1、BSI Standards PublicationBS ISO 18852:2015Rubber compoundingingredients Determinationof multipoint nitrogen surfacearea (NSA) and statisticalthickness surface area (STSA)BS ISO 18852:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18852:2015. Itsupersedes
2、BS ISO 18852:2012 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/50, Rubber - Raw, natural and synthetic, includinglatex and carbon black.A list of organizations represented on this committee can beobtained on request to its secretary.This publicat
3、ion does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 86472 8ICS 83.040.20Compliance with a British Standard cannot confer immunity from
4、legal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 June 2015.Amendments issued since publicationDate Text affectedBS ISO 18852:2015 ISO 2015Rubber compounding ingredients Determination of multipoint nitrogen surface area (NSA
5、) and statistical thickness surface area (STSA)Ingrdients de mlange du caoutchouc Dtermination de la surface par adsorption dazote (NSA) et de la surface par paisseur statistique (STSA) par mthode multipointsINTERNATIONAL STANDARDISO18852Third edition2015-06-01Reference numberISO 18852:2015(E)BS ISO
6、 18852:2015ISO 18852:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posti
7、ng on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightis
8、o.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 18852:2015ISO 18852:2015(E)Foreword iv1 Scope . 12 Normative references 13 Principle 14 Apparatus . 15 Reagents 36 Preparation of automatic volumetric adsorption measurement apparatus . 37 Sample preparation . 37.1 General . 37.2 Vacuum suction meth
9、od . 37.3 Purge gas flow method . 48 Measurement procedure 58.1 Measurement 58.2 Selection of data points and determination of nitrogen surface area (NSA) . 58.2.1 General 58.2.2 Procedure A 58.2.3 Procedure B 68.3 Verification of measured values . 69 Determination of statistical thickness surface a
10、rea (STSA) 69.1 General . 69.2 Procedure 79.3 Calculation of STSA 79.4 Verification of measured values . 710 Precision . 711 Test report . 7Annex A (informative) Precision . 8Bibliography .10 ISO 2015 All rights reserved iiiContents PageBS ISO 18852:2015ISO 18852:2015(E)ForewordISO (the Internationa
11、l Organization for 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 es
12、tablished has the right 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 standardi
13、zation.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance w
14、ith the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).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. Details of any
15、 patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.
16、For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible fo
17、r this document is ISO/TC 45, Rubber and rubber products, Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry.This third edition cancels and replaces the second edition (ISO 18852:2012), which has been technically revised with the following changes: Clause 6: deletion o
18、f the description of what operators do not have to do; specification of what operators have to do. The verification of measured values was moved to Clause 8 for measurement procedure; Clauses 7 and 10: addition of explanations for operators to carry out the procedure easily; Clause 8: the descriptio
19、n for selecting data points has been modified; the specification of sample mass has been moved to Clause 7 for sample preparation, and the previous Clause 9 was deleted.iv ISO 2015 All rights reservedBS ISO 18852:2015Rubber compounding ingredients Determination of multipoint nitrogen surface area (N
20、SA) and statistical thickness surface area (STSA)WARNING Persons using this International Standard should be familiar with normal laboratory practice. This International Standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the
