BS 2782-5 Method 540G-1995 Methods of testing plastics - Optical and colour properties weathering - Methods of exposure to laboratory light sources - Open flame carbon-arc lamps《塑料.pdf

1、BRITISH STANDARD BS2782-5: Method540G: 1995 ISO4892-4: 1994 Methods of testing Plastics Part5: Optical and colour properties, weathering Method540G: Methods of exposure to laboratory light sources Open-flame carbon-arc lamps IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0

2、, Introduction, issued separately.BS2782-5:Method540G:1995 This British Standard, having been prepared under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15 September1995 BSI 08-1999 The following BSI refe

3、rences relate to the work on this standard: Committee reference PRI/21 Draft for comment91/42187 DC ISBN 0 580 24503 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/21, Testing of plastics, upon which the following

4、bodies wererepresented: British Apparel and Textile Confederation British Plastics Federation British Telecommunications plc Department of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) Electrical and Electronic Insulation Associatio

5、n (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Institute of Materials Ministry of Defence Packaging and Industrial Films Association Pira International RAPRA Technology Ltd. Royal Society of Chemistry Amendments issued since publication Amd. No. Date CommentsBS2782-5:Method540G:1995 BSI 08-1999 i Contents Page

6、 Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Apparatus 1 5 Test specimens 2 6 Test conditions 2 7 Procedure 2 8 Exposure report 3 Annex A (normative) Specifications for light source 4 Annex B (informative) Information on filter el

7、ements used in carbon-arc lamps 4 Annex C (informative) Typical test apparatus 5 Figure C.1 5 Table 1 Spectral transmittance of glass filters at specific wavelengths prior to use 1 Table 2 Spray cycles 2 List of references Inside back coverBS2782-5:Method540G:1995 ii BSI 08-1999 National foreword Th

8、is British Standard has been prepared by Technical Committee PRI/21. It is identical with ISO4892-4:1994 Plastics Methods of exposure to laboratory light sources Part4: Open-flame carbon-arc lamps, published by the International Organization for Standardization (ISO). It is incorporated into BS2782

9、Methods of testing plastics Part11Thermoplastic pipes, fittings and valves, as Method540F:1995, for association with related test methods for plastics materials. Together with method540D:1995, method540E:1995 and method540F:1995, it constitutes a revision of BS2782-5:Method540B:1982 (which is identi

10、cal with ISO4892:1981), which is now obsolescent. This test method has been implemented for use for other fresh applications and to enable experience of the method to be gained for the revision or amendment of other national standards as practicable, but it should not be presumed to apply to any exi

11、sting standard or specification which contains or makes reference to a different edition or method until that standard/specification has been amended or revised to make reference to this method and adjust any requirements as appropriate. NOTEBecause the time scale necessary to reassess any correlati

12、ons between the use of the methods covered by ISO4892 and the effects of natural weathering may require at least2years, the1981 edition, as BS2782-5:Method540B:1982, will remain available as an obsolescent standard pending withdrawal as soon as a periodic review concludes that its retention is no lo

13、nger appropriate. WARNING. This British Standard, which is identical with ISO4892-4:1994, does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety at Work etc. Act1974. Attention should be paid to any appropriate safety precautions and the method sh

14、ould 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 Standard does not of itself confer immunity from legal obligation

15、s. Cross-references Publication referred to Corresponding British Standard BS2782 Methods of testing plastics Part5 Optical and colour properties, weathering: ISO4582:1980 Method552A:1981 Determination of changes in colour and variations in properties after exposure to daylight under glass, natural

16、weathering or artificial light (Identical) ISO4892-1:1994 Method540D:1995 Methods of exposure to laboratory light sources General guidance (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This

17、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.BS2782-5:Method540G:1995 BSI 08-1999 1 1 Scope This part of ISO4892 specifies methods for exposing specimens to open-flame carbon-arc lamps

18、. General guidance is given in ISO4892-1. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO4892. At the time of publication, the editions indicated were valid. All standards are subject to revision, and

