1、BRITISH STANDARD BS 2782-7: Method 740B: 1996 ISO 1147:1995 Methods of testing Plastics Part 7: Rheological properties Method 740B: Polymer dispersions and synthetic rubber latices Freeze-thaw cycle stability test ICS 83.040.10; 83.080BS2782-7:Method740B:1996 This British Standard, having been prepa
2、red under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15 July 1996 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PRI/21 Draft for comment 94/342459 DC I
3、SBN 0 580 25989 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/21, Testing of plastics, upon which the following bodies were represented: British Apparel and Textile Confederation British Plastics Federation Depart
4、ment of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) Electrical and Electronic Insulation Association GAMBICA (BEAMA Ltd.) Institute of Materials Ministry of Defence Packaging and Industrial Films Association PIRA International RAP
5、RA Technology Ltd. Royal Society of Chemistry Amendments issued since publication Amd. No. Date CommentsBS2782-7:Method740B:1996 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Apparatus 1 5 Procedure 1 6 E
6、xpression of results 2 7 Test report 2 List of references Inside back coverBS2782-7:Method740B:1996 ii BSI 11-1999 National foreword This Method of BS 2782-7 has been prepared by Technical Committee PRI/21 and is identical with ISO1147:1995 Plastics/rubber Polymer dispersions and synthetic rubber la
7、tices Freeze-thaw cycle stability test, published by the International Organization for Standardization (ISO). The Technical Committee has reviewed the provisions of the latest draft of ISO12000 1)to which normative reference is made in the text and has decided that they are acceptable for use in co
8、njunction with this standard. NOTEInternational and European Standards as well as overseas standards are available from Customer Services, BSI,389 Chiswick High Road, London, W44AL. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards
9、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, pagesi andii, pages1 and2, an inside back cover and a back cover. This standard
10、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. Cross-references Publication referred to Corresponding British Standard ISO 2555:1989 BS 2782 Methods of testing plastics Part 7 Rheological proper
11、ties Method 730C:1992 Determination of apparent viscosity of resins by the Brookfield Test method (Identical) ISO 3219:1993 BS EN ISO 3219:1995 Plastics. Polymers/resins in the liquid state or as emulsions or dispersions. Determination of viscosity using a rotational viscometer with defined shear st
12、ate (Identical) 1) It is envisaged that upon publication ISO12000 will be implemented in the UK by the publication ofBS2782-7:Method740A.BS2782-7:Method740B:1996 BSI 11-1999 1 1 Scope This International Standard specifies a procedure for the evaluation of the freeze-thaw cycle stability of polymer d
13、ispersions and synthetic rubber latices. It does not apply to natural rubber latex. The test has no significance if the sample does not freeze under the test conditions. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of
14、this InternationalStandard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicat
15、ed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 2555:1989, Plastics Resins in the liquid state or as emulsions or dispersions Determination of apparent viscosity by the Brookfield Test Method. ISO 3219:1993, Plastics Polymers/resins in the liquid s
16、tate or as emulsions or dispersions Determination of viscosity using a rotational viscometer with defined shear rate. ISO 12000:, Polymer dispersions and rubber latices (natural and synthetic) Definitions and review of test methods 2) . 3 Principle The viscosity of a sample of the polymer dispersion
17、 under test is measured. The sample is placed in a test chamber for16h at a temperature of 5 C,10 C or20 C, then held for8h at23 C. Finally, the appearance of the polymer dispersion is checked. If coagulation has occurred, the test is considered to be completed. In cases of doubt, the viscosity is r
18、emeasured. If it has changed by more than the manufacturers specification limit, then the test is considered to be completed. If it has not changed by more than the manufacturers specification limit, the cycle is repeated, i.e.the sample is stored at the selected temperature for another16h and then
19、held at23 C for8h, up to a maximum number of three cycles, the viscosity of the dispersion being remeasured after each cycle. NOTE 1The freeze temperature selected will depend on the chemical nature of the polymer dispersion and the temperature to which it is exposed in service. If required, prelimi
