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1、AReference number ISO 4892-1:1999(E) INTERNATIONAL STANDARD ISO 4892-1 Second edition 1999-07-01 Plastics Methods of exposure to laboratory light sources Part 1: General guidance Plastiques Mthodes dexposition des sources lumineuses de laboratoire Partie 1: Guide gnral ISO 4892-1:1999(E) ISO 1999 Al
2、l 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. International Organization for Standardization Case
3、postale 56 CH-1211 Genve 20 Switzerland Internetisoiso.ch Printed in Switzerland ii Contents Page 1 Scope1 2 Normative references1 3 Terms and definitions .2 4 Principle2 4.1 Significance.2 4.2 Use of accelerated tests with laboratory light sources 3 5 Requirements for laboratory exposure devices.4
4、5.1 Light source 4 5.2 Temperature5 5.3 Humidity and wetting .6 5.4 Other apparatus requirements 7 6 Test specimens8 6.1 Form, shape and preparation 8 6.2 Number of test specimens.8 6.3 Storage and conditioning 9 7 Test conditions and procedure9 8 Precision and bias.9 8.1 Precision9 8.2 Bias 10 9 Te
5、st report10 Annex A (informative) Factors that decrease the degree of correlation between accelerated tests using laboratory light sources and actual-use exposures.12 Annex B (normative) Procedures for measuring the irradiance uniformity in the specimen exposure area14 ISOISO 4892-1:1999(E) iii Fore
6、word 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 techn
7、ical 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
8、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 requi
9、res approval by at least 75 % of the member bodies casting a vote. International Standard ISO 4892-1 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing, chemical and environmental resistance. This second edition cancels and replaces the first edition (ISO 4892-1:1994)
10、, of which it constitutes a technical revision. ISO 4892 consists of the following parts, under the general title Plastics Methods of explosure to laboratory light sources: Part 1: General guidance Part 2: Xenon-arc sources Part 3: Fluorescent UV lamps Part 4: Open-flame carbon-arc lamps Annex B for
11、ms a normative part of this part of ISO 4892. Annex A is for information only. ISO 4892-1:1999(E) ISO iv Introduction Plastics are often used outdoors or in indoor locations where they are exposed to daylight or to daylight behind glass for long periods. It is therefore very important to determine t
12、he effects of daylight, heat, moisture and other climatic stresses on the colour and other properties of plastics. Outdoor exposures to daylight and to daylight filtered by window glass are described in ISO 877:1994, Plastics Methods of exposure to direct weathering, to weathering using glass-filter
13、ed daylight, and to intensified weathering by daylight using Fresnel mirrors. However, it is often necessary to determine more rapidly the effects of light, heat and moisture on the physical, chemical and optical properties of plastics with accelerated laboratory exposure tests that use specific lab
14、oratory light sources. Exposures in these laboratory devices are conducted under more controlled conditions than found in natural environments and are designed to accelerate polymer degradation and product failures. Relating results from accelerated laboratory exposures to those obtained in actual-u
15、se conditions is difficult because of variability in both types of exposure and because laboratory tests often do not reproduce all the exposure stresses experienced by plastics exposed in actual-use conditions. No single laboratory exposure test can be specified as a total simulation of actual-use
16、exposures. The relative durability of materials in actual-use exposures can be very different depending on the location of the exposure because of differences in UV radiation, time of wetness, temperature, pollutants and other factors. Therefore, even if results from a specific accelerated laborator
17、y test are found to be useful for comparing the relative durability of materials exposed in a particular outdoor location or in particular actual-use conditions, it cannot be assumed that they will be useful for determining the relative durability of materials exposed in a different outdoor location
18、 or in different actual-use conditions. INTERNATIONAL STANDARD ISOISO 4892-1:1999(E) 1 Plastics Methods of exposure to laboratory light sources Part 1: General guidance 1 Scope 1.1 This part of ISO 4892 provides information and general guidance relevant to the selection and operation of the methods
19、of exposure described in detail in subsequent parts. It also describes and recommends procedures for determining irradiance and radiant exposure. Requirements for devices used to monitor chamber air temperature and surface temperature of dark and light materials are also described. 1.2 This part of
20、ISO 4892 also provides information on the interpretation of data from accelerated exposure tests. More specific information about methods for determining the change in plastic properties after exposure and reporting these results is described in ISO 4582. 2 Normative references The following normati
21、ve documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 4892. 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 4892 are encouraged
22、 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 291:199
23、7, Plastics Standard atmospheres for conditioning and testing. ISO 293:1986, Plastics Compression moulding test specimens of thermoplastic materials. ISO 294-1:1996, Plastics Injection moulding of test specimens of thermoplastic materials Part 1: General principles, and moulding of multipurpose and
24、bar test specimens. ISO 294-2:1996, Plastics Injection moulding of test specimens of thermoplastic materials Part 2: Small tensile bars. ISO 294-3:1996, Plastics Injection moulding of test specimens of thermoplastic materials Part 3: Small plates. ISO 295:1991, Plastics Compression moulding of test
25、specimens of thermosetting materials. ISO 2557-1:1989, Plastics Amorphous plastics Preparation of test specimens with a specified maximum reversion Part 1: Bars. ISO 2818:1994, Plastics Preparation of test specimens by machining. ISO 3167:1993, Plastics Multipurpose test specimens. ISO 4582:1998, Pl
26、astics Determination of changes in colour and variations in properties after exposure to daylight under glass, natural weathering or laboratory light sources. ISO 4892-2:1994, Plastics Methods of exposure to laboratory light sources Part 2: Xenon-arc sources. ISO 4892-3:1994, Plastics Methods of exp
27、osure to laboratory light sources Part 3: Fluorescent UV lamps. ISO 4892-1:1999(E) ISO 2 ISO 4892-4:1994, Plastics Methods of exposure to laboratory light sources Part 4: Open-flame carbon-arc lamps. ISO 9370:1997, Plastics Instrumental determination of radiant exposure in weathering tests General g
