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1、STD-IS0 30L1-ENGL 1785 D 4853703 0753787 Tb3 INTERNATIONAL STANDARD IS0 304:1985 TECHNICAL CORRIGENDUM 1 Published 1998-07-01 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXIIYHAPOIIHAR OPrAHM3AUMR il0 CTAHllAPTM3AUMM * ORGANISATION INTERNATIONALE DE NORMALISATION Surface active agents - Determin
2、ation of surface tension by drawing up liquid films TECHNICAL CORRIGENDUM 1 Agents de surface - Dtermination de la tension superficielle par tirement de films liquides RECTIFICATIF TECHNIQUE i Technical Corrigendum 1 to International Standard IS0 304:1985 was prepared by IS0 Central Secretariat on b
3、ehalf of Technical Committee ISO/TC 91, Surface active agents. This material is reproduced from IC0 documents under International Organization for Standardization (ICO) Copyright License number IHCllCC11996. Not for resale. No part of these IC0 documents may be reproduced in any form, electronic ret
4、rieval system or otherwise, except as allowed in the copyright law of the country of use, or with the prior written consent of IC0 (Case postale 56,1211 Geneva 20, Switzerland, Fax +41 22 734 10 79), IHC or the IC0 Licensors members. Page 1 Clause O Delete the last sentence. Page 2 6.1.1 In line 4,
5、replace “see sub-clause 5.2 of IS0 2456” by “complying with the requirements of clause 4 of IS0 2456”. 6.2.1 In the last line of the second paragraph, replace “sub-clause 5.2 of IS0 2456” by “clause 5 of IS0 2456”. ICs 71.100.40 Ref. No. IS0 304:1985/Cor.l:1998(E) Descriptors: surfactants, tests, de
6、termination, surface tension. Q IS01998 Printed in Switzerland COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services International Standard 304 INTERNATIONA
7、L ORGANIZATION FOR STANOAROIZATIONWAEYHAPO/IHAfl OPAHM3AWlfl il0 CTAHAAPTM3Al(MMWRGANiSATiON INTERNATIONALE OE NORMALISATION - UDC 661.185:532.61.08 Ref. No. IS0 304-1985 (E) ! 2 8 Descriptors : surfactants, tests, determination, surface tension. $ F) i Surface active agents - Determination of surfa
8、ce tension by drawing up liquid films Agents de surface - Dtermination de la tension superficielle par tirement de films liquides Second edition - 1985-12-15 Price based on 10 pages - COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT Interna
9、tional Organization for Standardization Licensed by Information Handling Services _ 304-85 3 4853703 O023408 7 Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards i
10、s normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee, International organizations, govern- mental and non-governmental, in liaison with ISO, also take p
11、art in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the membe
12、r bodies voting. International Standard IS0 304 was prepared by Technical Committee ISO/TC 91, Surface active agents. This second edition cancels and replaces the first edition (IS0 304-1978), of which it constitutes a minor revision. Users should note that all International Standards undergo revisi
13、on from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. O International Organization for Standardization, 1985 Printed in Switzerland COPYRIGHT International Organization for Standardization Licensed by Informat
14、ion Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services INTERNATIONAL STANDARD IS0 304-1985 (E) Surface active agents - Determination of surface tension by drawing up liquid films O Introduction Surface tension is a fundamental propert
15、y of liquids in general and aqueous solutions of surface active agents in particular. The measurement of this characteristic, however, does not allow, in the case of solutions of surface active agents, any suppositions as to their detergency, wetting, foaming, emulsi- fying activities, etc. Indeed,
16、no connection can be established between the performance properties of the surface active agents and the surface tension of their solutions. 1 This International Standard specifies a test method for the determination, by drawing up liquid films, of the surface ten- sion of aqueous or organic solutio
17、ns of surface active agents and mixtures containing one or more surface active agents. Scope and field of application It also applies to the measurement of surface tension of pure liquids or solutions other than those mentioned above. NOTE - Numerous methods have been established to determine sur- f
18、ace tension, such as : methods by drawing up liquid films by a plate, stirrup or ring; methods for measuring the rise of liquid in a capillary tube; maximum ball pressure method; drop weight method; drop or sessile ball method; suspended drop method; dynamic methods based on measurements of flow cha
19、rac- teristics: h) methods which study the waves produced in capillary jets. The methods based on drawing up liquid films have notable advan- tages in the simplicity of their procedure and the commercial availabili- ty of highly automatic appliances. 2 References IS0 862, Surace active agents - Voca
20、bulary. IS0 2456, Surface active agents - Water used as a solvent for tests. * 3 Definition surface tension : See IS0 862. NOTE - The SI unit of surface tension is the newton per metre (N/mi. In practice, the submuitiple millinewton per metre mN/m)* is used. 4 Principle Measurement of the maximum fo
21、rce which it is necessary to exert vertically on a stirrup or a ring, in contact with the surface of the liquid being examined piaced in a measuring cup, in order to separate it from this surface, or on a plate, with an edge in contact with the surface, in order to draw up the film that has formed.
