BS 2782-1 Method 130A-1991 Methods of testing plastics - Thermal properties - Determination of the thermal stability of polyvinyl chloride by the Congo red method《塑料试验方法 第1部分 热性能 试.pdf

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1、BRITISH STANDARD BS2782-1: Method130A: 1991 ISO182-1: 1990 Methods of testing Plastics Part 1: Thermal properties Method 130A: Determination of the thermal stability of polyvinyl chloride by the Congo red method IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0, Introductio

2、n, issued separately.BS2782-1:Method 130A:1991 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 30April 1991 BSI 08-1999 First published (as a revisio

3、n of method109A of BS2782:1970) September1976 Second edition April1991 The following BSI references relate to the work on this standard: Committee reference PRM/21 Draft for comment89/41649 DC ISBN0580195937 Committees responsible for this British Standard The preparation of this British Standard wa

4、s entrusted 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 Steel Industry British Telecommunications plc Department of Trade and Industry (National Physical Laboratory)

5、 EEA (the Association of Electronics, Telecommunications and Business Equipment Industries) Electrical and Electronic Insulation Association (BEAMA Ltd.) Electrical Installation Equipment Manufacturers Association (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Man-made Fibres Producers Committee Ministry of Defe

6、nce PIRA Packaging and Industrial Films Association Plastic Industrial Containers Association Plastics and Rubber Institute RAPRA Technology Ltd. Standards Association of Australia Yarsley Technical Centre Ltd. The following bodies were also represented in the drafting of the standard, through subco

7、mmittees and panels: ERA Technology Ltd. Home Office Society of Motor Manufacturers and Traders Limited Amendments issued since publication Amd. No. Date CommentsBS2782-1:Method 130A:1991 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative

8、 references 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Preparation of test portions 2 7 Number of tests 3 8 Temperatures for dehydrochlorination 3 9 Procedure 3 10 Expression of results 3 11 Precision 3 12 Test report 3 Figure 1 Arrangement of the test tube in the oil bath 2 Publication(s) referre

9、d to Inside back coverBS2782-1:Method 130A:1991 ii BSI 08-1999 National foreword This method has been prepared under the direction of the Plastics and Rubber Standards Policy Committee and is identical with ISO182-1:1990 “Plastics Determination of the tendency of compounds and products based on viny

10、l chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures Part1: Congo red method”, published by the International Organization for Standardization (ISO). It is a revision of BS2782:Method 130A:1976 which is withdrawn. In5.4, common pra

11、ctice in the UK is to ensure a depth of at least 50mm in the oil bath. Users of the test should also note that the method differs from DIN57472:1985 “Heat stability test for polyvinyl chloride” although using the same test temperature. The Technical Committee has reviewed the provisions of ISO565:19

12、90, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this method. A related British Standard for ISO565:1990 is BS410:1986 “Specification for test sieves”. WARNING NOTE. This British Standard method, which is identical with ISO182-2, does n

13、ot 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 should be operated only by trained personnel. A British Standard does not purport to include all th

14、e 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 obligations. Cross-references International standard Corresponding British Standard ISO3696:1987 BS3978:198

15、7 Specification for water for laboratory use (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. Th

16、is will be indicated in the amendment table on the inside front cover.BS2782-1:Method130A:1991 BSI 08-1999 1 WARNING The use of this part of ISO182 may involve hazardous materials, operations and equipment. This part of ISO182 does not purport to address all of the safety problems associated with it

17、s use. It is the responsibility of the user of this part of ISO182 to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope 1.1 This part of ISO182 specifies a method for the determination of the thermal stability at elevate

18、d temperature of compounds and products based on vinyl chloride homopolymers and copolymers (in the following text abbreviated to PVC) which undergo dehydrochlorination (the evolution of hydrogen chloride). 1.2 The method is intended primarily as a simple and rapid quality-control test during the ma

19、nufacture and conversion of PVC compounds. It may be used also for the characterization of PVC compounds and products. It is suitable for coloured compounds and products where a discolouration test under the action of heat may be unsatisfactory. 1.3 The method is recommended for compounded materials

20、 and products only. It is not recommended for compounds in the form of dry blends since such materials may not be sufficiently homogeneous. PVC compounds and products may evolve decomposition products in addition to hydrogen chloride at elevated temperatures. A limited number of these decomposition

21、products may affect the time to colour change of the indicator paper. It is not possible to compensate for this effect within the scope of this part of ISO182, and therefore care is necessary in comparing results for dissimilar compounds and products. 2 Normative references The following standards c

22、ontain provisions which, through reference in this text, constitute provisions of this part of ISO182. 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 ISO182 are encouraged to investigate the possib

23、ility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO565:1990, Test sieves Metal wire cloth, perforated metal plate and electroformed sheet Nominal sizes of openings. ISO3696:1987, Water

24、for analytical laboratory use Specification and test methods. 3 Principle A test portion of the PVC compound or product is maintained at an agreed temperature in still air until the colour of a Congo red paper held above it changes from red to blue. If universal indicator paper is used, the relevant

25、 colour change is that corresponding to pH3. The time required for the colour change is taken to be the stability time, t s . 4 Reagents 4.1 Congo red indicator paper Commercial Congo red paper is suitable, providing that it is available in10mm width. The paper may also be prepared by immersingstrip