19、parties to agreements based on this part of ISO4892 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. ISO4582:1980, Plastics Determination of chang

20、es in colour and variations in properties after exposure to daylight under glass, natural weathering or artificial light. ISO4892-1:1994, Plastics Method of exposure to laboratory light sources Part1: General guidance. 3 Principle 3.1 Specimens of the samples to be tested are exposed to a carbon-arc

21、 light source under controlled environmental conditions. 3.2 The procedure may include measurements of the irradiance and radiant exposure at the surface of the specimen. 3.3 It is recommended that a similar material of known behaviour be exposed simultaneously with the experimental material as a re

22、ference. 3.4 Intercomparison of results obtained from specimens exposed in different apparatus should not be made unless reproducibility has been established among devices for the material to be tested. 4 Apparatus 4.1 Laboratory light source 4.1.1 The lamp comprises an arc formed in free air betwee

23、n carbon rod electrodes. The specifications for the light source are given in Annex A. 4.1.2 The radiation reaching the specimens passes through filter elements. The different types of filterelement used in practice shall have spectral-transmittance values as specified in Table 1 at the wavelengths

24、given in the table. Information on different types of glass filter is given in Annex B. The carbon rods shall be changed in accordance with the manufacturers instructions. The characteristics of filters are subject to change during use due to ageing and the formation of deposits, and filters shall t

25、herefore be replaced at suitable intervals (see7.2.2). 4.2 Test chamber (see also Annex B) The test chamber contains a specimen frame, with provision for passing air over the specimens for temperature control. The frame rotates about the central axis of the carbon-arc holder. A typical frame diamete

26、r is96cm. Other frame diameters may be used if mutually agreed upon by all interested parties. The frame shall carry specimens directly as panels and/or in holders attached to the frame. The frame may be vertical or inclined. The upper and lower electrodes, as well as the filter(s), shall be install

27、ed in accordance with the instructions of the manufacturer of the apparatus. The apparatus shall be fitted with equipment for programming exposure cycles within the operational limits of the apparatus. 4.3 Radiometer When a radiometer is used, it shall comply with the requirements outlined in ISO489

28、2-1:1994, subclause5.2. Table 1 Spectral transmittance of glass filters at specific wavelengths prior to use Type1 Type2 Type3 Wavelength nm Transmittance % Wavelength nm Transmittance % Wavelength nm Transmittance % 255 u 1 275 u 2 295 u 1 302 71to86 320 65to80 320 W 40 W 360 91 400to700 W 90 400to

29、700 W 90BS2782-5:Method540G:1995 2 BSI 08-1999 4.4 Black-standard/black-panel thermometer The black-standard or black-panel thermometer used shall comply with the requirements outlined in ISO4892-1:1994, subclause5.1.5. 4.5 Relative-humidity control equipment The relative humidity of the air passing

30、 over the test specimens shall be controlled at an agreed value if required and measured by suitable instruments inserted into the test chamber and shielded from the lamp radiation. 4.6 Spray system 4.6.1 The test chamber shall contain a water-spray system equipped with nozzles to produce a uniforml

31、y distributed spray on demand. The system shall be constructed of stainless steel, plastic or another material that does not react with or contaminate the water passing through it. NOTE 1Suitable filters and demineralizers may be required for use in conjunction with the spray system in order to meet

32、 the requirements for water purity. 4.6.2 The spray system shall provide uniform wetting and rapid cooling. Spray water shall drain freely from the wetted surfaces. 4.6.3 Specimens may be sprayed with distilled or demineralized water (having a conductivity below54S/cm) intermittently under specified

33、 conditions. The water shall leave no observable stains or deposits and should therefore preferably contain less than1ppm of solids. In addition to distillation, a combination of deionization and reverse-osmosis can be used to produce water of the required quality. The pH of the water used shall be

34、reported. 4.6.4 A spray system designed to cool the specimen by spraying the back surface of the specimen or specimen backing may be required when the exposure programme specifies periods of condensation. 4.7 Specimen holders Specimen holders may be in the form of an open frame, leaving the back of