20、nary tests may be carried out to determine the appropriate test temperature. 4 Apparatus 4.1 Cylindrical container, with a large opening fitted with a stopper, and with the following dimensions: height: 100 mm inside diameter: 40 mm wall thickness: 2 mm NOTE 2It is important not to deviate from thes
21、e dimensions as the results are sensitive to the size of the container. At freeze temperatures of 5 C or 10 C, the container may be made of polyethylene; at lower freeze temperatures a stainless-steel container shall be used. 4.2 Test chamber, comprising a suitable cabinet, room or enclosure large e
22、nough to contain the samples to be tested, allowing at least25mm of air space between the sides of adjacent containers and capable of being maintained at temperatures of 5 C 0,5 C,10 C 0,5 C and20 C 1 C. 4.3 Thermometer or thermocouple, capable of measuring the temperature inside the test chamber to
23、 the nearest0,5 C. 4.4 Viscometer, as specified in ISO3219 or ISO2555, as appropriate, to determine the viscosity of the polymer dispersion. 5 Procedure NOTE 3By agreement between the interested parties, a property other than viscosity may be used for the test. 5.1 Put 100g 1g of test sample into th
24、e cylindrical container (4.1). Measure the viscosity of the sample at23 C in accordance with ISO3219 or ISO2555, and note the result. 5.2 Stopper the container and place it for16h in the test chamber (4.2) set at the selected freeze temperature kept constant to within 0,5 C. 5.3 Remove the container
25、 from the test chamber and let it thaw at23 C for8h. 5.4 Check the condition of the dispersion by inserting a glass rod. If there is complete coagulation or the formation of clots of coagulum that cannot be dispersed by stirring, regard the test as completed and record the appearance of the dispersi
26、on. 2) To be published.BS2782-7:Method740B:1996 2 BSI 11-1999 If this check is not conclusive, measure the viscosity of the sample at23 C as described in5.1. If the viscosity has changed from its initial value by more than the manufacturers specification limit, regard the test as completed. If not,
27、subject the dispersion to a further complete freeze-thaw cycle. 5.5 Homogenize the sample if necessary, e.g.if the sample shows a water layer on the surface or has thickened. 5.6 If necessary, continue the test until three freeze-thaw cycles have been completed, remeasuring the viscosity of the samp
28、le at23 C after each cycle. 5.7 Note the freeze temperature used, the appearance of the sample after each cycle, the number of cycles completed without formation of visible, indispersable coagulum or clots (or without a change in viscosity of more than the manufacturers specification limit), the ini
29、tial viscosity and the final viscosity. 5.8 In the special case of dispersions in which the polymer tends to crystallize for example poly(vinylidene chloride), an additional check may be carried out by verifying whether the aptitude for film formation is still good after the freeze-thaw cycles. 6 Ex
30、pression of results The freeze-thaw stability of the polymer dispersion at a selected freeze temperature is expressed as the number of cycles endured without the formation of visible and indispersable coagulum or clots or without a change in viscosity exceeding the manufacturers specification limit.
31、 NOTE 4Failure to meet either of these requirements does not necessarily mean that the polymer dispersion will be unsuitable for a particular application. 7 Test report The test report shall include the following particulars: a) a reference to this International Standard; b) all details necessary fo
32、r complete identification of the product tested; c) the freeze temperature used; d) the freeze-thaw stability at this freeze temperature, expressed as the number of cycles endured without coagulation; e) the method used to measure the viscosity; f) the initial and final viscosities of the polymer di
33、spersion; g) details of any modification to the procedure described and details of any circumstances which may have affected the results; h) if the aptitude for film formation was verified, the method employed and the result obtained; i) the date of the test.BS2782-7:Method740B:1996 BSI 11-1999 List
34、 of references See national foreword.BS 2782-7: Method 740B: 1996 ISO1147:1995 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the internatio
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