1、BRITISH STANDARD BS2782-1: Method153A: 1991 ISO458-1: 1985 Methods of testing Plastics Part1: Thermal properties Method153A: Determination of stiffness in torsion of flexible materials (general method) IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0, Introduction, issued
2、separately.BS2782-1:Method153A: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 31October1991 BSI 09-1999 The following BSI references relate to
3、the work on this standard: Committee reference PRM/21 Draft for comment80/51219 DC ISBN 0 580 20159 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/21, u
4、pon which the following bodies were represented: British Plastics Federation British Steel Industry British Telecommunications plc British Textile Confederation Department of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) EEA (The As
5、sociation of Electronics, Telecommunications and Business Equipment Industries) Electrical and Electronic Insulation Association (BEAMA Ltd.) Electrical Installation Equipment Manufacturers Association (BEAMA Ltd.) Ministry of Defence Packaging and Industrial Films Association Plastic Industrial Con
6、tainers Association Plastics and Rubber Institute PIRA International RAPRA Technology Ltd. Yarsley Technical Centre Ltd. Amendments issued since publication Amd. No. Date CommentsBS2782-1:Method153A:1991 BSI 09-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Sco
7、pe and field of application 1 2 References 1 3 Principle 1 4 Apparatus 1 5 Test specimens 1 6 Procedure 2 7 Expression of results 3 8 Test report 4 Figure Torsion tester 2 Table Values for as a function of b/d 3 Publication(s) referred to Inside back coverBS2782-1:Method153A:1991 ii BSI 09-1999 Nati
8、onal foreword This British Standard has been prepared under the direction of the Plastics and Rubber Standards Policy Committee and is identical with ISO458-1:1985 “Plastics Determination of stiffness in torsion of flexible materials Part1:General method”, published by the International Organization
9、 for Standardization (ISO). It supersedes BS2782-1:Method150A:1976 which is withdrawn. WARNING NOTE. This British Standard, which is identical with ISO458-1, does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety at Work, etc. Act1974. Attention s
10、hould 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 the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Brit
11、ish Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard BS2782 Methods of testing plastics ISO291:1977 Part0:1982 Introduction (Appendix A is identical) ISO458-2:1985 Method153B:1991 Determination of stiffness in
12、torsion of flexible materials (method for vinyl chloride compounds) (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendme
13、nts incorporated. This will be indicated in the amendment table on the inside front cover.BS2782-1:Method153A:1991 BSI 09-1999 1 1 Scope and field of application This part of ISO458 specifies a general method for determining the stiffness in torsion of flexible plastics at various temperatures, part
14、icularly at temperatures below0 C. 1) 2 References ISO291, Plastics Standard atmospheres for conditioning and testing. ISO458-2, Plastics Determination of stiffness in torsion of flexible materials Part2: Application to plasticized compounds of homopolymers and copolymers of vinyl chloride. 3 Princi
15、ple An observation of torque and angle of deflection is made after an arbitrarily fixed time of load application. This procedure is employed at single temperatures or at selected temperature intervals over a range specified for the material to be tested. NOTE 1It is necessary that the duration of lo
16、ad application be arbitrarily fixed and the values of angles of deflection be limited because of the known non-linear characteristics of plastics and their tendency to creep. NOTE 2Comparison between values of stiffness in torsion may be made only when the values have been obtained using test specim
17、ens of the same thickness and at the same span and approximately at the same angle of deflection. 4 Apparatus 4.1 Testing machine, capable of exerting a torque sufficient to deflect a test specimen with a span between35 and55mm. A schematic diagram of a machine suitable for this test is shown in the
18、 Figure. 4.2 Different weights, to vary the amount of torque depending on the stiffness of the specimen and its span. It is recommended that the actual amount of torque being applied by any given combination of weights, torque pulley and shaft bearings be determined by periodic calibration. NOTEFor
19、operation at low temperatures, it is recommended that the shaft of the machine be provided with a heated collar next to the lower bearing to prevent the formation of ice. 4.3 Dewar flask or thermal chamber of suitable dimensions. 4.4 Thermometer, accurate to1 C and having the necessary range. The bu
20、lb should be placed in close proximity to the test specimen. 4.5 Timer, accurate to0,1s. 4.6 Heat-transfer medium. For normal laboratory purposes, a substance which is liquid over the desired temperature range is used for the heat-transfer medium, provided it has been shown that the liquid does not
21、soften or otherwise affect the test specimen. With special precautions, a gaseous medium may be used (seenote1). Good stirring shall be ensured by appropriate means, during cooling and heating. NOTE 1Among the liquids found useful are acetone, ethanol, butanol, n-hexane, silicone oil and a mixture o
22、f methyl phosphate and water in the ratio of87 to13(V/V). For low temperatures to70 C a mixture by volume of50parts ethanol,30parts ethylene glycol and20parts water may be found useful. With a gaseous heat-transfer medium, care should be taken to ensure that sufficient time is allowed for the test s
23、pecimen to reach thermal equilibrium. NOTE 2For cooling, a refrigerator or a dry ice chest or both, according to the desired temperature, may be used. For heating, an electric heater may be used. 4.7 Micrometer. A dead-weight dial-type micrometer accurate to at least0,01mm shall be used for thicknes