28、uidance and basic test method. CIE Publication No. 85:1989, Solar spectral irradiance. 3 Terms and definitions For the purposes of this part of ISO 4892, the following terms and definitions apply. 3.1 control weathering a material which is of similar composition and construction to the test material
29、 and which is exposed at the same time for comparison with the test material NOTE An example of the use of a control material would be when a formulation different from one currently being used is being evaluated. In that case, the control would be the plastic made with the original formulation. 3.2
30、 file specimen a portion of the material to be tested which is stored under conditions in which it is stable and is used for comparison between exposed and original state 3.3 reference material a material of known performance 3.4 reference specimen a portion of the reference material that is to be e
31、xposed 4 Principle Specimens of the samples to be tested are exposed to laboratory light sources under controlled environmental conditions. The methods described include means which may be used to measure irradiance at the face of the specimen and radiant exposure, and procedures for measuring the t
32、emperature of specified white and black panels. 4.1 Significance 4.1.1 When conducting exposures in devices which use laboratory light sources, it is important to consider how well the accelerated-test conditions simulate the actual-use environment for the plastic being tested. In addition, it is es
33、sential to consider the effects of variability in both the accelerated test and actual exposures when setting up exposure experiments, and when interpreting the results from accelerated exposure tests. 4.1.2 No laboratory exposure test can be specified as a total simulation of actual-use conditions.
34、 Results obtained from these laboratory accelerated exposures can be considered as representative of actual-use exposures only when the degree of rank correlation has been established for the specific materials being tested and when the type and mechanism of degradation are the same. The relative du
35、rability of materials in actual-use conditions can be very different in different locations because of differences in UV radiation, time of wetness, relative humidity, temperature, pollutants and other factors. Therefore, even if results from a specific exposure test conducted in accordance with ISO
36、 4892 are found to be useful for comparing the relative durability of materials exposed in a particular environment, it cannot be assumed that they will be useful for determining the relative durability of the same materials in a different environment. 4.1.3 Even though it is very tempting, calculat
37、ion of an “acceleration factor” relating “x” hours or megajoules of radiant exposure in an accelerated laboratory test to “y” months or years of actual exposure is not recommended. These acceleration factors are not valid for several reasons. ISOISO 4892-1:1999(E) 3 a) Acceleration factors are mater
38、ial-dependent and can be significantly different for each material and for different formulations of the same material. b) Variability in the rate of degradation in both actual-use and accelerated laboratory exposure tests can have a significant effect on the calculated acceleration factor. c) Accel
39、eration factors calculated based on the ratio of irradiance between a laboratory light source and daylight (even when identical bandpasses are used) do not take into consideration the effects of temperature, moisture and differences in spectral power distribution between the laboratory light source
40、and daylight. NOTE If use of an acceleration factor is desired in spite of the warnings given in this standard, such acceleration factors for a particular material are only valid if they are based on data from a sufficient number of separate exterior or indoor environmental tests and accelerated lab
41、oratory exposures so that results used to relate times to failure in each exposure can be analysed using statistical methods. An example of a statistical analysis using multiple laboratory and actual exposures to calculate an acceleration factor is described by J.A. Simms, in Journal of Coatings Tec
42、hnology, Volume 50, 1987, pages 45-53. 4.1.4 There are a number of factors that may decrease the degree of correlation between accelerated tests using laboratory light sources and exterior exposures (more specific information on how each factor may alter the stability ranking of materials is given i
43、n annex A): a) differences in the spectral distribution of the laboratory light source and daylight; b) light intensities higher than those experienced in actual-use conditions; c) exposure cycles that use continuous exposure to light from a laboratory light source without any dark periods; d) speci
44、men temperatures higher than those in actual conditions; e) exposure conditions that produce unrealistic temperature differences between light- and dark-coloured specimens; f) exposure conditions that produce very frequent cycling between high and low specimen temperatures, or that produce unrealist
45、ic thermal shock; g) unrealistically high or low levels of moisture; h) the absence of biological agents or pollutants. 4.2 Use of accelerated tests with laboratory light sources 4.2.1 Results from accelerated exposure tests conducted in accordance with this standard are best used to compare the rel
46、ative performance of materials. A common application of this is tests conducted to establish that the level of quality of different batches does not vary from that of a control material of known performance. Comparisons between materials are best made when the materials are tested at the same time i
47、n the same exposure device. Results can be expressed by comparing the exposure time or radiant exposure necessary to reduce the level of a characteristic property to some specified level. 4.2.1.1 It is strongly recommended that at least one control material be exposed with each test for the purpose
48、of comparing the performance of the test materials to that of the control. The control material should be of similar composition and construction and be chosen so that its failure modes are the same as that of the material being tested. It is preferable to use two controls, one with relatively good
49、durability and one with relatively poor durability. 4.2.1.2 Sufficient replicates of each control material and each test material being evaluated are necessary in order to allow statistical evaluation of the results. Unless otherwise specified, use a minimum of three replicates for all test and control materials. When material properties are measured using destructive tests, a separate set of specimens is needed for each exposure period. 4.2.2 In some specification tests, test materials