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1、A Reference number ISO 1183-3:1999(E) INTERNATIONAL STANDARD ISO 1183-3 First edition 1999-09-15 Plastics Methods for determining the density of non-cellular plastics Part 3: Gas pyknometer method Plastiques Mthodes pour dterminer la masse volumique des plastiques non alvolaires Partie 3: Mthode uti
2、lisant un pycnomtre gaz ISO 1183-3:1999(E) ISO 1999 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher
3、. International Organization for Standardization Case postale 56 CH-1211 Genve 20 Switzerland Internetisoiso.ch Printed in Switzerland ii Contents 1 Scope1 2 Terms, definitions, symbols, units and abbreviated terms.1 3 Principle2 4 Apparatus and materials.3 5 Test specimens3 6 Calibration3 7 Procedu
4、re and calculation4 8 Precision.4 9 Test report4 Annex A (informative) Two-chamber pressure-measuring pyknometer6 ISOISO 1183-3:1999(E) iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepar
5、ing 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 right to be represented on that committee. International organizations, governmental and non-governmental, in li
6、aison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft Internatio
7、nal Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 1183-3 was prepared by Technical Committee ISO/TC 61, Plastics
8、, Subcommittee SC 5, Physical-chemical properties. Together with the other parts (see below), it cancels and replaces ISO 1183:1987, which has been technically revised. ISO 1183 consists of the following parts under the general title, Plastics Methods for determining the density of non-cellular plas
9、tics: Part 1: Immersion method, pyknometer method and titration method Part 2: Density gradient column method Part 3: Gas pyknometer method Annex A of this part of ISO 1183 is for information only. ISO 1183-3:1999(E) ISO iv Introduction This part of ISO 1183 is one of a series dealing with methods o
10、f measuring the density of solid non-cellular plastics. The values obtained using this part of ISO 1183 are expected to be comparable to those obtained using the other parts. Density measurements may be used to investigate variations in the physical structure or the molecular order of materials. Suc
11、h measurements are widely used to determine the degree of crystallinity of polymers. In addition, they may be used to determine the amount of filler present. The density of a plastic material may depend on any conditioning or thermal treatment which the material has undergone. The physical structure
12、 of a polymer can change with time and temperature. Its volume is also a temperature- dependent property. This means that the density may vary with time and/or temperature. INTERNATIONAL STANDARD ISOISO 1183-3:1999(E) 1 Plastics Methods for determining the density of non-cellular plastics Part 3: Ga
13、s pyknometer method WARNING The use of this part of ISO 1183 may involve hazardous materials, operations or equipment. This part of ISO 1183 does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this part of ISO 1183 to estab
14、lish appropriate health and safety practices and to determine the applicability of any regulatory limitations prior to use. 1 Scope This part of ISO 1183 specifies a method for the determination of the density or the specific volume of solid non- cellular plastics of any shape which do not contain c
15、losed pores. 2 Terms, definitions, symbols, units and abbreviated terms For the purposes of this part of ISO 1183, the following terms, definitions, symbols, units and abbreviated terms apply: 2.1 test material material to be tested 2.2 test specimen that part of the test material actually subjected
16、 to the test 2.3 mass m quantity of matter contained in a body NOTE Mass is expressed in kilograms (kg) or grams (g). 2.4 weight W force produced by gravity acting on a mass NOTE 1Since gravity varies with location, so does weight. NOTE 2Weight is expressed in newtons (N). ISO 1183-3:1999(E) ISO 2 2
