ISO-1628-3-2001.pdf

Reference number ISO 1628-3:2001(E) ©ISO 2001 INTERNATIONAL STANDARD ISO 1628-3 Second edition 2001-06-01 Plastics Determination of the viscosity of polymers in dilute solution using capillary viscometers Part 3: Polyethylenes and polypropylenes Plastiques Détermination de la viscosité des polymères en solution diluée à l'aide de viscosimètres à capillaires Partie 3: Polyéthylènes et polypropylènes Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ©ISO 2001 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 either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii© ISO 2001 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) © ISO 2001 All rights reservediii Foreword ISO (the International 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 established 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 standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International 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. Attention is drawn to the possibility that some of the elements of this part of ISO 1628 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 1628-3 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9, Thermoplastic materials. This second edition cancels and replaces the first edition (ISO 1628-3:1991), of which it constitutes a minor revision (the second equation in 8.1 has been corrected and the terminology has been aligned with that used in ISO 1628-1). ISO 1628 consists of the following parts, under the general title Plastics Determination of the viscosity of polymers in dilute solution using capillary viscometers: Part 1: General principles Part 2: Poly(vinyl chloride) resins Part 3: Polyethylenes and polypropylenes Part 4: Polycarbonate (PC) moulding and extrusion materials Part 5: Thermoplastic polyester (TP) homopolymers and copolymers Part 6: Methyl methacrylate polymers Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARDISO 1628-3:2001(E) © ISO 2001 All rights reserved1 Plastics Determination of the viscosity of polymers in dilute solution using capillary viscometers Part 3: Polyethylenes and polypropylenes 1Scope This part of ISO 1628 defines particular conditions for determining the reduced viscosity (also known as viscosity number) and intrinsic viscosity of polyethylenes and polypropylenes at 135 °C in dilute solution. It is applicable to low, medium and high-density polyethylenes and to a wide range of polypropylenes, including pure isotactic, stereoblock and atactic polymers. The viscosity of polymer solutions may be affected by additives present in the sample. The value of a reduced viscosity determined by this method may therefore be unreliable if the sample contains fillers or other additives. NOTEReduced viscosity is also known as the Staudinger function (Jv) and intrinsic viscosity as the Staudinger index (Jg). 2Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 1628. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 1628 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1628-1:1998, Plastics Determination of the viscosity of polymers in dilute solution using capillary viscometers Part 1: General principles ISO 3105:1994, Glass capillary kinematic viscometers Specifications and operating instructions 3Principle The times of flow of a solvent and a solution of polymer at a specified concentration in that solvent are measured at 135 °C. The reduced viscosity and intrinsic viscosity are calculated from these measurements and from the known concentration of the solution. Ethylene and isotactic polypropylene polymers are not soluble at room temperature in any known solvents. Precautions must therefore be taken during the test to avoid any precipitation of polymer, which would give an incorrect solution concentration. 4Solvent 4.1Decahydronaphthalene, analytical reagent grade, redistilled at a temperature not higher than 65 °C and a pressure of approximately 500 Pa; its peroxidation is prevented by suitable means, for example distilling in the presence of hydroquinone. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) 2© ISO 2001 All rights reserved Immediately after redistillation, 0,2 % by mass of antioxidant shall be added to inhibit oxidation during the viscosity determination. Antioxidants which have been found satisfactory include: ?4,4?-thio-bis-(6-tert-butyl-3-methyl)phenol; ?bis-(2-hydroxy-3-tert-butyl-5-methyl)phenylmethane; ?octadecyl-3-(3?,5?di-tert-butyl-4?-hydroxyphenyl) n-propionate; ?and tetrakismethylene 3-(3?,5?di-tert-butyl-4?-hydroxyphenyl) n-propionatemethane. Solvent stabilized in this way gives polymer solutions that are resistant to oxidation at 135 °C for several hours. 5Apparatus 5.1Ubbelohde viscometer, of which the essential dimensions are shown in Figure 1, or another type of viscometer listed in ISO 3105, provided it gives equivalent results to an Ubbelohde viscometer. However, in cases of dispute, an Ubbelohde viscometer shall be used. The preferred Ubbelohde viscometer design is shown in Figure 1, but other Ubbelohde viscometers can be used, provided that their capillary diameter and length and upper-bulb volume are the same as those indicated in Figure 1. If a viscometer of a type different from that shown in Figure 1 is used, the polymer solution is prepared in a 100 ml flask and the solution is filtered into the viscometer through a dry P 100 sintered-glass funnel. Before the filtration, the funnel is maintained at 150 °C in the oven (5.8). 