BS 4370-3-1988 Methods of test for rigid cellular materials - Methods 12 and 13《硬质微孔材料试验方法 第3部分 方法12和13》.pdf

1、BRITISH STANDARD BS4370-3: 1988 Methods of test for Rigid cellular materials Part3: Methods12 and13 UDC678405.8:678.077:678.01BS4370-3:1988 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Committees, was published under the authority of the Board o

2、f BSI and comes intoeffect on 29 February 1988 BSI 04-1999 First published March1974 First revision February1988 The following BSI references relate to the work on this standard: Committee reference PLM/RUM/10 Draft for comment86/36513DC ISBN 0 580 16038 6 Committees responsible for this British Sta

3、ndard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Committees (PLM/RUM/-) to Technical Committee PLM/RUM/10, upon which the following bodies were represented: British Plastics Federation British Railways Board British Rigid Urethane Foam Manufacturers A

4、ssociation British Rubber Manufacturers Association Department of the Environment (Building Research Establishment) Furniture Industry Research Association Furniture, Timber and Allied Trades Union Ministry of Defence National Bedding Federation Phenolic Foam Manufacturers Association RAPRA Technolo

5、gy Ltd. Society of British Aerospace Companies Limited Society of Motor Manufacturers and Traders Limited Amendments issued since publication Amd. No. Date of issue CommentsBS4370-3:1988 BSI 04-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Method12. Determina

6、tion of friability 1 3 Method13. Determination of the coefficient of linear thermal expansion at low temperatures 2 Appendix A Suitable apparatus for method13 7 Figure 1 Friability test apparatus 2 Figure 2 Possible practical arrangement for friability test 3 Figure 3 Suitable apparatus for determin

7、ation of coefficient of linear thermal expansion at low temperatures 4 Figure 4 Layout of suitable cooling system for method13 5 Figure 5 Fiducial lines for method13 5 Publications referred to Inside back coverBS4370-3:1988 ii BSI 04-1999 Foreword This Part of BS4370 has been prepared under the dire

8、ction of the Plastics and Rubber Standards Committees and is a revision of BS4370-3:1974, which is withdrawn. The methods of test described here are intended to apply to rigid cellular products of polymeric origin, but they are not necessarily suitable for testing cellular materials of inorganic ori

9、gin. In this revision the method for the measurement of heat distortion temperature (formerly method11) has been withdrawn. Method12 has been amended to use less cumbersome and less noisy equipment. Method13 has now been aligned with method A of the corresponding international standard ISO4897. Many

10、 rigid cellular products and test specimens are not isotropic. This is usually ascribed to the fact that the cells in the material are elongated in a particular direction. This direction is referred to in this standard as the direction of anisotropy. Tests carried out in this direction usually give

11、results differing in magnitude from those carried out in other directions. The direction of anisotropy may vary from place to place in a product, hence the number of test specimens required in product specifications may be greater than those given herein. A British Standard does not purport to inclu

12、de 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 inside front cover, pages

13、i and ii, pages1 to8, 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 theinside front cover.BS4370-3:1988 BSI 04-1999 1 1 Scope This Part of BS4370 describes two meth

14、ods of test applicable to rigid cellular products of polymeric origin. NOTE 1The methods may not be suitable for testing products of inorganic origin. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Method12. Determination of friability 2.1 Ge

15、neral This method measures friability as the degree of disintegration of rigid cellular plastics calculated as the percentage mass loss, when subjected to a grinding process under specified conditions. 2.2 Apparatus 2.2.1 Ball mill, comprising a cylindrical polyethylene container of internal dimensi

16、ons90 1mm long and260 3mm in diameter (see Figure 1), into which are inserted3.8 0.1kg (i.e.approximately400) smooth porcelain balls each19.0 1.0mm in diameter, and a means of rotating the container with its longitudinal axis horizontal at a rate of622r/min. NOTE 1A suitable container may be constru

17、cted from polyethylene pipe of outside diameter280mm. Figure 2 shows an example of a suitable practical arrangement. NOTE 2Because of the high level of noise inherent with this apparatus, a sound enclosure is recommended. 2.2.2 Balance, reading to an accuracy of1mg. 2.2.3 Stop watch or stop clock, r

