1、June 2015Translation by DIN-Sprachendienst.English price group 11No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 83
2、.060!%B3“2319116www.din.deDDIN ISO 812Rubber, vulcanized or thermoplastic Determination of low-temperature brittleness (ISO 812:2011),English translation of DIN ISO 812:2015-06Elastomere oder thermoplastische Elastomere Bestimmung der Kltesprdigkeitstemperatur (ISO 812:2011),Englische bersetzung von
3、 DIN ISO 812:2015-06Caoutchouc vulcanis ou thermoplastique Dtermination de la fragilit basse temprature (ISO 812:2011),Traduction anglaise de DIN ISO 812:2015-06SupersedesDIN ISO 812:2009-09www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprise
4、s 18 pages04.15 A comma is used as the decimal marker. Contents Page National foreword . 3 National Annex NA (informative) Bibliography 4 1 Scope 5 2 Normative references . 5 3 Terms and definitions . 6 4 Apparatus and materials . 6 5 Calibration . 8 6 Test pieces 8 7 Time interval between manufactu
5、re and testing 8 8 Procedure 9 8.1 Procedure A (determination of brittleness temperature) 9 8.2 Procedure B (determination of 50 % brittleness temperature) 9 8.3 Procedure C (testing at a specified temperature) . 10 9 Precision . 11 10 Test report . 11 Annex A (informative) Speed calibration of a so
6、lenoid-actuated low-temperature impact tester . 12 Annex B (normative) Calibration schedule . 15 Annex C (informative) Precision 17 2DIN ISO 812:2015-06National foreword This document (DIN ISO 812:2015) has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products” (Secretariat: DSM
7、, Malaysia). The responsible German body involved in its preparation was the DIN-Normenausschuss Materialprfung (DIN Standards Committee Materials Testing), Working Committee NA 062-04-34 AA Prfung der physika-lischen Eigenschaften von Kautschuk und Elastomeren. Attention is drawn to the possibility
8、 that some of the elements of this document may be the subject of patent rights. DIN and/or DKE shall not be held responsible for identifying any or all such patent rights. The DIN Standard corresponding to the International Standard referred to in this document is as follows: ISO 23529 DIN ISO 2352
9、9 Amendments This standard differs from DIN ISO 812:2009-09 as follows: a) Annex B (normative) “Calibration schedule” has been added; b) the unit for the clamping torque generated when tightening the test piece clamp has been corrected; c) the text of the standard has been editorially revised. Previ
10、ous editions DIN 53546: 1980-06 DIN ISO 812: 2004-06, 2009-09 3DIN ISO 812:2015-06National Annex NA (informative) Bibliography DIN ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods 4DIN ISO 812:2015-06WARNING Persons using this International St
11、andard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regul
12、atory conditions. IMPORTANT Certain procedures specified in this International Standard might involve the use or generation of substances, or the generation of waste, that could constitute a local environmental hazard. Reference should be made to appropriate documentation on safe handling and dispos
13、al after use. 1 Scope This International Standard specifies a method for determining the lowest temperature at which rubber materials do not exhibit brittle failure or the temperature at which half of the test pieces used in a test fail when impacted under specified conditions. The temperatures thus
14、 determined do not necessarily relate to the lowest temperature at which the material can be used since the brittleness will be affected by the conditions of test and especially by the rate of impact. Data obtained by this method should, therefore, be used to predict the behaviour of rubbers at low
15、temperatures only in applications in which the conditions of deformation are similar to those specified in the test. Three procedures are described: procedure A, in which the brittleness temperature is determined; procedure B, in which the brittleness temperature for 50 % failure is determined; proc
16、edure C, in which the test piece is impacted at a specified temperature. Procedure C is used in the classification of rubber materials and for specification purposes. NOTE A similar test for rubber-coated fabrics is described in ISO 4646, Rubber- or plastics-coated fabrics Low-temperature impact tes
17、t. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 18899:2004, Rubber
18、Guide to the calibration of test equipment ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods Rubber, vulcanized or thermoplastic Determinationof low-temperature brittleness 5DIN ISO 812:2015-063 Terms and definitions For the purposes of this do
