1、DEUTSCHE NORM October 1998 Plastics - Determination of time-temperature limits after prolonged exposure to heat (IS0 2578 : 1993) English version of DIN EN IS0 2578 DIN EN IS0 2578 - ICs 83.080.01 Descriptors: Plastics, thermal resistance, testing. Supersedes DIN IS0 2578, August 1994 edition. Kunst
2、stoffe - Bestimmung der Temperatur-Zeit-Grenzen bei lang- anhaltender Wrmeeinwirkung (IS0 2578 : 1993) European Standard EN IS0 2578 : 1998 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken
3、by CEN/TC 249 to adopt, without alteration, International Standard IS0 2578 as a European Standard. The responsible German body involved in its preparation was the Normenausschu Kunststoffe (Plastics Standards Committee), Technical Committee Verhalten gegen Umgebungseinflsse. DIN EN IS0 291 is the s
4、tandard corresponding to International Standard IS0 291 referred to in clause 2 of the EN. Amendments IS0 2578 having been adopted as a European Standard, the status of the corresponding DIN Standard (DIN EN IS0 2578) has been changed accordingly. Previous editions DIN 53446: 1962-1 O; DIN IS0 2578:
5、 1994-08. National Annex NA Standard referred to (and not included in Normative references and Annex ZA) DIN EN IS0 291 Plastics - Standard atmospheres for conditioning and testing (IS0 291 : 1997) EN comprises 17 pages. No pari of this standard may be reproduced without the prior permission of Ref.
6、 No. DIN EN IS0 2578 : 1998-1 Y Deutsches Institut fr Normung e. V., Berlin. wth Verlag GmbH, D-10772 Berlin, has the exclusive right of sale for German Standards (DIN-Normen). English price group 10 Sales No. 11 10 04.99 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 2578 August 1998 ICs
7、83.080.01 Descriptors: Plastics, thermal resistance, testing. English version Plastics Determination of time-temperature limits after prolonged exposure to heat (IS0 2578 : 1993) Plastiques - Dtermination des limites temps-tempratures aprs exposition laction prolonge de la chaleur (IS0 2578 : 1993)
8、Kunststoffe - Bestimmung der Tempe- ratur-Zeit-Grenzen bei langanhalten- der Wrmeeinwirkung (IS0 2578 : 1993) This European Standard was approved by CEN on 1998-06-1 2. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European St
9、andard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stand- ards may be obtained on application to the Central Secretariat or to any CEN member. The European Standards exist in three official versions (English, Fren
10、ch, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, the Czech Republic,
11、 Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de
12、 Stassart 36, B-1050 Brussels O 1998. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN IS0 2578 : 1998 E Page 2 EN IS0 2578 : 1998 Foreword International Standard IS0 2578 : 1993 which was prepared by ISO/TC 61 Plastics of the Int
13、ernational Organization for Standardization, has been adopted by Technical Committee CEN/TC 249 Plastics, the Secretariat of which is held by IBN, as a European Standard. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorse
14、ment, and conflicting national standards withdrawn, by February 1999 at the latest. In accordance with the CENKENELEC Internal Regulations, the national standards organizations of the follow- ing countries are bound to implement this European Standard: Austria, Belgium, the Czech Republic, Denmark,
15、Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. Plastics - Determination of time-temperature limits after prolonged exposure to heat, Endorsement notice The text of the International Standar
16、d IS0 2578 : 1993 was approved by CEN as a European Standard without any modification. NOTE: Normative references to international publications are listed in Annex ZA (normative) Contents 1 2 3 4 5 6 7 8 9 10 11 12 13 Page Scope . 3 Normative references . 3 Definitions 4 Principle . 4 Choice of test
17、 5 Choice of end-point . 5 Test specimens Exposure temperatures Ageing ovens 5 Procedure 5 Evaluation of results . . 6 Determination of the relative temperature index . 9 Test report . 1 O Annexes A Calculation of the regression line 11 B Correlation coefficient 15 C Recommended test schedule for pr
18、imary properties 16 Page 3 EN IS0 2578 : 1998 Introduction During the preparation of this International Standard, account was taken of the contents of IEC 216. Accordingly, the terms and definitions in this International Standard, as well as the procedures described, are in line or identical with th