17、.5 apparent mass mapp mass of a body obtained by measuring its weight using an appropriately calibrated balance NOTE Apparent mass is expressed in kilograms (kg) or grams (g). 2.6 volume V size of a body in three-dimensional space, excluding pores NOTE 1Due to thermal expansion, volume varies with t
18、emperature T. NOTE 2Volume is expressed in cubic metres (m3), litres (l), cubic centimetres (cm3) or millilitres (ml). 2.7 density r mass per unit volume of a material at a given temperature T NOTE 1Density is calculated using the equation rT m V = app at constant T(1) NOTE 2It is expressed in kilog
19、rams per cubic metre (kg/m3), kilograms per cubic decimetre (kg/dm3), grams per cubic centimetre (g/cm3), kilograms per litre (kg/l) or grams per millilitre (g/ml). 2.8 specific volume v volume per unit mass of a material at a given temperature T NOTE 1Specific volume is calculated using the equatio
20、n v V T T T = mapp 1 r at constant T(2) NOTE 2It is expressed in cubic metres per kilogram (m3/kg), cubic decimetres per kilogram (dm3/kg), cubic centimetres per gram (cm3/g), litres per kilogram (l/kg) or millilitres per gram (ml/g). NOTE 3Density is to be distinguished from specific gravity, which
21、 is the ratio of the weight of a given volume of a material to that of an equal volume of water at a stated temperature T. 3 Principle 3.1 The volume of a specimen of known apparent mass is determined by measuring the change of gas volume within a pyknometer upon introducing the specimen. The volume
22、 change may be obtained either directly by means of a movable piston or indirectly by measuring the change of the pressure within the pyknometer and calculating the volume using the pressure-volume relationship for ideal gases. The volume obtained by this procedure is related to the solid alone with
23、out its pores. Density is calculated using eq. (1) given above. 3.2 The smaller the molecules of the gas the narrower the pores will be that can be penetrated. 3.3 Preferably gases of low affinity of adsorption onto the test material should be used. ISOISO 1183-3:1999(E) 3 3.4 Particularly for press
24、ure-measuring pyknometers the accuracy of the method depends on the applicability of the ideal gas law (Boyle - Mariotte law). NOTE For high-accuracy measurements, helium should preferably be used because it behaves most like an ideal gas. It can penetrate into pores at least as small as 1 m diamete
25、r and has a low tendency to adsorb onto the surface of the test material. 4 Apparatus and materials 4.1 Analytical balance, accurate to 0,1 mg. 4.2 Gas pyknometer, of suitable cell volume, accurate to 0,01 % of the cell volume. NOTE Accuracy is improved if the test specimen fills as much of the cell
26、 as possible. An example of a two-chamber pressure-type pyknometer is given in annex A, together with a procedure for its calibration and operation. 4.3 Measurement gas, preferably helium with a purity of 99,99 % or better for highest accuracy, or other non- corrosive and non-adsorbing gas, e.g dry
27、air, at a pressure of up to 300 kPa. 4.4 Thermostatically controlled bath or enclosure, capable of maintaining the desired test temperature T (preferably 23 C) to the nearest 1 C. Alternatively, a gas pyknometer with a suitable built-in temperature control may be used. 5 Test specimens 5.1 If not ex
28、cluded by the conditioning procedure, dry test specimens to constant mass before carrying out any volume measurements. Take care to choose suitable drying conditions to prevent changes in density of the test material. 5.2 Test materials consisting of powder, granules, pellets or flakes can be tested
29、 as received. Other materials may be cut to any shape convenient for the size of the pyknometer cell used. Take care to avoid changes in density resulting from compressive stresses on the material during cutting. Prepare specimens containing closed pores in a suitable way, e.g. by grinding. 5.3 Spec
30、imens whose change in density on conditioning may be greater than the accuracy required of the density determination shall be conditioned before testing in accordance with the relevant material standard. Conditioning at a particular humidity or to a constant degree of crystallinity may be required.