21、user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.1 ScopeThis International Standard specifies a method for the determination of the nitrogen surface area (NSA) of carbon blacks and other rubber compounding ingredients, like si
22、licas and zinc oxides, based on the Brunauer, Emmett and Teller (BET) theory of gas adsorption using a multipoint determination as well as the determination of the statistical thickness surface area (STSA), otherwise known as the external surface area. STSA, however, is not applicable to silica and
23、zinc oxide.The method can also be used for verifying “single-point” procedures described in ISO 4652 and other standards.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, on
24、ly the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 4652:2012, Rubber compounding ingredients Carbon black Determination of specific surface area by nitrogen adsorption methods Single-point proceduresISO 5794-1:20
25、10, Rubber compounding ingredients Silica, precipitated, hydrated Part 1: Non-rubber tests3 PrincipleA sample of carbon black, silica, zinc oxide, etc., is placed in a cell of known volume and degassed. Known volume of nitrogen gas is dosed into the cell that is kept at the temperature of liquid nit
26、rogen. The pressure in the cell decreases to the equilibrium due to the adsorption by the sample. The adsorbed amount at the equilibrium is derived from the difference between the amount of the dosed gas and that of remainder in the cell. The pressure is measured together with the temperature in the
27、 system, and the volume of the system is measured with a gas that does not adsorb such as helium before the test. NSA is determined by the BET analysis on the adsorption amount obtained, and STSA is determined by t-plot analysis.4 Apparatus4.1 Automatic volumetric adsorption measurement apparatus, c
28、onsisting of a pressure gauge or transducer, a calibration volume, a Dewar flask and all other accessories required for the analysis.The pressure gauge or transducer shall have the 0,25 % accuracy of full scale at the range from 0 kPa to 133 kPa.Calibration volume is where the volume of the nitrogen
29、 to be adsorbed is measured and shall have a known internal volume with a valve or stopcock. It shall have been calibrated by its manufacturer prior to testing.INTERNATIONAL STANDARD ISO 18852:2015(E) ISO 2015 All rights reserved 1BS ISO 18852:2015ISO 18852:2015(E)Sample port volume is where the ads
30、orption to samples takes place, and the pressure at adsorption equilibrium described in Clause 3 is the pressure of this part. A connector connects the apparatus with an adsorption cell.NOTE Commercially, there are two types of the apparatus with different calibration method for the volume of the ad
31、sorption cell; those which a calibration factor is applied to the volume of the blank cell determined prior to testing, and those which the volume of the cell with a sample is directly measured during testing (with or without parallel measurement of the volume of another blank cell). Either type is
32、suitable.4.2 Adsorption cell (hereinafter called “cell”), made of glass and capable of maintaining a vacuum at a pressure 2,7 Pa or below when connected to the adsorption apparatus.A stopper or valve needs to be attached in order to avoid adsorption after drying.4.3 Analytical balance, with 0,1 mg s
33、ensitivity.4.4 Degassing station and heating mantle, capable of maintaining the temperatures in Table 1 together with vacuum suction or purge gas flow in order to perform degassing procedure specified in Clause 7.Key1 pressure gauge or transducer 6 connector2 calibration volume 7 adsorption cell3 ga
34、s dosed 8 Dewar flask4 valve 9 to vacuum pump5 sample port volumeFigure 1 Diagram of adsorption measurement apparatus2 ISO 2015 All rights reservedBS ISO 18852:2015ISO 18852:2015(E)5 Reagents5.1 Liquid nitrogen, 99,9 % or higher purity.5.2 Ultra-high-purity nitrogen gas, 99,995 % or higher purity.5.
