SIST EN ISO 182-4:2001

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kunststoffe - Bestimmung der Neigung von Formmassen und Erzeugnissen auf der Basis von Vinyl-chlorid-Homopolymeren und -Copolymeren, bei erhöhten Temperaturen Chlorwasserstoffund andere saure Produkte abzugeben - Teil 4: Potentiometrisches Verfahren (ISO 182-4:1993)Plastiques - Détermination de la tendance des compositions a base d'homopolymeres et copolymeres du chlorure de vinyle a dégager du chlorure d'hydrogene et éventuellement d'autres produits acides a températures élevées - Partie 4: Méthode potentiométrique (ISO 182-4:1993)Plastics - Determination of the tendency of compounds and products based on vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures - Part 4: Potentiometric method (ISO 182-4:1993)83.080.20PlastomeriThermoplastic materialsICS:Ta slovenski standard je istoveten z:EN ISO 182-4:2000SIST EN ISO 182-4:2001en01-junij-2001SIST EN ISO 182-4:2001SLOVENSKI
STANDARD



SIST EN ISO 182-4:2001



SIST EN ISO 182-4:2001



SIST EN ISO 182-4:2001



SIST EN ISO 182-4:2001



INTERNATIONAL STANDARD ISO 182-4 First edition 1993-04-01 Plastics - Determination of the tendency of compounds and products based on Vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures - Part 4: Potentiometric method Plas tiques - 06termination de Ia tendance des compositions 2 base d’homopolym&res et copolym&es du chlorure de vinyle 3 degager du chlorure d’h ydrogene et 6ven tuellemen t d’autres produits acides 2 temp&a tures elevees - Partie 4: M6 thode po ten tiom6 trique Reference number ISO 182-4:1993(E) SIST EN ISO 182-4:2001



ISO 182=4:1993(E) 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. Esch 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. 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. International Standard ISO 182-4 was prepared by Technical Committee ISO/TC 61, Plastics, Sub-Committee SC 6, Ageing, Chemical and environ- mental resis tance. Together with the three other Parts of ISO 182, it cancels and replaces ISO Recommendation R l82:1970, of which the four Parts of ISO 182 consti- tute a technical revision. ISO 182 consists of the following Parts, under the general title Plas tics - Determination of the tendency of compounds and products based on Vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated tempera tures: - Part 1: Congo red method - Part 2: pH method - Part 3: Conductometric method - Part 4: Potentiometric method Annexes A and B of this part of ISO 182 are for information only. 0 ISO 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronie or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-l 211 Geneve 20 l Switzerland Printed in Switzerland SIST EN ISO 182-4:2001



INTERNATIONAL STANDARD ISO 182=4:1993(E) Plastics - Determination of the tendency of compounds and products based on Vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures - Part 4: Potentiometric method WARNING - The use of this part of ISO 182 may involve hazardous materials, operations and equipment. This part of ISO 182 does not purport to address all of the safety Problems associated with its use. lt is the responsibility of the user of this part of ISO 182 to establish appropriate safety and health practices and determine the applicability of regulatory limitations Prior to use. 1 Scope 1.1 This part of ISO 182 specifies a method for the determination of the thermal stability at elevated temperature of compounds and products based on Vinyl chloride homopolymers and copolymers (in the following text abbreviated as PVC) which undergo dehydrochlorination (the evolution of hydrogen chlor- ide). 1.2 The method may be used as a quality control test during manufacture and conversion of PVC com- pounds. lt may also be used for the characterization of PVC compounds and products, especially with re- gard to the effectiveness of their heat-stabilizing sys- tems. lt is suitable for coloured PVC compounds and prod- ucts for which a discolouration test under the action of heat may be unsatisfactory. 1.3 The method is recommended for compounded PVC materials and products only, although it tan be used for polymers in powder form under appropriate conditions to be agreed upon between the interested Parties. The method is not recommended for PVC compounds in the form of dry blends, since such materials may not be sufficiently homogeneous. 1.4 PVC compounds and products may evolve other decomposition products in addition to hydrogen chloride at elevated temperatures. A limited number of these products, originating from the decomposition of certain comonomers (such as Vinyl esters of or- ganic acids) or of plasticizers, stabilizers and other additives, may effect the pH or the conductivity of an aqueous Solution when they are absorbed. Conse- quently, the results obtained for different products by the methods described in Parts 2 and 3 of ISO 182 may not be comparable with those obtained using the method described in the present part of ISO 182. 1.5 This part of ISO 182 specifies a potentiometric method for the determination of chloride ion (Cl-) concentration (expressed as pCI) in an absorbing sol- ution, independent of the presence of other ions. The value pCl is defined as - Ig ccI, where ccI is the molar concentration of chloride ions. This method is, there- fore, particularly recommended for plasticized PVC compounds and copolymers. 1 SIST EN ISO 182-4:2001