5.2Viscometer holder, to hold the viscometer firmly in the correct position in the thermostatic bath. 5.3Thermostatic bath, maintained at 135 °C?0,2 °C, in accordance with ISO 1628-1. 5.4Thermostatic bath, maintained at 20 °C?0,1 °C. 5.5Temperature-measuring device, in accordance with ISO 1628-1 (scale division 0,1 °C). 5.6Timer, of any kind provided that it can be read to the nearest 0,1 s or better, and that it operates at a rate which is constant to?0,1 % over 15 min. 5.7Analytical balance, to weigh to an accuracy of 0,1 mg. 5.8Drying oven, maintained at 150 °C?2 °C. 5.9Glass-stoppered flask, 100 ml. 5.10Graduated pipette, 50 ml. 6Test sample 6.1The test sample shall be in the form of dry powder or very small pieces to facilitate dissolution. 6.2If the sample is a manufactured article, cut it into very small pieces (for example by cutting and grinding in the presence of solid carbon dioxide). Since the reduced viscosity of material from the sample surface could differ from that from the interior, one can ?either measure the reduced viscosity for the whole article by grinding it, homogenizing the ground material, dissolving a portion and taking a test sample from the solution; ?or measure the reduced viscosities for the surface and the interior separately by cutting small pieces from the surface and from the interior, grinding and homogenizing them separately and testing a sample taken from each. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) © ISO 2001 All rights reserved3 Dimensions in millimetres Key 1Volume 2 ml to 3 ml 2Capillary tube, ? 0,46 mm ? 0,02 mm 3Coil spring 4P 100 sintered-glass disc 5Ground-glass joint Figure 1 Ubbelohde viscometer modified for high-temperature tests Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) 4© ISO 2001 All rights reserved 7Procedure 7.1Cleaning the viscometer 7.1.1Before its utilization, or when inconsistent results are obtained, and in any case at regular intervals, clean the viscometer as specified in annex A of ISO 1628-1:1998. 7.1.2Between two successive determinations, clean the viscometer with the solvent being used for the determinations. During the cleaning procedure, maintain the viscometer, as well as the solvent, at 135 °C in thermostatic bath 5.3. After cleaning, remove the viscometer from the bath, cool to room temperature, wash with previously distilled and filtered acetone and dry in a dust-free air stream or under vacuum. 7.2Measurement of efflux time of solvent Determine the efflux time of the solvent by the procedure given in 7.5 for the solution. Use the average value of three consecutive readings agreeing to within 0,2 s in the calculation of the viscosity number. 7.3Choice of polymer solution concentration The polymer concentration shall be such that the ratio between the solution efflux time t and the solvent efflux time t0lies between 1,2 and 2. 7.3.1If the approximate value of the reduced viscosity of the polymer is known, choose the concentration from Table 1. Table 1 Concentration c to be used as a function of the reduced viscosity to be measured Reduced viscosityConcentration, c ml/gg/ml 40 to?2000,005 200 to 10000,001 ?1000 to 50000,0002 7.3.2If the approximate value of the reduced viscosity of the polymer is not known, test a solution of concentration 0,001 g/ml. If the reduced viscosity so obtained is not in the range prescribed in Table 1 for that concentration, repeat the test with the concentration in Table 1 corresponding to the value of the viscosity obtained. 7.4Preparation of the solution 7.4.1Calculate, to the nearest 1 mg, the mass m, in grams, of sample to be dissolved, using the equation: mcV? where cis the concentration, in grams per millilitre, of the solution at 135 °C; Vis the volume, in millilitres, of solvent used, measured at 20 °C (usually the solution is prepared using 50 ml of solvent); Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 08:42:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1628-3:2001(E) © ISO 2001 All rights reserved5 ?is the coefficient of expansion of the solvent between 20 °C and 135 °C, and is equal to the ratio of the densities at these temperatures, i.e. 20 135 0,888 1,107 0,802 ? ? ? ? Experimental evidence has shown that this value is constant even if the density at 20 °C (?20) is not exactly 0,888 g/ml. 7.4.2Weigh the calculated amount of the sample, with an accuracy of 0,2 mg, into the viscometer vessel (for examplemwill equal 0,0553 g for a concentration of 0,001 g/ml). Add the volumeVof solvent, transferring it with a graduated pipette (5.10) from a glass-stoppered flask (5.9) maintained at 20 °C?0,1 °C in thermostatic bath 5.4. Close the viscometer vessel see Figure 1b) and place it and the viscometer in the oven (5.8) at 150 °C. Keep the vessel in the oven until visual examination shows no undissolved particles, gels or particles of foreign matter, removing the vessel from the oven and examining the solution every 10 min, and stirring the solution carefully so that the polymer par