18、eading to an accuracy of1s. 2.3 Test specimen The test specimen shall be a cube of side20 1mm. The test specimen shall be free from surface skins. All debris remaining on the test specimen shall be removed using a vacuum cleaner. If required, the removal of debris from the specimen shall be assisted

19、 by an air jet which does not damage the specimen. Methods of specimen preparation employing heat (e.g.hot-wire cutting) shall not be used. 2.4 Number of test specimens Four test specimens are required for each test. Three tests shall be carried out. 2.5 Conditioning and temperature of test The test

20、 specimens shall be conditioned at23 2 C and50 5% r.h. for not less than16h. The tests shall be carried out immediately after conditioning. 2.6 Procedure Determine the mass of the set of four test specimens to the nearest1mg. Load the set of four specimens into the ball mill and secure the lid. Run

21、the apparatus for60 revolutions of the polyethylene container. Carefully remove the test specimens from the polyethylene container. Remove any debris from the specimens using a vacuum cleaner, assisting the process, if necessary, by using an air jet which does not damage the specimens. Redetermine t

22、he mass of the set of test specimens to the nearest1mg. If by visual inspection any of the four test specimens appear to have been non-uniformly abraded, or if a specimen breaks, abandon the test and prepare new test specimens. Clean the equipment after carrying out six tests, or earlier if the cont

23、ainer and balls become visibly contaminated. Do this by covering the balls with water, adding approximately20g of mild abrasive powder and grinding for at least1h. Rinse the container and balls thoroughly and dry them before re-use. 2.7 Calculation of results Calculate the friability F (in%) of the

24、set of test specimens using the following equation: where Calculate the mean friability (in%) of the material from the values obtained for the three tests. 2.8 Test report The test report shall include the following information: a) the description and identity of the material; b) the friability of e

25、ach set of test specimens (in%); c) the mean friability calculated from the values obtained for the three tests (in%); d) any deviation from the procedure described in this method; e) the method used, i.e.method12 of BS4370-3:1988. M o is the original mass of the set of test specimens (ing); M t is

26、the final mass of the set of test specimens (ing). F 100 M o M t M o - =BS4370-3:1988 2 BSI 04-1999 3 Method13. Determination of the coefficient of linear thermal expansion at low temperatures NOTEThis method is related to method A of ISO4897:1985. 3.1 General The coefficient of linear thermal expan

27、sion calculated as the change in unit length per degree Celsius change in temperature is measured by comparing the length of the test specimen with that of a reference length under controlled conditions at several temperatures between+23C and60C. The values obtained in this test should not be used t

28、o predict the behaviour of the test materials at temperatures outside the range of those covered in the test. The test is not designed to give information about long-term exposure to low temperatures which may alter the measured coefficient of thermal expansion. Care should be taken in applying the

29、value obtained in this test to calculate the overall coefficient of expansion of composite products of which the material under test is a part. NOTEAttention is drawn to method5 of BS4370-1:1988 which is a dimensional stability test and therefore covers irreversible changes. 3.2 Apparatus 3.2.1 Test

30、 chamber and cooling system. The test chamber shall consist of a well insulated box of approximate dimensions400mm 1000mm 150mm, having viewing windows900 10mm apart. These windows shall be insulated with plugs of insulation between readings to ensure a good temperature distribution as described in3

31、.6. NOTE 1A suitable chamber and cooling system are described in Appendix A and shown in Figure 3 and Figure 4. NOTE 2Liquid nitrogen has been found in practice to be the most satisfactory coolant. 3.2.2 Reference length,8805mm long, positioned inside the test chamber so that fiducial marks on the e

32、nd are at the same level and in the same vertical plane as fiducial lines on the test specimen, and adequately supported to prevent bowing (see Figure 5). NOTEThe coefficient of expansion of the reference length material should be small and accurately known. A suitable material is silica in the form

33、 of a rod with ends ground to knife edges. 3.2.3 Travelling microscope or equivalent apparatus capable of measuring to0.01mm. Ensure that the direction of travel of the instrument is parallel to the edge of the test specimen; any divergence shall be less than one degree of one arc. Figure 1 Friabili