ISO 182=4:1993(E) 1.6 This method may also be applied to other plas- tics materials that tan evolve hydrogen chloride when heated under the conditions prescribed by the rel- evant specifications, or as agreed upon between the interested Parties. 2 Normative references The following Standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 182. At the time of publication, the editions indicated were valid. All Standards are subject to revision, and Parties to agreements based on this part of ISO 182 are encouraged to investigate the possibility of applying the most recent editions of the Standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 182-2:1990, Plastics - Determination of the tendency of compounds and products based on Vinyl chloride homopolymers and copolymers to evolve hy- drogen chloride and an y other acidic products at el- evated temperatures - Part 2: pH method. ISO 182-3:1993, Plastics - Determination of the tendency of compounds and products based on Vinyl chloride homopolymers and copolymers to evolve hy- drogen chloride and any other acidic products at el- evated temperatures - Part 3: Conductometric method. ISO 565:1990, Test sieves - Metal wire cloth, per- forated metal plate and electroformed sheet - Nom- inal sizes of openings. 4 Principle A test Portion of the PVC compound or product is maintained at an agreed temperature in a nitrogen gas stream and the hydrogen chloride evolved is absorbed in a given amount of an appropriate Solution. The amount of hydrogen chloride evolved is determined potentiometrically in relation to the recorded Change in pCI of the absorbing Solution. 5 Reagents During the test, use only reagents of recognized ana- lytical grade in accordance with ISO 6353-2. 5.1 Pure nitrogen, containing less than 6 ppm oxy- gen and less than 0,l ppm carbon dioxide by volume. The purity shall be such that when the gas is passed through the absorbing Solution for 1 h at a rate of 7,2 I/h + 0,l I/h, the conductivity of the water re- mains Ükhanged. The gas shall be dried by passing it through a suitable drying agent and the flow-rate through the dehydro- chlorination cell adjusted by means of a needle valve and measured using a suitable flowmeter. 5.2 Hydrochlorit acid, aqueous Solution, c(HCI) = 0,Ol mol/l. 5.3 Distilled or demineralized water. ISO 4793: 1980, Laboratory sintered (fritted) filters - Porosity grading, classifica tion and designa tion. ISO 5725:1986, Precision of test methods - Deter- mination of repeatability and reproducibility for a Standard test method by inter-laboratory tests. 5.4 Potassium nitrate (KNO,), potassium sulfate (K,SO,) or other salts, for the preparation of the ab- sorbing Solution (see 10.4). ISO 6353-2:1983, Reagents for Chemical analysis - Part 2: Specifications - First series. 6 Apparatus 3 Definition The general arrangement of the apparatus, shown in figure 1, includes a re-usable dehydrochlorination cell A. This cell may be replaced by a disposable cell B. For the purposes of this patt of ISO 182, the following definition applies. 6.1 Dehydrochlorination cells. 3.1 stability time, ts: Time, measured by reference to a predetermined Change in the pCI of an absorbing Solution, required for a certain amount of hydrogen chloride to be evolved when a prescribed mass of PVC compound or product is maintained at an elev- ated temperature under the test conditions specified in this part of ISO 182. 6.1.1 Gell A (re-usable), with shape and dimensions as shown in figure2. A recommended procedure for cleaning the cell is given in annex A. 2 SIST EN ISO 182-4:2001