22、5 Apparatus Ordinary laboratory apparatus and 5.1 and rings, and which shall comprise the following items : Tensiometer, which can be fitted with plates, stirrups a) A horizontal platform, which can be moved vertically in both directions by means of a micrometer screw. It shall be fitted with a mill
23、imetric scale allowing estimation of ver- tical movements of 0,l mm; * At present at the stage of draft. * 1 mN/m = 1 dyn/cm 1 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Infor
24、mation Handling Services -. - - - _I- 304-85 14853903 002L4l10 5 1 - IS0 304-1985 (E) b) A dynamometer, to give a continuous measure of the 6.1.2 The temperature of the solutions shall be maintained to force applied to the measuring unit with an accuracy of at within 0,5 OC. least 0 , l mN/m. NOTE -
25、 Determinations carried out in the region of points of critical c) A device for indicating or recording the values solubilitv, such as the Krafft temperature, cloud temperature of measured by the dynamometer. ethylene oxide condensates, etc., are seriously marred by errors. It is preferable to proce
26、ed at a temperature higher than that of the par- The assembly shall be shielded from vibrations and draughts, ticular points, or at a temperature lower than the cloud temperature of ethylene oxide condensates. 5.2 Measuring unit, which shall comprise at least one of the items a), b) and c) and also
27、item d). 6.1.3 As the it is difficult to recommend a standard ageing period for the sol- tension of solutions varies with a) A rectangular plate of sheet platinum, 0,l mm thick and about 30 mm long by 20 mm wide, roughened using emery paper in such a way that the strokes are perpen- dicuar to the si
28、de intended to be submerged. The plate is fixed, preferably by welding but alternatively by any other means, to a suspension rod situated in the axis of symmetry of the plate see figure 1). b) A stirrup of platinum - iridium wire of diameter not exceeding 0 , l mm; the length of the horizontal arm i
29、s 20 to 40 mm and the length of the two vertical branches is 10 mm. The ends of these branches terminate in two small platinum balls which act as counterweights see figure 2). c) A ring of platinum - iridium wire, 0,3 mm in diameter. The circumference of the ring is generally between 40 and 60 mm. I
30、t is fixed to a suspending rod by means of a platinum wire stirrup (see figure 3). di A measuring cup, to hold the test portion of the liquid to be examined, consisting of a small glass tank capable of containing a sufficient quantity of liquid. Watch-glasses shall not be used. In the case of the de
31、termination of the surface tension of sol- utions of surface active agents, cylindrical tanks with a diameter of at least 8 cm may be used. For determinations on pure liquids, the ideal measuring cup is a small tank in the form of a rectangular parallelepiped having sides of at least 8 cm; this shap
32、e enables the liquid surface to be cleaned completely by wiping. NOTE - Generally, in the case of dilute solutions of surface active agents, the surface should only be wiped if the concentration of the surface active agent is close to the critical concentration for micelle formation c.m.c.). 6 Proce
33、dure 6.1 agents 6.1.1 The solutions of surface active agents for the deter- minations shall be prepared with all necessary care. The water used for preparing them shall be double-distilled water (see sub-clause 5.2 of IS0 2456), checked by measuring its surface tension. Cork stoppers and, more parti
34、cularly, rubber stoppers, shall on no account be used, either in the construction of the distillation apparatus or for stoppering containers in which the water is kept. Preparation of solutions of surface active ution, because the nature and purity of the surface active agent, its concentration and
35、its liability to adsorption all play a particular part in these variations. It is therefore desirable to make several measurements over a period of time, to construct the surface tension curve as a function of time and to deter- mine the position of the level portion, which gives the age at which th