19、ose specified in IEC 216. 1 Scope 1.1 This International Standard specifies the princi- ples and procedures for evaluating the thermal en- durance properties of plastics exposed to elevated temperature for long periods. 1.2 The term thermal endurance is used here to re- fer to tests made in air, exc
20、luding any other influence or stress applied to the test specimens. Thermal en- durance properties evaluated in different environ- ments and/or with different stresses applied to the test specimens require different test procedures. 1.3 In this International Standard, the study of the thermal ageing
21、 of plastics is based solely on the change in certain properties resulting from a period of exposure to elevated temperature. The properties studied are always measured after the temperature has returned to ambient. The various properties of plastics change at various rates on thermal ageing. To ena
22、ble comparisons to be made of the thermal ageing of different plastics, the criteria for judgement depend on the type of property to be studied and its acceptable limiting value. 1.4 In the application of this standard it is assumed that a practically linear relationship exists between the logarithm
23、 of the time required to cause the predeter- mined property change and the reciprocal of the cor- responding absolute temperature (Arrhenius Law). For the plastics tested, no transition, in particular a first-order transition, should occur in the temperature range under study. 2 Normative references
24、 The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- 1) To be published. 15B (B.C.) 821 cation, the editions indicated were valid. All standards are subject to revision, and parties to agreement
25、s based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 291 :I 977, Plastics - Standard atmospheres for co
26、nditioning and testing. IEC 216-1:1990, Guide for the determination of ther- mal endurance properties of electrical insulating ma- terials - Part l: General guidelines for ageing procedures and evaluation of test results. I EC 21 6-2: 1990, Guide for the determination of ther- mal endurance properti
27、es of electrical insulating ma- terials - Part 2: Choice of the test criteria. I EC 2 16-3-1 : 1990, Guide for the determination of thermal endurance properties of electrical insulating materials - Part 3: Instructions for calculating thermal endurance characteristics - Section 1: Calculations using
28、 mean values of normally distributed complete da ta. IEC 216-3-3:-,) Guide for the determination of ther- mal endurance properties of electrical insulating ma- terials - Part 3: Instructions for calculating thermal endurance characteristics - Section 3: Calculations for incomplete data. IEC 216-4-1:
29、199, Guide for the determination of thermal endurance properties of electrical insulating materials - Part 4: Ageing ovens - Section 1: Single-chamber ovens. IEC 216-5:1990, Guide for the determination of ther- mal endurance properties of electrical insulating ma- terials - Part 5: Guidelines for th
30、e application of thermal endurance characteristics. Page 4 EN IS0 2578 : 1998 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 temperature index (TI): Number corresponding to the temperature, in degrees Celsius, derived from the thermal endurance re
31、lationship at a given time (normally 20 O00 h). 3.2 relative temperature index (RTI): Temperature index of a test material, obtained at the time which corresponds to the known temperature index of a reference material when both materials are subjected to the same ageing and diagnostic procedures in
32、a comparative test. 3.3 ha Iving interval (HIC) : Num ber correspond i ng to the temperature interval, in degrees Celsius, which expresses the halving of the time to end-point taken at the temperature of the TI or the RTI. HIC is a measure of the slope of the thermal endur- ance graph. It is not con
33、stant, but varies with tem- perature even when the thermal endurance relationship is linear. In many practical cases, the error arising from the use of HIC in the temperature range of interest remains within acceptable limits. 3.4 thermal endurance graph (Arrhenius graph): Graph in which the logarit
34、hm of time to reach a specified end-point in a thermal endurance test is plotted versus the reciprocal thermodynamic (abso- lute) test temperature. 3.5 threshold value: Value, corresponding to a per- centage of the initial value of the property under in- vestigation. at which the ageing test is stop
35、ped and the time to failure is calculated. NOTES 1 The level of 50 % is often used to determine the threshold value. 2 If a minimum value is required after ageing, it may be agreed between the interested parties to use this minimum value as the threshold value, instead of a percentage of the initial