34、ty test apparatusBS4370-3:1988 BSI 04-1999 3 3.2.4 Temperature measuring devices, calibrated over the required range to within1C. 3.3 Temperature measurement Temperatures in the test chamber shall be measured by any suitable means in at least five positions equally spaced along the length of the tes

35、t specimen. 3.4 Test specimen The test specimen shall be a rectangular board having the following dimensions: 900 mm long; 100mm to300mm wide; 25mm to50mm thick. The test specimen shall be cut without significant deformation of the original cell structure; the surfaces shall be parallel and unbowed

36、and free of surface skins. Hot wire cutting is not permissible. Fiducial lines shall be fixed to each end of the board. NOTEThese may consist, for example, of razor blades attached rigidly to the corners by drawing pins so that the knife edges project beyond the edge of the specimen and perpendicula

37、r to its length (see Figure 5). Figure 2 Possible practical arrangement for friability test + 20 0BS4370-3:1988 4 BSI 04-1999 3.5 Conditioning The test specimens shall be conditioned at23 2 C and50 5% r.h. for not less than16h. The test shall be carried out immediately after conditioning. 3.6 Proced

38、ure Determine the length of both the test specimen and the reference length in accordance with method1C of BS4370-1. Support the test specimen in the apparatus so that it does not sag and is free to move, and so that air may circulate freely round it. Position the ends of the specimen carrying the f

39、iducial lines centrally in the windows and symmetrically with respect to the reference length. Insert the temperature measuring devices and switch on the fan (if used). After the temperature has been steady within 2 C for30min, measure the difference in length between the test specimen and the refer

40、ence length. When the initial difference in length has been noted, adjust the thermostat to reduce the temperature by about20C and insert the plugs in the viewing holes. When the temperature is steady to within 2 C for20min at the new level again measure the difference between the length of the test

41、 specimen and the reference length. Repeat this measurement procedure at approximately5min intervals until three consecutive measurements agree to within0.03mm. Figure 3 Suitable apparatus for determination of coefficient of linear thermal expansionatlow temperaturesBS4370-3:1988 BSI 04-1999 5 Repea

42、t the procedure until the lowest temperature required is reached. Also make measurements as the apparatus is brought back to room temperature, observing the same precautions to establish thermal equilibrium. Check the temperature in the box before and after each measurement of length; the average of

43、 all of the readings shall be taken as the temperature to be associated with the length measured. The difference between the average temperatures immediately before and after measurement shall not exceed2C and the corresponding difference for any individual temperature measuring device shall not exc

44、eed50C. 3.7 Calculation of results Use the results obtained to plot a graph of the length of the test specimen against temperature. Make allowance for the (calculated) change in the length of the reference length. The results should all lie on a smooth curve and there should be no significant hyster

45、esis between descending and ascending temperature points. If there is significant hysteresis, repeat the determination allowing more time for the test specimen to attain thermal equilibrium. From the graph, read off the lengths of the specimen at the upper and lower temperatures of the range over wh

46、ich it is required to know the coefficient of linear thermal expansion. Calculate the mean coefficient of linear thermal expansion (inC) per degree Celsius at temperature T over the selected temperature range from the following equation: Figure 4 Layout of suitable cooling system for method13 Figure

47、 5 Fiducial lines for method13 L % L o - 1 T 1 T 2 - =BS4370-3:1988 6 BSI 04-1999 where It will be seen that: 3.8 Test report The test report shall include the following information: a) the description and identity of the material; b) the direction of any known anisotropy in relation to the measured

48、 length; c) the mean coefficient of linear thermal expansion to two significant figures; d) the mean temperature to which the results of3.8 c) relate; e) copy of the experimental graph; f) any deviation from the procedure described in this method; g) the method used, i.e.method13 of BS4370-3:1988. T

49、 1 is the higher temperature selected (inC); T 2 is the lower temperature selected (inC); L % is the change in length of the test specimen between temperatures T 1and T 2(inmm); L o is the original length of the test specimen at23 2 C (inmm). T T 1 T 2 + 2 - =BS4370-3:1988 BSI 04-1999 7 Appendix A Suitable apparatus for method13 NOTEA suitable apparatus is shown in Figure 3 and Figure 4. A.1 Test chamber, consisting of a box (see Figu