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1、BRITISH STANDARD BS 2782-4: Method 451B: 1978 Methods of testing Plastics Part 4: Chemical properties Method 451B: Determination of acetone-soluble matter in phenolic moulding materials after moulding IMPORTANT NOTE. Before reading this method it is essential to read the foreword, general introducti
2、on and instructions to BS 2782, issued separately. UDC 678.5/.8:678.01:543.832:678.632 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2782-4:Method 451B:1978 This British Standard, having been prepared unde
3、r the direction of the Plastics Standards Committee, was published under the authority of the Executive Board on 31 May 1978 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PLC/17 Draft for comment 77/50307 DC ISBN 0 580 10218 1 A British Standard do
4、es 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 obligations. Summary of pages This document comprises a front cover, an ins
5、ide front cover, pages i and ii, pages 1 and 2 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. Amendments issued since publication Amd. No.Date of issueComments Li
6、censed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2782-4:Method 451B:1978 BSI 11-1999i Contents Page 0Introduction1 1Scope1 2References1 3Principle1 4Reagents1 5Apparatus1 6Preparation of test sample1 7Procedure
7、1 8Expression of results2 9Test report2 Figure 1 Extraction apparatus2 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Tue Dec
8、 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2782-4:Method 451B:1978 BSI 11-19991 0 Introduction This method, which has been prepared under the direction of the Plastics Standards Committee, is technically similar to Method 451A:1978 except that it is used for determining whether a giv
9、en phenolic moulding material can be used to produce mouldings that contain not more than a relatively small amount of acetone-soluble matter. In this method, mouldings of specified dimensions are prepared under specified conditions from the moulding material under test and the acetone-soluble matte
10、r in these mouldings is determined in accordance with method 450A. This method replaces method 401B of BS 2782:1970, which is being withdrawn. WARNING NOTE. This method does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety at Work etc. Act 1974.
11、Attention should be paid to any appropriate safety precautions, and the method should only be operated by trained personnel. 1 Scope This method specifies a gravimetric method for the determination of the amount of matter that can be extracted by acetone, at a temperature near its boiling point, fro
12、m finely ground samples of mouldings prepared from a phenolic moulding material. The test for acetone-soluble matter is one means for determining the relative degree of cure of phenolic mouldings made from a given material. The process of extraction is carried out under specified conditions for a sp
13、ecified time. Although a high proportion of soluble matter is determined, extraction is not necessarily complete. The results are only comparative, because the extracted material normally contains substances other than any undercured resin that may be present, for example lubricants, colouring matte
14、r and plasticizers. 2 References The following standards publications are referred to in this method. BS 410, Specification for test sieves. BS 509, Acetone. BS 2648, Performance requirements for electrically-heated laboratory drying ovens. BS 2071, Soxhlet extractor. BS 2782, Methods of testing pla
15、stics Foreword, general introduction and instructions:1975. 3 Principle The principle of the method is the hot extraction of acetone-soluble matter from a test portion which has been reduced to a finely divided state. This is followed by evaporation of the acetone, drying of the extract to constant
16、mass and weighing of the dried extract. 4 Reagents The following reagent is required: 4.1 Acetone, complying with the requirements of BS 509. 5 Apparatus The following apparatus is required: 5.1 Means of reducing the moulded sample to a finely divided state. 5.2 Sieve, with nominal apertures of 425
17、4m, complying with the requirements of BS 410. 5.3 Sieve, with nominal apertures of 250 4m, complying with the requirements of BS 410. 5.4 Analytical balance, accurate to 0.001 g. 5.5 Extraction apparatus (see Figure 1) NOTEAlternatively, it is permissible to use a Soxhlet-type apparatus, complying
18、with the requirements of BS 2071, in which the material in the thimble is surrounded by the vapour of the boiling solvent. Any other extraction apparatus may be used, provided that it can be shown to give similar results. 5.6 Oven, circulating air type, capable of being controlled at 50 2 C (see BS
19、2648). 6 Preparation of test sample Mould two discs, each of 100 mm to 130 mm diameter and 6.5 0.5 mm thickness, using the conditions specified in the relevant British Standard for the material. Reduce the mouldings to powder by any suitable means, taking care that no undue heating of the material o
20、ccurs. Sieve separately the powder from each moulding using the two sieves of nominal apertures 425 4m and 250 4m respectively (5.2 and 5.3), keeping for extraction only those fractions which pass through sieve (5.2) and which are retained by sieve (5.3). Take precautions to avoid absorption of mois
21、ture by the powdered sample. 7 Procedure 7.1 Test one portion of the sieved material from each moulding (see clause 6). Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2782-4:Method 451B:1978 2 BSI 11-1999 7
22、.2 Weigh a test portion of approximately 3 g to the nearest 0.001 g into a tared open-textured quantitative filter paper or a single-thickness extraction thimble (5.5). 7.3 After folding over the thimble or filter paper containing the test portion so that none of the powder can float out, place it i
23、n the siphon of the extraction apparatus. Assemble the condenser, siphon tube and flask to which 50 ml of the acetone (4.1) has been added. NOTEIf a thimble is used, it may be closed with a plug of absorbent cotton wool to prevent the sample from floating out. 7.4 Regulate the heating so that siphon
24、ing takes place at a rate of 20 to 30 times per hour and continue the extraction for 6 h. At the end of this time remove the flask and pour the contents into a smaller flask or a small dish which has been weighed to the nearest 0.001 g. Wash the empty flask with about 20 ml of acetone and add the wa
25、shings to the extract. 7.5 Evaporate the acetone taking care that the temperature does not exceed 50 C. Place the vessel containing the residue in the oven (5.6) for 30 min at a temperature of 50 2 C. Then withdraw the vessel from the oven, allow it to cool in a desiccator to room temperature and we
26、igh. Repeat the operations of heating, cooling and weighing until constant mass is obtained, i.e. until the difference between two successive weighings does not exceed 0.003 g. 8 Expression of results The amount of acetone-soluble matter in the sample is given, as a percentage by mass, by the formul
27、a Take the arithmetic mean of the values obtained from the two test portions as the amount of acetone-soluble matter in the moulding under test. 9 Test report The test report shall include the following particulars. a) A complete identification of the material tested, including type source, manufact
28、urers code numbers, previous history, etc. b) A reference to this British Standard method, i.e. BS 2782:Method 451B:1978. c) The method used to reduce the moulding to a fine state of division. d) The amount of acetone-soluble matter in each test portion. e) The arithmetic mean of the values obtained
29、 from the two test portions. Figure 1 Extraction apparatus where mois the mass, in grams, of the test portion; m1is the mass, in grams, of the dry extract. m1 m0 - -100 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (
30、c) BSI blank Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 08:45:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2782-4: Method 451B: 1978 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsi
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