26、s of filter paper,10mm wide, in a0,15%(m/m) solution of Congo red in methanol, and drying. 4.2 Universal indicator paper, in roll form, with a pH range of1 to10, shall be used. The paper shall be provided with a colour scale in order to interpret the changes in pH. 5 Apparatus 5.1 Test tubes, with t

27、he following dimensions: Stoppers are required with holes through the centres which provide an interference fit for the glass tubes(5.2). The complete arrangement is shown inFigure 1. 5.2 Small glass tubes,2mm to3mm in internal diameter and approximately100mm long (seeFigure 1). 5.3 Oil bath, with a

28、 capacity of at least10litres. The bath shall be capable of operating in the temperature range170 C to210 C and of maintaining the test temperature with an accuracy of 0,5 C throughout the working volume. 5.4 Heat-resistant insulating shield, drilled to permit the insertion of test tubes(5.1) and po

29、sitioned to permit the suspension of the tubes in the hot oil bath(5.3) to a depth of approximately50mm. 5.5 Thermometer, provided with a scale convenient for reading the oil bath temperature in the range170 C to 210 C and with a scale division of0,1 C. 5.6 Stopclocks, two or four stopclocks are req

30、uired, depending on the parameters to be measured (see9.6). external diameter: approximately17mm wall thickness: approximately0,4mm length, minimum: 150mmBS2782-1:Method130A:1991 2 BSI 08-1999 6 Preparation of test portions The measured stability times depend to some extent on the surface area of th

31、e prepared test portions as well as on their thermal history. Any cutting or grinding of a material necessary to produce the test portions shall be carried out in a uniform manner. Heating of the material during grinding shall be avoided. 6.1 PVC plastisols Spread these materials on glass plates and

32、 gel in an oven at an agreed temperature so that sheets0,5mm thick are formed. Cut these sheets into squares with sides approximately2mm long. 6.2 PVC pellets, extrudates, mouldings, thick sheet, etc. Cut or grind these materials so that more than80% of the material passes through a2,0mm sieve (ISO5

33、65,R20/3 series) and an adequate amount is retained on a1,4mm sieve to prepare the test portions. 6.3 PVC film and sheet Cut these materials into squares or cubes with sides no longer than2mm. 6.4 PVC coatings Separate these materials from the substrate and then treat as in6.2 or6.3. 6.5 Insulation

34、or sheathing of cables and conductors Cut thin slivers with the dimensions indicated in6.2. Figure 1 Arrangement of the test tube in the oil bathBS2782-1:Method130A:1991 BSI 08-1999 3 7 Number of tests For each sample, conduct at least two determinations, using two separate test tubes which are imme

35、rsed in the oil bath at the same time. 8 Temperatures for dehydrochlorination These are preferably: 200 C for unplasticized compounds and products; 200 C for compounds and products for cable insulation and sheathing; 180 C for other plasticized compounds and products. 9 Procedure 9.1 Place a quantit

36、y of the PVC material to be tested, prepared in accordance with the appropriate part of clause6, in a test tube(5.1) such that the tube is filled to a depth of about50mm. Fill a second test tube(5.1) in the same way. Shake each tube gently, taking care that the pieces do not form a compact mass or a

37、dhere to the walls of the test tube. 9.2 Preheat the oil bath(5.3) to near the agreed test temperature, and adjust to the exact test temperature as indicated by the thermometer(5.5). 9.3 For each test tube, cut out or select a strip of the chosen indicator paper(4.1 or4.2)30mm long and10mm wide. Rol

38、l or fold one end of the indicator paper strip and insert it into the glass tube(5.2). Wet the indicator strip with grade2 water as defined in ISO3696. Insert the glass tube into the stopper. Slide the glass tube into the test tube, close the test tube with the stopper and adjust the position of the

39、 glass tube in the stopper so that the lower edge of the paper is located25mm above the top of the test portion. 9.4 Immerse each test tube in the oil bath to the level of the upper surface of the test sample, starting a stopclock(5.6) for each test tube. 9.5 Stop the stopclock for each of the test

40、determinations when there is the first clear sign of a change from red to blue in the Congo red indicator paper. When using universal indicator paper, the end point shall correspond to the colour indicating pH3. 9.6 When certain stabilizers are used in the PVC composition, the colour change is slow

41、and not very distinct. In this case, when using Congo red indicator paper, record two different times, corresponding to the first sign of colour change from red to violet and then the permanent change from violet to blue. Four stopclocks are required to conduct the test in these circumstances. 10 Ex

42、pression of results Record the time(s), in minutes, for each of the two determinations. The arithmetic mean of these values is the stability time t s . When two values differ by more than 10% from the mean, the results shall be discarded and the test repeated. 11 Precision The precision of this test

43、 method is not known because inter-laboratory data are not available. This method is not for use in specifications or in the case of disputed results as long as these data are not available. 12 Test report The test report shall include the following information: a) a reference to this part of ISO182

44、; b) the nature, form and designation of the PVC product sample; c) if appropriate, the manufacturer, where sampled and the degree of comminution of the specimen; d) the test temperature; e) the stability time t s , in minutes, to the nearest half-minute (include the individual values and the arithm

45、etic mean); f) in the case of slow colour changes in the indicator paper, the two times recorded in9.6 (again, include the individual values and the arithmetic mean); g) the date of the test.4 blankBS2782-1:Method130A:1991 BSI 08-1999 Publication(s) referred to See national foreword.BS2782-1: Method

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