36、e solution has reached its equilibrium state. Automatic apparatus is very suitable for carrying out the measurements, the values being recorded as a function of the time. 6.1.4 The surface of the solutions is extremely sensitive to contamination by atmospheric dust or by vapours from solvents handle
37、d in the vicinity. Therefore no volatile products shall be handled in the room where the determinations are made and the complete apparatus shall be protected by a bell of the kind used for balances. These precautions also reduce variation in temperature. 6.1.5 The method recommended for taking the
38、test portion of the liquid examined is to suck it, with a pipette, from the centre of the mass of liquid, as the surface may be liable to soiling by insoluble particles and dust. 6.2 Cleaning the measuring unit 6.2.1 Cleaning the measuring cup In the presence of impurities such as silicones, which a
39、re not removed by sulfo-chromic acid mixture, phosphoric acid or a solution of potassium persulfate in sulfuric acid, wash the measuring cup using special products (for example toluene, perchloroethylene or methanolic potassium hydroxide solution). If these impurities are absent, or after cleaning w
40、ith these pro- ducts, wash the measuring cup carefully with hot sulfo- chromic acid mixture and then with concentrated phosphoric acid 83 to 98 % (rn/rn)l. Finally, rinse in double-distilled water until the rinsings are neutral. The double-distilled water shall be freshly prepared according to sub-c
41、lause 5.2 of IS0 2456. Before the determination, the measuring cup shall be rinsed several times with the liquid to be examined. 6.2.2 Cleaning the plate, stirrup or ring If necesSan/, clean the platinum plate, stirrup or ring (5.2) with special products as specified in 6.2.1. In the absence of im-
42、purities requiring cleaning with these products, or after clean- ing with these products, wash the platinum measuring unit 2 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Informa
43、tion Handling Services with hot concentrated sulfuric acid (pm = 1,839 g/mll and then rinse with double-distilled water until the rinsings are neutral. Plates shall never be dried by passing through a flame. Do not touch the measuring unit or the inner surface of the measuring cup with the fingers.
44、6.3 Calibrating the tensiometer 6.3.1 Principle Calibrate the tensiometer (5.1) by adjusting it so that the indica- tions or recordings of the device 1 5 . 1 c)l are expressed directly in millinewtons per metre (mN/m). 6.3.1.1 Using a plate as the measuring unit During the determination, the roughen
45、ed platinum plate l 5 . 2 a), when submerged in the liquid to be examined, is sur- rounded by a layer of liquid which wets it completely; the system behaves as if the liquid were making tangential contact with a theoretical plate consisting of the plate surrounded by its wetting sheath. Avoid lettin
46、g the plate dry completely after cleaning and before submersion in the liquid to be examined. Because of the system by which the plate is connected to the measuring apparatus, it is easy to drain the plate properly; when the plate is removed from the liquid, one end of its base comes away owing to i
47、nevitable lack of symmetry, and leaves one corner immersed. If withdrawal is continued very slowly, the required drainage conditions are obtained, and the plate is removed without bringing away any droplets. To set the apparatus to zero, it is necessary to proceed with the plate completely withdrawn
48、, the plate being drained as in- dicated-above. correction for wetting is thus included in the calibration and is not involved in the determinations. 6.3.1.2 Using a stirrup as the measuring unit In order to avoid the correction of buoyancy resultingfrom the volume of the immersed wire and the two p
49、latinum balls, first set the apparatus to zero with the stirrup 1 5 . 2 b)l immersed in a liquid of the same density as the liquid being examined, until its horizontal arm is level with the surface of the liquid. 6.3.1.3 Using a ring as the measuring unit When using a ring 5.2 c), it is not necessary to make buoy- ancy corrections. 6.3.2 Calibration procedure Calibration can be carried out by two methods : a) by means of riders of known mass, placed on the plate, stirrup or ring. The operation is lengthy, but very accurate. IS0 304-1985(E) The instrument reading, indi