36、 value. 3.6 test-specimen failure time: Time required at the exposure temperature for a specimen to either fail the proof test or reach the threshold value of the characteristic under investigation, whichever is shorter. 4 Principle 4.1 Determination of time to failure At a chosen temperature, the v
37、ariations in the nu- merical value of a chosen characteristic (for example, a mechanical, optical or electrical property) are deter- mined as a function of time. The procedure is continued until the relevant thresh- old value of that characteristic has been reached, re- sulting in the time to failur
38、e at that particular temperature. Further specimens are exposed at at least two other temperatures and the variations in the relevant char- acteristic determined. It is recommended to heat-age test specimens at three to four temperatures, and determine the time to failure for each of the tem- peratu
39、res. 4.2 Determination of TI The times to failure are plotted versus the reciprocal values of the exposure temperatures. The intersection of this curve with the chosen time limit (in general 20 O00 h) gives the temperature index sought. 4.3 Use of correlation coefficient The reliability of the extra
40、polation of.the graph de- pends on obtaining an acceptable Arrhenius plot, which may not be possible with materials showing behaviour related to a transition phenomenon in the chosen temperature range. For this purpose the correlation coefficient r is calcu- lated in accordance with annex B. If this
41、 calculation results in a value smaller than 0,95 (for three test temperatures; see also IEC 2161, an additional test at a different test temperature may improve the linearity of data. 4.4 Determination of RTI For determination of RTI, the chosen reference plas- tic, its thermal endurance and the me
42、thod of deter- mination are of central importance. The reference plastic shall be of the same type as the tested plastic, and have a history of satisfactory ser- vice. It shall have a known temperature index for the property and a threshold value which are the same, or at least reasonably similar to
43、, those to be employed in the RTI test. The TI and HIC of the reference ma- terial should also be approximately the same as the values expected for the tested plastic. Since processing conditions may significantly affect the ageing characteristics of some materials, the sampling, cutting of sheet fr
44、om the supply roll, cutting of anisotropic material in the same direction, mould- ing, curing, preconditioning, etc. shall be performed in the same manner for both materials, and the speci- mens shall be tested in the same thickness. Page 5 EN IS0 2578 : 1998 5 Choice of test The test chosen shall r
45、elate to a characteristic which is likely to be of significance in practice and, wherever possible, use shall be made of test methods specified in International Standards. If the dimensions and/or form of the test specimens are altered by the heat treatment, then only test methods which are inde- pe
46、ndent of these effects may be used. 6 Choice of end-point For the selection of the end-point, two factors shall be agreed upon: a) the period of time for which a time-temperature limit shall be estimated; for general purposes, a period of 20 O00 h is recommended; NOTE 3 Other times (shorter or longe
47、r than 20 O00 h) may be chosen if necessary b) the acceptable threshold value of the chosen characteristic; this threshold value depends on the conditions of use foreseen. 7 Test specimens 7.1 The dimensions and method of preparation of the test specimens shall be in accordance with the specificatio
48、ns given for the relevant test method. 7.2 For a criterion requiring a destructive test, the minimum total number (n) of test specimens needed depends on - the number a of test specimens required for one test, according to the test specifications given for the relevant test method; - the number b of
49、 tests necessary to determine the end-point at one exposure temperature; - the number c of exposure temperatures; - the number d of specimens needed for the initial Thus the total number of specimens is: test before heat ageing. n = abc+d For a criterion requiring non-destructive testing, and for each exposure temperature, in most cases a group of five test specimens is adequate. NOTES 4 When there is a large number of specimens to be tested, it may be possible in certain cases to deviate from the relevant test specifications and to reduce this number. However, it
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