ISO 182=4:1993(E) 6.1.2 Cell B (disposable), with shape and dimen- sions as shown in figure3. 6.2 Test Portion holder, for use with cell A. The test portion is supported on a porous sintered-glass disc (grade P 100, see ISO 4793), 10 mm in diameter. NOTE 1 Other types of cell may be employed if it has been proved that the results obtained are equivalent to those obtained with one of the cells described in 6.1 .l and 6.1.2. To prevent blocking of the porous disc, it is advisable to place a thin, soft layer of glass wool between it and the test Portion. i 1 T 5 6 4 1 Nzcylinder 2 Purification train 3 Ball flowmeter 4 Electronictemperature Controller (scale division 0,l'C) 5 Temperature Sensor 6 Heatingbath 7 PVCtestportion 8 Dehydrochlorination ceLL 9 Thermometer (scale division 0,l'C) 10 Silicone 0iL 11 Magnetit stirrer 12 Absorbing Solution 13 Measuring electrodek) 14 Potentiometer 15 Recorder Figure 1 - General arrangement of apparatus SIST EN ISO 182-4:2001



SIST EN ISO 182-4:2001



ISO 182=4:1993(E) Dimensions in millimetres U-tube (Wall thickness 1) @ int. 6 m 190 - L Figure 3 - Cell B (disposable) for dehydrochlorination of PVC samples A recommended procedure for cleaning the disc sup- port is given in annex A. 6.3 Glass connection tube, for use with cell A, having dimensions as shown in figure4. The con- nection tube is secured to cell A by two springs fixed to hooks on the ground-glass joints. The tube shall be provided with an insulating jacket. 6.4 Expansion joints and cell connections, for use with cell B. Cell B is connected to the apparatus through flexible polytetrafluoroethylene (PTFE) and Silicone rubber tubes. Special joints allow for thermal expansion. The complete joint arrangement is shown in figure 5. 6.5 Oil bath, with a capacity of at least 10 1. The bath shall be capable of operating in the temperature range 170 “C to 210 “C and of maintaining the test temperature with an accuracy of 0,l “C. The bath shall be designed in such a way that the temperature distribution is even throughout, and shall have a thermal capacity sufficient to avoid tempera- ture Change when the dehydrochlorination cell is im- mersed in it. 6.6 Thermometer, with a scale suitable for reading the heating bath temperature in the range 170 “C to 210 “C and with a scale division of 0,l “C. 6.7 Balance, with a scale division of 1 mg. 6.8 Measurement cell A suitable measurement cell is shown in figure6. lf the diameters of the measurement electrode and the feed tube for the gases from decomposition of the test Portion are sufficiently small, a 400 ml Erlenmeyer flask is a suitable alternative measure- ment cell. A recommended procedure for cleaning the cell is given in annex A. 6.9 Magnetit stirrer, capable of providing gentle agitation within the measurement cell. 6.10 Potentiometer, for the determination of the PC1 . 6.10.1 Specific electrode for the Cl- ions, having a precision of at least 0,Ol pCI. The sensitive element is a silver chloride (AgCI) crystal (see annex B). 6.10.2 Reference electrode on the basis of calomel (mercurous chloride) (Hg/Hg,Cl,/saturated KCI) or of mercurous sulfate (Hg/Hg,SO,/saturated K2SOJ or other, according to the specifications of the supplier of the specific electrode. 6.10.3 Extension (salt bridge), for the reference electrode. For the measurement of Cl- ions, a salt bridge is absolutely necessary if a mercurous chloride electrode is used. NOTE 2 Some “combined” specific electrodes are com- mercially available which also include a reference electrode (see annex B). 6.10.4 Electronie millivoltmeter. The apparatus shall be provided with a device for automatic temperature compensation and equipped with an output for a recording device. 6.11 Stopclock, or other suitable timing device, i
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