19、cument, the following terms and definitions apply. 3.1 brittleness temperature lowest temperature at which none of a set of test pieces fractures due to low-temperature embrittlement when tested under the specified conditions 3.2 50 % brittleness temperature temperature at which 50 % of a set of tes
20、t pieces fracture due to low-temperature embrittlement when tested under the specified conditions 3.3 testing speed relative linear velocity at impact between the striking edge of the test apparatus and a clamped test piece 4 Apparatus and materials 4.1 Test piece clamp and striker, meeting the requ
21、irements of 4.1.1 to 4.1.3. 4.1.1 The test piece clamp shall be rigid and designed to hold the test piece(s) as cantilever beam(s). Each individual test piece shall be held firmly and securely in the clamp without distortion. A suitable example of a clamp is shown in Figure 1. Key 1 test piece 2 bod
22、y of clamp 3 holding screw 4 test piece holder Figure 1 Example of test piece clamp 4.1.2 The striking edge shall move relative to the test piece(s) along a path normal to the upper surface of the test piece(s) at a linear testing speed of 2,0 m/s 0,2 m/s at impact. The speed shall be maintained wit
23、hin this range for at least 6 mm of travel following the impact. In order to obtain a speed within the specified limits during and after impact, care shall be taken to ensure that the striking energy is sufficient. It has been found that a striking energy of at least 3,0 J per test piece is necessar
24、y. It might, therefore, be necessary to limit the number of test pieces impacted at one time. 6DIN ISO 812:2015-064.1.3 The principal dimensions of the apparatus see Figures 2a) and 2b) shall be as follows: a) the striking edge shall have a radius of 1,6 mm 0,1 mm; b) the clearance between the strik
25、er and the test piece clamp at impact shall be 6,4 mm 0,3 mm; c) the separation between the point of impact of the striking edge and the test piece clamp shall be 8 mm 0,3 mm; d) the clamping length of the test piece clamp shall be 6,8 mm 0,3 mm. NOTE Commercial apparatus is available meeting the re
26、quirements of this International Standard in which the striking edge is rotated by a motor, or travels in a straight line under the action of a solenoid, gravity or a spring. A method for the speed calibration of a solenoid-actuated low-temperature impact tester is given in Annex A. Dimensions in mi
27、llimetres a) Straight-line motion b) Rotational motion Key 1 test piece 2 striker 3 test piece clamp 4 locus described by point on striker closest to test piece clamp 5 locus described by impact point on striker Figure 2 Test piece clamp and striker 4.2 Heat-transfer medium, liquid or gaseous, which
28、 remains fluid at the test temperature and which does not appreciably affect the material being tested, as prescribed in ISO 23529. Gases can be employed as the heat-transfer medium provided the design of the apparatus is such that results obtained using them will duplicate those obtained with liqui
29、ds. The following fluids have been used satisfactorily: a) for temperatures down to 60 C, silicone fluids of kinematic viscosity of about 5 mm2/s at ambient temperature, which are usually suitable owing to their chemical inertness towards rubbers, their non-flammability and their non-toxicity; b) fo
30、r temperatures down to 73 C, ethanol; c) for temperatures down to 120 C, methylcyclohexane cooled by liquid nitrogen (found to be satisfactory with the use of suitable apparatus). 7DIN ISO 812:2015-064.3 Temperature-measuring device, capable of measuring the temperature to within 0,5 C over the whol
31、e range of temperatures over which the apparatus is to be used. The temperature sensor shall be positioned near the test pieces. 4.4 Temperature control, capable of maintaining the temperature of the heat-transfer medium to within 1 C. 4.5 Container for the heat-transfer medium: A bath for a liquid
32、medium or a test chamber for a gaseous medium, with means of heating the heat-transfer medium. 4.6 Means of agitating the heat-transfer medium: A stirrer for liquids, or a fan or blower for gases, which ensures thorough circulation of the heat-transfer medium. It is important that the stirrer also m
33、oves the liquid vertically to ensure a uniform temperature in the liquid. 4.7 Stopwatch or other timing device, calibrated in seconds. 5 Calibration The test apparatus shall be calibrated in accordance with the schedule given in Annex B. 6 Test pieces Test pieces shall be either type A: a strip 26 m
34、m to 40 mm long, 6 mm 1 mm wide and 2,0 mm 0,2 mm thick; or type B: a test piece 2,0 mm 0,2 mm thick and of the shape and dimensions given in Figure 3. Test pieces shall be prepared in accordance with ISO 23529. They shall normally be punched from sheet using a suitable sharp die. Alternatively, typ