24、s and width measurements. The pressure exerted on the specimen shall be within the limits of10 to30kPa. 2)An instrument accurate to at least0,1mm shall be used for measuring the span. 5 Test specimens 5.1 Dimensions Test specimens shall be70 10mm in length,6,0 to6,4mm in width, and may have two hole
25、s for fixing in the clamps of the machine. Such holes shall have elongated shapes in the direction of the length of the test specimen. In anisotropic sheet the test specimens shall be cut along the two main directions. The thickness of the test specimen shall be generally between1 and5mm. This range
26、 is usually sufficient to test materials of various stiffnesses. NOTEIn some cases it may be necessary to increase the width to13mm. 5.2 Number Two test specimens of each material shall be tested. 5.3 Conditioning Specimens to be tested shall be conditioned in accordance with ISO291. 1) SeeISO458-2
27、for application of the method to vinyl chloride polymers. Details necessary for testing other specific materials will form the subjects of subsequent parts of ISO458. 2) 1kPa=1kN/m 2BS2782-1:Method153A:1991 2 BSI 09-1999 6 Procedure 6.1 Measure the span. Measure the thickness and the width of the te
28、st specimen at three points along the span. If the individual values differ by more than0,1mm, the specimen shall be discarded and another specimen taken. Calculate the mean values of the thickness and the width. 6.2 Mount the test specimen in the machine(4.1). The test specimen shall be placed betw
29、een the clamps in such a way that its vertical axis coincides with the axis of rotation of the machine. Wedges may be used for this purpose. Figure Torsion testerBS2782-1:Method153A:1991 BSI 09-1999 3 NOTETo prevent effects of tension during cooling, it is recommended that the test specimen be fixed
30、 only when the temperature has fallen at least as low as the lowest point it is intended to study. 6.3 Place the thermometer(4.4) in position. 6.4 Fill the Dewar flask or the thermal chamber(4.3) with the heat transfer medium(4.6), the temperature of which should be somewhat below the lowest tempera
31、ture of the range to be studied. Place the flask in position on the machine. 6.5 Start the agitator. When the desired temperature and thermal equilibrium have been reached, take the first reading as described in6.7. 6.6 By intermittent use of the heater bring the test temperature above the initial t
32、est temperature, if applicable. 6.7 Take readings after the test specimen has been conditioned at each test temperature for. Weights shall be attached to give the required torque (M), calculated as M = RC W where D 1being the diameter, in millimetres, of the torque pulley, D 2being the diameter, in
33、millimetres, of the load cord, C W is the sum of the two weights, in newtons, used to apply the torque. A reading shall be taken by releasing the torque pulley and noting the angle of deflection, , after an interval of5s. The pulley shall then be returned to the zero position and, if applicable, the
34、 procedure shall be repeated at successively higher temperatures. The value of and the temperature shall be recorded for each reading. The testing shall be done in such a way that the angular deflection value falls within the range from10 to100 (method A), or from50 to60 (method B). If the value of
35、the angle of deflection does not fall within the range given above, the applied torque shall be varied in such a way as to produce a suitable reading. If this is found to be insufficient, a specimen of another thickness shall be taken for testing. NOTEResults obtained for a given material by methods
36、 A and B may differ from each other. 7 Expression of results 7.1 The stiffness in torsion, expressed as the apparent torsional modulus of elasticity T, for each temperature is given, in megapascals, by the equation or, in a modified form where L is the span, in millimetres; M is the applied torque,
37、in newton millimetres; b is the average width of the specimen (the larger cross-sectional dimension), in millimetres; d is the average thickness of the specimen (thesmaller cross-sectional dimension), in millimetres; if is a value depending on the ratio b/d; the Table gives the values for for variou
38、s ratios of b/d (intermediate values may be found by interpolation); is the angle of deflection, in degrees; 917 is a dimensional constant, in angular degrees; k is a factor depending on specimen dimensions, in angular degrees per cubic millimetre. The modified equation is recommended for use when r
39、epeated tests of the same specimen are being made. 7.2 If testing has been done over a wide range of temperatures, plot for each specimen tested the logarithm of stiffness in torsion versus temperature. Table Values for as a function of b/d 180 +15 0 s R D 1 D 2 + 2 - = Ratio b/d Ratio b/d 1,20 1,30
40、 1,40 1,50 1,60 1,70 1,80 1,90 2,00 2,25 2,64 2,82 2,98 3,13 3,26 3,37 3,48 3,57 3,66 3,84 2,50 2,75 3,00 3,50 4,00 4,50 5,00 5,50 6,00 6,50 3,99 4,11 4,21 4,37 4,49 4,58 4,66 4,72 4,77 4,81 NOTEThe values in the table are given by the equation BS2782-1:Method153A:1991 4 BSI 09-1999 8 Test report Th
41、e test report shall include the following information: a) a reference to this part of ISO458 and to the method selected (A or B); b) full details necessary for identification of the material, including name, stock or code number, date made, form, etc.; c) nominal dimensions of test specimen (span, w
42、idth, thickness); d) details of conditioning of test specimen prior to test; e) heat-transfer medium used; f) table of data and results (temperature, angular deflection, stiffness in torsion); g) plot of the logarithm of the mean value of stiffness in torsion for both test specimens versus temperatu
43、re (if a wide range of temperatures is used).BS2782-1:Method153A:1991 BSI 09-1999 Publication(s) referred to Seenational foreword.BS2782-1: Method153A: 1991 ISO458-1: 1985 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for pre
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