1、BRITISH STANDARD BS 2782-1: Method153B: 1991 ISO458-2: 1985 Methods of testing Plastics Part1: Thermal properties Method153B: Determination of stiffness in torsion of flexible materials (method for vinyl chloride compounds) IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0,
2、 Introduction, issued separately.BS2782-1:Method153B:1991 This British Standard, having been prepared under the directionof the Plastics andRubber Standards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 29November1991 BSI09-1999 The following BSI
3、references relate to the work on this standard: Committee reference PRM/21 Draft for comment 83/51069 DC ISBN 0 580 20161 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technic
4、al Committee PRM/21, upon 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 L
5、aboratory) EEA (The Association 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
6、Plastic Industrial Containers Association Plastics and Rubber Institute PIRA International RAPRA Technology Ltd. Yarsley Technical Centre Ltd. Amendments issued since publication Amd. No. Date CommentsBS2782-1:Method153B:1991 BSI 09-1999 i Contents Page Committees responsible Inside front cover Nati
7、onal foreword ii 0 Introduction 1 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Equipment 1 5 Test specimens 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Publication(s) referred to Inside back coverBS2782-1:Method153B:1991 ii BSI 09-1999 National foreword This British
8、 Standard has been prepared under the direction of the Plastics and Rubber Standards Policy Committee and is identical with ISO458-2:1985 “Plastics Determination of stiffness in torsion of flexible materials Part2:Application to plasticized compounds of homopolymers and copolymers of vinyl chloride”
9、, published by the International Organization for Standardization (ISO). WARNING NOTE. This British Standard, which is identical with ISO458-2, 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
10、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 British Standard d
11、oes not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO458-1:1985 BS2782 Methods of testing plastics Method153A:1991 Determination of stiffness in torsion of flexible materials (general method) (Identical) Summary of pages
12、This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2, 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 the inside front cover.BS2782
13、-1:Method153B:1991 BSI 09-1999 1 0 Introduction In the case of compositions based on plasticized polyvinyl chloride, all the curves for the logarithm of the stiffness in torsion as a function of temperature have a similar appearance, in the form of a reversed S. Each curve is essentially characteriz
14、ed by three regions: a) two extreme regions, where the change in the stiffness as a function of temperature occurs relatively slowly: 1) a region of elevated values, corresponding to a high degree of rigidity, attributed by some authors to a loss of elastic properties. The value of the stiffness in
15、torsion was taken arbitrarily by Clash and Berg 1)as3,1 10 9 dyn/cm 22) , 2) a region of low values, corresponding to a high degree of flexibility. In this case the corresponding stiffness in torsion has been arbitrarily taken as42kgf/cm 23)representing an appropriate value for films having a suffic
16、ient degree of flexibility at normal use temperature to render them suitable for the production of curtains, drapes and waterproof materials; b) an intermediate region where the change in the stiffness is generally more rapid and where the curve exhibits an inflection. This region has been arbitrari
17、ly allotted the value of233kgf/cm 24)as stiffness in torsion. With allowance for the precision of the tests, the characteristic values for the stiffness in torsion can therefore be represented as: 1 Scope and field of application This part of ISO458 specifies a method for determining the temperature
18、s corresponding to three conventional characteristic values for the stiffness in torsion of plasticized compounds of homopolymers and copolymers of vinyl chloride. 2 Reference ISO458-1, Plastics Determination of stiffness in torsion of flexible materials Part1: General method. 3 Principle Use of ISO
19、458-1 for plasticized compounds of homopolymers and copolymers of vinyl chloride, consisting of determining, according to a special case of method A with an angle of deflection between55 and65 , the temperatures corresponding to three characteristic values of the stiffness in torsion (T), i.e.:300MP
20、a,23MPa and4MPa. 4 Equipment See ISO458-1. 5 Test specimens To construct a curve showing the same deformation of the test specimen at the characteristic points, the following test specimens are required: a) one test specimen(1) with thickness between1,8 and2mm for determining the section of the curv
21、e in the region300MPa; b) one test specimen(2) with thickness between2 and5mm for determining the section of the curve in the region23MPa; c) one test specimen(3) with thickness between4 and5mm for determining the section of the curve in the region4MPa. All test specimens shall be60 2mm in length an
22、d6,2 to6,4mm in width. NOTE 1For the purpose of a rapid test it is possible to use a single test specimen between4 and5mm thick for constructing the sections of the curve passing through the points23MPa and4MPa. NOTE 2Certain properties of plastics and, in particular, the properties involved in this
23、 test method can change slightly on storage. It is therefore recommended to record the dates of preparation of test specimens, and in comparing samples to store the specimens for at least48h before testing. 6 Procedure 6.1 Selection of applied torque Use the formula (see ISO458-1 for definitions and
24、 units) 1) Clash, R.F., and Berg, R.M., Vinyl elastomers: low temperature flexibility behaviour, Industrial and Eng. Chem. 34, pp.12181222(1942). 2) 3,110 9 dyn/cm 2 =310MPa 3) 42kgf/cm 2 =4,1MPa 4) 233kgf/cm 2 =22,8MPa 300MPa 23MPa 4MPa Tk M - =BS2782-1:Method153B:1991 2 BSI 09-1999 to calculate th
25、e applied torques M 1 , M 2 , M 3to be used with test specimens(1),(2),(3), respectively, to give an angle of deflection of60 5 for each of the three characteristic values of T: 6.2 Selection of temperatures Select as the initial temperatures a multiple of5 C corresponding essentially to the maximum
26、 level of the stiffness value. In the absence of the required data, select40 C. 6.3 Measurement 6.3.1 Follow the instructions of method A specified in ISO458-1, with a40mm span, using test specimen(1) and the additional weights needed to obtain the applied torque M 1as calculated in accordance with6
27、.1. Record the temperature to the nearest1 C and the corresponding value of the angle of deflection to the nearest1 . If the angle of deflection is greater than65 , proceed to a new test using a different test specimen, starting with a lower temperature. If the angle of deflection is less than55 , i
28、ncrease the temperature by5 C and proceed with the test. Repeat the above operation so as to obtain at least three valid tests. 6.3.2 Repeat the same operations using test specimen(2) and applied torque M 2 . 6.3.3 Repeat the same operations using test specimen(3) and applied torque M 3 . 7 Expressi
29、on of results Plot the logarithm of the values of stiffness in torsion versus temperature. Note on the curve the temperatures corresponding to the three conventional characteristic stiffnesses in torsion:300MPa,23MPa and4MPa. 8 Test report The test report shall include the following particulars: a)
30、a reference to this part of ISO458; b) the particulars specified in clause8 of ISO458-1; c) temperatures corresponding to the three conventional characteristic values of stiffness in torsion of plasticized PVC compounds:300MPa,23MPa and4MPa. T 1 = 300MPa T 2 = 23MPa T 3 = 4MPaBS2782-1:Method153B:199
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