31、5.4 When changes in density as a function of time or the ambient conditions are the main purpose of the determination, condition the specimens as agreed by the interested parties. 6 Calibration Set the pyknometer to the desired temperature T, preferably 23 C. Adjust the volumes of the pyknometer cel
32、ls to the desired values or measure the volumes of the empty cells. Determine the mass of a calibration specimen of known density to the nearest 0,1 mg or use a calibration specimen of known volume. Introduce the calibration specimen into the measurement cell. Purge for 3 min with the measurement ga
33、s to replace the air and any humidity which may be adsorbed on the surface of the specimen. If necessary, allow additional time for temperature equilibrium to be established. When the preset temperature has been reached, measure the change in volume or pressure produced by introduction of the specim
34、en in accordance with the principles of operation of the particular type of pyknometer used. Determine the calibration factor kc from equation (3a) or (3b). NOTE When using a pressure-type apparatus, the volume of the specimen can be calculated from the pressure change using the pressure-volume rela
35、tionship for ideal gases (Boyle-Mariotte law). This may be done automatically by some pyknometers. ISO 1183-3:1999(E) ISO 4 k V V c c c o =(3a) k V m c cc c o = r (3b) where Vcis the measured volume of the calibration specimen; Vcois the known volume of the calibration specimen; cois the known densi
36、ty of the calibration specimen; mcis the mass of the calibration specimen. Recalibrate the pyknometer if the cell volume or temperature is changed, a different measurement gas is used or the pressure of the measurement gas is changed significantly. 7 Procedure and calculation Repeat the procedure de
37、scribed in the clause 6 using the test specimen. Calculate the density using the equation rs s s T m V T = kc(4) where msis the mass of the test specimen; VsTis the volume of the test specimen at temperature T. Carry out the determination on three or more test specimens of the same material. 8 Preci
38、sion The precision of this test method is not known because inter-laboratory data are not available. When such data become available, a precision statement will be added at the following revision. NOTE The reproducibility can be expected to be better than approximately 0,2 %, while the repeatability
39、 can be expected to be better than approximately 0,1 %. 9 Test report The test report shall include the following details: a) a reference to this part of ISO 1183; b) all details necessary for the complete identification of the material tested; c) the arithmetic mean density for all the specimens te
40、sted, and the standard deviation of the mean; d) the number of specimens tested and the mass of each; ISOISO 1183-3:1999(E) 5 e) details of any conditioning procedure used; f) the measurement gas used and its purity; g) the test temperature; h) the calibration material used; i) the type of pyknomete
41、r used and its manufacturer; j) details of any operation not specified in this part of ISO 1183 as well as details of any incident likely to have affected the results; k) the date of the test. ISO 1183-3:1999(E) ISO 6 Annex A (informative) Two-chamber pressure-type pyknometer A.1 Apparatus The appar
42、atus is composed of two inter-connected cells a measurement cell (volume Vmeas) and an expansion cell (volume Vexp), valves for the gas inlet (V1) and outlet (V3) and a valve (V2) separating the two cells, as shown in Figure A.1 a). The measurement cell is fitted with a pressure sensor. The pyknomet
43、er may be operated manually or automatically. A.2 Calibration Before starting the calibration procedure, the apparatus is purged by opening all the valves and sweeping both cells with gas, leaving the two cells full of gas at atmospheric pressure. The readout of the pressure sensor is then set to ze
44、ro. These preliminary operations are carried out before each calibration step. In the first calibration step see Figure A.1 a), valves V2 and V3 are closed. By opening valve V1, gas is allowed to flow into the measurement cell until the desired pressure p1o is reached. Then valve V1 is closed, valve
45、 V2 opened and the resulting equilibrium pressure p2o measured. In the second calibration step see Figure A.1 b), the same procedure is carried out with a calibration specimen of known volume Vc in the measurement cell. The measurement cell is again filled with gas until the desired pressure p1* is
46、reached and, after expansion, the resulting pressure p2* is measured. The volume of the measurement cell and that of the expansion cell can be calculated using equations (A.1) and (A.2), respectively. V Vpp pp p p pp meas c * * * o oo () ()() = 12 12 2 2 12 2 222 (A.1) VV pp p expmeas oo o = 12 2 (A
47、.2) where p1o, p2oare the pressures in the empty pyknometer respectively before and after expansion into the expansion cell; p1*, p2*are the pressures in the pyknometer containing the calibration specimen respectively before and after expansion into the expansion cell; Vcis the volume of the calibra
48、tion specimen; Vmeasis the volume of the measurement cell; Vexpis the volume of the expansion cell. ISOISO 1183-3:1999(E) 7 A.3 Procedure After introducing the specimen into the measurement cell, the specimen volume is measured in the same way as in one of the calibration steps see Figure A.1 c). Ha
49、ving brought the measurement cell to pressure p1, the equilibrium pressure p2 is obtained by allowing the gas to expand into the expansion cell. The volume of the test specimen at temperature T is given by equation (A.3): smeas exp T V V V p p =2 2 1 2 1 (A.3) where p1, p2are the pressures in the pyknometer containing the test specimen respectively before and after expansion into the expansion cell; VsTis the volume of the test specimen at temperature T. The density can be calculated by dividing the mas