “blank analysis” on this clean empty cell at 0,05; 0,10; 0,15; 0,20 and 0,25p/p0. Use a “p0 value” of 101,325 kPa (760 mmHg) and a “test portion mass” of 1 g for the calculations. 6.7 Examin
45、e the mean value of the “adsorbed quantities” obtained. Ideally, this should be zero. A single reading exceeding 0,25 standard cm3 makes the set-up unacceptable. As a rule, only readings below BS ISO 18852:2005 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:02:40 GMT+00:00 2006, Uncontrol
46、led Copy, (c) BSI 4 0,125 standard cm3 are acceptable although one of them may go as high as 0,25 standard cm3. A parabolic error versus pressure profile may indicate failure to correct properly for non-ideal gas behaviour or transducer linearity problems. A linear error profile indicates failure to
47、 properly measure or account for unadsorbed gas (free-space error). Erratic variation of data points indicates leaks or noisy measurements. 6.8 Determine the internal volume of the calibration-volume reservoir (4.8) below the valve or stopcock by the difference in mass when empty and then when fille
48、d completely with distilled water (5.2). Measure the water temperature and use the correct water density to obtain the exact volume of water contained. It may be necessary to immerse the device in boiling water to ensure complete filling and degassing. Repeat the procedure until the calibration volu
49、me is known to better than 0,1 %. Empty the calibration volume and thoroughly dry it overnight in the vacuum oven at 70 C ? 5 C. 6.9 Connect the calibration-volume reservoir to a sample port of the gas adsorption apparatus, open the valve or stopcock, and evacuate the reservoir to below 2,7 Pa (20 mHg). Continue evacuation for one more hour. Close off the path to the vacuum source and note whether any rise in pressure occurs. The pressure shall remain below 2,7 Pa (20 mHg), with
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