35、3 Ultra-high-purity helium gas, 99,99 % or higher purity.NOTE Helium is used for the calibration of the volume of the automatic volumetric adsorption measurement apparatus since it does not adsorb to the cell or sample.6 Preparation of automatic volumetric adsorption measurement apparatus6.1 Turn on
36、 the automatic volumetric adsorption measurement apparatus and computer.6.2 Connect the cylinders of helium and nitrogen to the automatic volumetric adsorption measurement apparatus with gas tubes, and check if the secondary pressure of the regulator is as specified by the manufacturer of the appara
37、tus.6.3 Check if there is no leakage between the connected tubes.6.4 Carry out gas purging for the tubes to the apparatus when the cylinders are replaced or the apparatus is not used for a month or longer.6.5 Verify periodically that the error sources in the apparatus have been appropriately minimis
38、ed in accordance with the users manual.7 Sample preparation7.1 GeneralPrior to the determination of NSA or STSA, adsorbed contaminants such as atmospheric molecules shall be removed from the sample surface (= degassing). The degassing conditions vary by the material measured and shall be as given in
39、 Table 1.Table 1 Degassing conditionMaterial TemperatureCTime, minimumhReferenceCarbon black 300 10 0,5 ISO 4652-1:2012, 3.6.1.2, 4.4, 5.5.6, 6.7.4, and 6.7.5Silica 155 5 1,0 ISO 5794-1:2010, D.4.6 and E.3.2Zinc oxide (Type A or B) a300 10 0,5Zinc oxide (Type C)a155 5 1,0 ISO 5794-1:2010, D.4.6aThe
40、various zinc oxide grades are listed in Table D.1 of ISO 9298:1995.7.2 Vacuum suction method7.2.1 After degassing a blank cell by vacuum suction, fill the cell with nitrogen gas (5.2) or helium gas (5.3) of atmospheric pressure. Insert a glass rod into the adsorption cell stem, if recommended by the
41、 ISO 2015 All rights reserved 3BS ISO 18852:2015ISO 18852:2015(E)manufacturer of the apparatus, to reduce the dead volume. Disconnect the cell from the adapter and promptly seal it with a stopper or valve. Weigh the cell to the nearest 0,1 mg and record the mass m1.7.2.2 Weigh a sample dried in adva
42、nce so that the NSA of the sample is equivalent to 20 m2to 50 m2, and put it in the cell. Drop the sample clinging on the cell stem into the cell with a pipe cleaner.7.2.3 Connect the cell containing a sample to the degassing station and degas under vacuum suction with heating in accordance with the
43、 operating instructions.7.2.4 After degassing, fill the cell with the gas, of atmospheric pressure, used in 7.2.1. Disconnect the cell from the adapter and promptly seal it with a stopper or valve. Weigh the cell to the nearest 0,1 mg and record the mass m2.7.2.5 Calculate the sample mass as follows
44、:mmm021= (1)wherem0is the sample mass, expressed in grams;m2is the mass of the cell, glass rod, gas in the cell, sample and stopper or valve, expressed in grams;m1is the mass of the cell, glass rod, gas in the cell and stopper or valve, expressed in grams.7.3 Purge gas flow method7.3.1 Connect a bla
45、nk cell to the adapter and open the valve connected to the cell. Insert a gas tube for nitrogen gas (5.2) or helium gas (5.3) to the bottom of the cell and fill the cell with the gas. Disconnect the cell from the adapter and promptly seal it with a stopper or valve. Weigh the cell to the nearest 0,1
46、 mg and record the mass m1.7.3.2 Weigh a sample dried in advance so that the NSA of the sample is equivalent to 20 m2to 50 m2, and put it in the cell. Drop the sample clinging on the cell stem into the cell with a pipe cleaner.7.3.3 Connect the cell containing a sample to the adapter and open the va
47、lve connected to the cell. Insert the gas tube used in 7.3.1 again to the bottom of the cell and apply an appropriate amount of gas flow so that the sample is not stirred up. While applying the gas, heat the sample in accordance with a condition in Table 1 until the mass becomes constant.The degassi
48、ng time might vary significantly from sample to sample, and a reasonable margin of excess time is recommended.7.3.4 After degassing, disconnect the cell from the adapter and promptly seal it with a stopper or valve. Weigh the cell to the nearest 0,1 mg and record the mass m2.7.3.5 Calculate the samp
49、le mass m0as given in 7.2.5.4 ISO 2015 All rights reservedBS ISO 18852:2015ISO 18852:2015(E)8 Measurement procedure8.1 Measurement8.1.1 Since most of the operations are conducted automatically, it is important to become thoroughly familiar with the procedures and to follow carefully the operating instructions.8.1.2 Determine the saturation vapour pressure of the liquid nitrogen (5.1) in a Dewar flask by measuring its temperature. This pressure is affected by the purity of the liquid nitrogen and the ambient pressur