35、e A test pieces can be prepared using sharp, parallel double-bladed cutters, in a single stroke. The strip so formed is then cut to the correct length. Dimensions in millimetres Figure 3 Type B test piece 7 Time interval between manufacture and testing Unless otherwise specified, the time interval b
36、etween the date the material was formed and testing shall be in accordance with ISO 23529. 8DIN ISO 812:2015-068 Procedure 8.1 Procedure A (determination of brittleness temperature) 8.1.1 Bring the bath or test chamber to a temperature below the expected lowest temperature of non-failure. In the cas
37、e of a liquid heat-transfer medium, place sufficient liquid in the bath to ensure approximately 25 mm depth or more of the liquid over the test piece(s). Pre-cool the test piece clamp by immersing it in the cooled bath or test chamber. 8.1.2 Quickly mount the test piece(s) in the test piece clamp an
38、d immerse them for 5 min at the test temperature when using a liquid medium or for 10 min when using a gaseous medium (see also ISO 23529). NOTE 1 For very soft materials, it might be necessary to use a device to support the test piece horizontally until just before the striker is released. The free
39、 length of the test piece(s) shall be greater than 19 mm. Test five type A or type B test pieces. If the available striking energy has the minimum value specified in 4.1.2, they may all be tested at the same time. Proper tightening of the clamp is of the utmost importance. The clamp shall be tighten
40、ed so that each test piece is held with approximately the same clamping torque. NOTE 2 It has been reported that the temperature at which a test piece fails might be affected by the clamping torque. Clamping to a torque of 0,15 Nm to 0,25 Nm is suggested. 8.1.3 After immersion for the specified time
41、 at the test temperature, record the temperature and deliver a single impact blow to the test piece(s). 8.1.4 Remove the test pieces from the test piece clamp and allow them to reach standard laboratory temperature. Examine each test piece to determine whether or not it has failed. Failure is define
42、d as any crack, fissure or hole visible to the naked eye, or complete separation into two or more pieces. Where a test piece has not completely separated, bend it to an angle of 90 in the same direction as the bend caused by the impact. Then examine it for cracks at the bend. 8.1.5 Repeat the test a
43、t each of a series of successively higher temperatures 10 C apart, using a new set of test pieces at each temperature, until no failure is obtained. Then decrease the temperature to the highest value at which a failure was observed and carry out tests at temperatures increasing at 2 C intervals to d
44、etermine the temperature at which no failure is observed. Record this as the brittleness temperature. If crystallization or time-dependent effects of plasticizers are to be studied, longer conditioning periods in a gaseous medium may be used. 8.2 Procedure B (determination of 50 % brittleness temper
45、ature) 8.2.1 Carry out the procedure described in 8.1.1 to 8.1.4, except that the starting temperature is that at which 50 % failure is expected. 8.2.2 If all of the test pieces fail at the starting temperature, increase the temperature by 10 C and repeat the test. If none of the test pieces fail at
46、 the starting temperature, decrease the temperature by 10 C and repeat the test. Increase or decrease the temperature in increments of 2 C and repeat the test until the lowest temperature at which none of the test pieces fails and the highest temperature at which all of the test pieces fail is deter
47、mined. Record the number of failures at each temperature. Use a new set of test pieces at each temperature. Determine the 50 % brittleness temperature by calculation using the equation in 8.2.3 or by the graphical method described in 8.2.4. 9DIN ISO 812:2015-068.2.3 Calculation: From the number of f
48、ailures at each temperature, calculate the percentage of failures at each temperature to determine the 50 % brittleness temperature from the following equation: bh1100 2STT T where Tbis the 50 % brittleness temperature (C); This the highest temperature at which all test pieces fail (C); T is the int
49、erval between the test temperatures (C); S is the total of the percentages of failures at each temperature, from the temperature at which no test piece fails to the temperature at which they all fail, Th(%). 8.2.4 Graphical method: From the number of failures at each temperature, calculate the percentage of failures at each temperature. Next, using normal probability paper as shown in Figure 4, plot these percentag
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1