35、the specimen exposed, or they may provide the specimen with a solid backing. They shall be made from inert materials that will not affect the test results, for example non-oxidizing alloys of aluminium or stainless steel. Brass, steel or copper shall not be used in the vicinity of the test specimens

36、. The backing used may affect the test results particularly with transparent specimens, and therefore shall be agreed on between the interested parties. 4.8 Apparatus to assess changes in properties The apparatus required by the International Standards relating to the determination of the properties

37、 chosen for monitoring (see also ISO4582) shall be used. 5 Test specimens Refer to ISO4892-1. 6 Test conditions 6.1 Black-panel/black-standard temperature Unless otherwise specified, the black-panel temperature shall be63 C 3 C. If a black-panel thermometer is used, then the type of thermometer, the

38、 way in which it is mounted on the specimen holder and the selected temperature of operation shall be stated in the exposure report. If a water spray is used, the temperature requirement applies to the end of the dry period. 6.2 Relative humidity Unless otherwise specified, the relative humidity sha

39、ll be (50 5)%. NOTE 2The relative humidity of the air as measured in the test chamber is not necessarily equivalent to the moisture content of the air very close to the specimen surface owing to the different temperatures of test specimens having different colours and thicknesses. 6.3 Spray cycle Th

40、e spray cycle used shall be as agreed between the interested parties, but should preferably be one of the cycles given in Table 2. Table 2 Spray cycles 6.4 Cycles with dark periods The conditions in6.1 to6.3 are valid for continuous presence of radiant energy from the source. More complex cycles may

41、 be programmed including dark periods that allow high relative humidities and the formation of condensate at elevated chamber temperatures. Such programmes shall be given, with full details of the conditions, in the exposure report. 7 Procedure 7.1 Mounting the test specimens Attach the specimens to

42、 the specimen holders in the equipment in such a manner that the specimens are not subject to any applied stress. Identify each test specimen by suitable indelible marking, avoiding areas to be used for subsequent testing. As a check, a plan of the test-specimen positions may be made. Duration of sp

43、raying min Dry interval between spraying min 18 0,5 102 0,5 12 0,5 48 0,5BS2782-5:Method540G:1995 BSI 08-1999 3 If desired, in the case of specimens used to determine change in colour and appearance, a portion of each test specimen may be shielded by an opaque cover throughout the test. This gives a

44、n unexposed area adjacent to the exposed area for comparison. This is useful for checking the progress of the exposure, but the data reported shall always be based on a comparison with control specimens stored separately in the dark. 7.2 Exposure Before placing the specimens in the test chamber, be

45、sure the apparatus is operating under the specified conditions (see clause6). Maintain these conditions throughout the exposure. 7.2.1 Mount the test specimens on the specimen frame both above and below the horizontal centreline of the source of radiation. To ensure uniform irradiation over the whol

46、e of the specimen surface, specimens shall be repositioned vertically in a sequence which will ensure that each specimen has equivalent exposure periods in each location. When the exposure interval does not exceed24h, each specimen shall be located equidistant from the horizontal axis of the arc. Fo

47、r exposure intervals not exceeding100h, daily rotation of the specimens is recommended. Other methods of achieving uniform radiant exposure may be employed if mutually agreed on by the interested parties. 7.2.2 Replace filters after2000h of use, or when pronounced discoloration or milkiness develops

48、, whichever occurs first. Clean the filters, at intervals recommended by the manufacturer, with a clean, dry, non-abrasive cloth or towel, or with a solution of detergent and water followed by rinsing with clean water. It is recommended that filters be replaced on a rotating schedule in order to pro

49、vide more uniformity over long periods of exposure. In such cases, replace the filters sequentially, in pairs, every500h. Monitor the age and position of the filter panes so that the oldest pair is removed each time. 7.3 Measurement of radiant exposure If used mount the light-dosage measurement instrument so that the radiometer indicates the irradiance at the exposed surface of the test specimen. The exposure interval shall be expressed in terms of incident spectral radiant energy per unit area of the exposure plane, in joules per square metre