1、BRITISH STANDARD BS EN ISO 2578:1999 BS 2782-1: Method 135:1993 Incorporating Amendment No. 1 (renumbers the BS as BS EN ISO 2578:1999) Plastics Determination of time-temperature limits after prolonged exposure to heat IMPORTANT NOTE. Before reading this method it is essential to read BS 2782-0, Int
2、roduction, issued separately. The European Standard ENISO2578:1998 has the status of a British Standard ICS 83.080.01BSENISO2578:1999 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, was published underthe authority of the Standard
3、s Board and comes into effect on 15December1993 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference PRM/21 Draft for comment 90/38737 DC ISBN 0 580 22743 X Committees responsible for this British Standard The preparation of this British Standard was entr
4、usted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/21, upon which the following bodies were represented: British Plastics Federation British Textile Confederation Department of the Environment (Building Research Establishment) Department of Trade and Indus
5、try (National Physical Laboratory) Electrical and Electronic Insulation Association (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Institute of Materials Ministry of Defence Packaging and Industrial Films Association Pira International RAPRA Technology Ltd. Amendments issued since publication Amd. No. Date Comme
6、nts 10349 May 1999 Indicated by a sideline in the marginBSENISO2578:1999 BSI 03-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Principle 4 5 Choice of test 5 6 Choice of end-point 5 7
7、Test specimens 5 8 Exposure temperature 5 9 Ageing ovens 5 10 Procedure 5 11 Evaluation of results 6 12 Determination of the relative temperature index 6 13 Test report 10 Annex A (normative) Calculation of the regression line 11 Annex B (normative) Correlation coefficient 16 Annex C (informative) R
8、ecommended test schedule for primary properties 16 Annex ZA (normative) Normative references to international publications with their relevant European publications 17 Figure 1 Determination of the time to reach the end-point at each temperature Property variation 7 Figure 2 Thermal endurance graph
9、Temperature index Halving interval 8 Figure 3 Thermal endurance graph Relative temperature index Halving interval 9 Figure A.1 Plot of regression line based on sample calculation 15 Table A.1 Commonly used test temperatures, in degrees Celsius, corresponding values in kelvins with their reciprocal a
10、nd reciprocal squared values 13 Table A.2 Sample calculation 14 List of references Inside back coverBSENISO2578:1999 ii BSI 03-2000 National foreword This British Standard is the English language version of ENISO2578:1998 The terms “temperature index” and “relative temperature index” used in this st
11、andard should not be confused with temperature indices used in flammability tests. WARNING NOTE. This British Standard, which is identical with ENISO2578, does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety at Work etc. Act1974. Attention shoul
12、d be paid to any appropriate safety precautions and the method should be operated only by trained personnel. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British
13、Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 291:1977 BS 2782: Methods of testing plastics Part 0:1992: Introduction (Annex A is identical) Summary of pages This document comprises a front cover, an ins
14、ide front cover, pages i and ii, theEN ISOtitle page, pages 2 to 18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EU
15、ROPENNE EUROPISCHE NORM EN ISO 2578 August 1998 ICS 83.080.10 Descriptors: See ISO document English version PlasticsDetermination of time-temperature limits after prolonged exposure to heat (ISO2578:1993) Plastiques Dtermination des limites temps-tempratures aprs exposition laction prolonge de la ch
16、aleur (ISO2578:1993) Kunstsoffe Bestimmung der Temperatur-Zeit-grenzen bei langanhaltender Wrmeeinwirkung (ISO2578:1993) This European Standard was approved by CEN on12June1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this E
17、uropean Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (Engl
18、ish, French, 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, CzechRepub
19、lic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stass
20、art 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref. No. EN ISO2578:1998EEN ISO2578:1998 2 BSI 03-2000 Foreword The text of the International Standard from Technical Committee ISO/TC61, Plastics, of the Internationa
21、l Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC249, Plastics, the secretariat of which is held by IBN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorseme
22、nt, at the latest by February1999, and conflicting national standards shall be withdrawn at the latest by February1999. According to CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czec
23、hRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Endorsement notice The text of the International Standard ISO2578:1993 has been approved by CEN as a European Standard without a
24、ny modification. NOTENormative references to International Standards are listed in Annex ZA (normative).EN ISO2578:1998 BSI 03-2000 3 Introduction During the preparation of this International Standard, account was taken of the contents of IEC216. Accordingly, the terms and definitions in this Intern
25、ational Standard, as well as the procedures described, are in line or identical with those specified in IEC216. 1 Scope 1.1 This International Standard specifies the principles and procedures for evaluating the thermal endurance properties of plastics exposed to elevated temperature for long periods
26、. 1.2 The term thermal endurance is used here to refer to tests made in air, excluding any other influence or stress applied to the test specimens. Thermal endurance properties evaluated in different environments and/or with different stresses applied to the test specimens require different test pro
27、cedures. 1.3 In this International Standard, the study of the thermal ageing 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 vari
28、ous properties of plastics change at various rates on thermal ageing. To enable 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
29、 assumed that a practically linear relationship exists between the logarithm of the time required to cause the predetermined property change and the reciprocal of the corresponding absolute temperature (Arrhenius Law). For the plastics tested, no transition, in particular a first-order transition, s
30、hould occur in the temperature range under study. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
31、 revision, and parties to agreements based on this International Standard 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 291:1977, Plastics
32、Standard atmospheres for conditioning and testing. IEC 216-1:1990, Guide for the determination of thermal endurance properties of electrical insulating materials Part 1: General guidelines for ageing procedures and evaluation of test results. IEC 216-2:1990, Guide for the determination of thermal en
33、durance properties of electrical insulating materials Part 2: Choice of the test criteria. IEC 216-3-1:1990, Guide for the determination of thermal endurance properties of electrical insulating materials Part 3: Instructions for calculating thermal endurance characteristics Section 1: Calculations u
34、sing mean values of normally distributed complete data. IEC 216-3-3:, Guide for the determination of thermal endurance properties of electrical insulating materials Part 3: Instructions for calculating thermal endurance characteristics Section 3: Calculations for incomplete data 1) . IEC 216-4-1:199
35、0, 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 thermal endurance properties of electrical insulating materials Part 5: Guidelines for the applicatio
36、n of thermal endurance characteristics. 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 relationship at a given time (normally200
37、00h) 1) To be published. 15B (B.C.) 82EN ISO2578:1998 4 BSI 03-2000 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 diagno
38、stic procedures in a comparative test 3.3 halving interval (HIC) number corresponding 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 endurance graph. It i
39、s not constant, but varies with temperature 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 lo
40、garithm of time to reach a specified end-point in a thermal endurance test is plotted versus the reciprocal thermodynamic (absolute) test temperature 3.5 threshold value value, corresponding to a percentage of the initial value of the property under investigation, at which the ageing test is stopped
41、 and the time to failure is calculated NOTE 1The level of 50%is often used to determine the threshold value. NOTE 2If 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 val
42、ue. 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 variati
43、ons in the numerical value of a chosen characteristic (for example, a mechanical, optical or electrical property) are determined as a function of time. The procedure is continued until the relevant threshold value of that characteristic has been reached, resulting in the time to failure at that part
44、icular temperature. Further specimens are exposed at least two other temperatures and the variations in the relevant characteristic determined. It is recommended to heat-age test specimens at three to four temperatures, and determine the time to failure for each of the temperatures. 4.2 Determinatio
45、n 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 20000h) gives the temperature index sought. 4.3 Use of correlation coefficient The reliability of the extrapolation of the graph d
46、epends 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 calculated in accordance with Annex B. If this calculation results in a v
47、alue smaller than0,95(for three test temperatures; see also IEC216), 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 plastic, its thermal endurance and the method of determination are of cen
48、tral importance. The reference plastic shall be of the same type as the tested plastic, and have a history of satisfactory service. It shall have a known temperature index for the property and a threshold value which are the same, or at least reasonably similar to, those to be employed in the RTI te
49、st. The TI and HIC of the reference material 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 from the supply roll, cutting of anisotropic material in the same direction, moulding, curing, preconditioning, etc. shall be performed in the same manner for both materials, and the specimens shall be tested in the same thickness.EN ISO2578:1998 BSI 03-2000
