1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58method Part 1: Measurement of the processing temperatureICS 23.040.20Rigid PVC pipes Differential s
2、canning calorimetry (DSC) BRITISH STANDARDBS ISO 18373-1:2007BS ISO 18373-1:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 September 2007 BSI 2007ISBN 978 0 580 56391 1Amendments issued since publicationAmd. No. Date CommentsComplianc
3、e with a British Standard cannot confer immunity from legal obligations. National forewordThis British Standard is the UK implementation of ISO 18373-1:2007.The UK participation in its preparation was entrusted by Technical Committee PRI/88, Plastics piping systems, to Subcommittee PRI/88/4, Test me
4、thods.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.INTERNATIONALSTANDARDISO18373-1First edition2007-07-15Ref
5、erence numberISO 18373-1:2007(E)Rigid PVC pipes Differential scanning calorimetry (DSC) method Part 1:Measurement of the processing temperatureTubes rigides en PVC Mthode utilisant la calorimtrie diffrentielle balayage Partie 1: Mesurage de la temprature de procdBS ISO 18373-1:2007iiiiiForewordISO (
6、the International Organization for Standardization) is a worldwide federation of national standards bodies(ISO member bodies). The work of preparing International Standards is normally carried out through ISOtechnical committees. Each member body interested in a subject for which a technical committ
7、ee has beenestablished has the right to be represented on that committee. International organizations, governmental andnon-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnical Commission (IEC) on all matters of electrotechnica
8、l standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies
9、 for voting. Publication as anInternational Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patentrights. ISO shall not be held responsible for identifying any or al
10、l such patent rights.ISO 18373-1 was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for thetransport of fluids, Subcommittee SC 5, General properties of pipes, fittings and valves of plastic materials andtheir accessories - Test methods and basic specifications.ISO 1
11、8373 consists of the following parts, under the general title Rigid PVC pipes Differential scanningcalorimetry (DSC) method: Part 1: Measurement of the processing temperature Part 2: Measurement of the enthalpy of fusion of crystallitesBS ISO 18373-1:2007ivIntroductionStudies have been undertaken at
12、 the international level to determine a method of measuring the B-onset ormaximum processing temperature used during the production of rigid PVC pipes. These studies havedemonstrated that a test using differential scanning calorimetry (DSC) fulfils these requirements.The method involves taking small
13、 samples from the pipe wall and heating these in a differential scanningcalorimeter. Small endotherms are used to detect the thermal history of the samples and the B-onset ormaximum processing temperature is derived from these data.The technique requires a good understanding of DSC instruments and t
14、echniques, particularly in relation toPVC. It is important that newcomers to the technique familiarize themselves with both the instrumentation andmethod prior to undertaking reportable tests.It is intended that individual product standards will specify the requirements for B-onset or maximum proces
15、singtemperature.The method can also be suitable for other types of extruded rigid PVC products, but different sampling protocolsmight be required.BS ISO 18373-1:20071Rigid PVC pipes Differential scanning calorimetry (DSC) method Part 1:Measurement of the processing temperature1ScopeThis part of ISO
16、18373 specifies a method for the determination of the processing temperature of rigid PVCpipe samples. The method is based on the measurement of the thermal history using differential scanningcalorimetry (DSC) and is suitable for all types of rigid PVC pipes.2 Terms and definitionsFor the purposes o
17、f this document, the following terms and definitions apply.2.1 baseline tiltingadjustment of the angle of the baseline to bring it to the horizontal2.2 curve magnificationmagnification of the differential scanning calorimetry (DSC) curve around A-onset and B-onset temperature(“zooming”)2.3 A-onsetin
18、dication of first crystallite melting2.4 B-onsetindication of maximum processing temperature ( )2.5 instrumental baselinemeasurement with empty sample pan, i.e. background subtraction2.6 position of samplelocation in the product from where the sample was taken2.7 purge gasgas used to ensure an inert
19、 environment2.8 repeat samplessamples from the same positionTpBS ISO 18373-1:200723PrincipleDSC is a well-established method for testing the melt temperature in PVC products (see References 1and 2).The benefits with this test are that an accurate assessment can be made of the processing temperature,
20、 as wellas the possibility of finding variations in the processing temperature in local areas of the product, due to the factthat only a small size of sample is required for the test. This enables the operator to cut samples from differentlocations around the pipe circumference. Thus, temperature va
21、riations in the pipe wall can be examined.The characteristic B-onset temperature occurs because crystallites with melting points at or above themaximum processing temperature ( ) will be annealed, thus slightly raising their melting point. Crystallites thatdo melt at will recrystallize on cooling an
22、d therefore will have melting points below . Thus, there are veryfew crystallites with melting temperatures in the immediate vicinity of .4 Apparatus4.1 DSC instrument, and associated software, calibrated.Calibration should be carried out using at least two different metals. An instrumental baseline
23、 must be obtainedwith an empty sample pan and reference pan in place, and with temperature settings and purge gas identical tothe settings to be used for the sample analysis.4.2 Aluminium sample pans.4.3 Inert purge gas (e.g. N2, Ar, etc.), of at least industrial quality.4.4 Analytical balance, with
24、 an accuracy to within .4.5 Slow-speed saw (see Reference 3), knife, or any other device introducing neither heat nor stress intothe sample as it is cut.5 Preparation of the test pieces and the test5.1 Take at least four samples at the , , and positions, respectively, around the pipecircumference, w
25、ith all the samples being taken from the centre of the pipe wall.NOTE The samples are taken from the centre of the pipe wall because the processing temperature at the centre of the pipewall is often lower than that close to the inner and outer surfaces, where additional shear occurs.CAUTION Taking s
26、amples from the locus of a spider line can lead to an increase in the spread ofresults.5.2 Prepare the test pieces having a mass of in a way that maximizes the contact surfacebetween the pan and the test piece.NOTE Maximizing the contact surface between the pan and the test piece reduces the resista
27、nce to heat flow through theDSC temperature sensors and results in maximum peak sharpness and resolution.5.3 The best test piece shapes for optimum performance are thin disks placed on the bottom of the pan. Testpieces may be conveniently prepared by cutting out sections with a slow-speed saw or wit
28、h a razor or knife(4.5). A hole punch or cork borer may be used if the sample is very thin.TpTpTpTp0,01 mg090180270(20 10) mgBS ISO 18373-1:200736 Procedure6.1 Ensure that the scanning device is calibrated.6.2 Encapsulate the test piece in an aluminium pan with cover.6.3 It is important that the tes
29、t piece does not move in the pan during the measurement. The most commonmethod to immobilize the test piece is to crimp the pan cover in place with a crimper. This yields a tightly, but nothermetically, sealed pan without movement of the test piece in the pan during the measurement. Other methodsof
30、pan closure that immobilize the test piece may be used.6.4 Using the following test parameters, perform and register the scan:a) start temperature: ;b) end temperature: ;c) heating rate: ;d) purge gas (4.3): .7 Expression of resultsIf necessary, magnify the relevant part of the curve using the zoomi
31、ng feature of the DSC instrument. Determinethe B-onset by taking tangents to the DSC curve at the points of maximum slope just before and just after thispoint of inflection in the curve, as shown in Figure 1.NOTE 1 A typical curve consists of two endotherms between approximately and approximately wh
32、ere theB-onset corresponds very closely to the maximum processing temperature, . The change in energy levels is usually quitesmall. See Figure 2 for an example.If the individual results from three consecutive tests on samples taken from the same location (i.e. the sameangular location) within a pipe
33、 differ by more than , then further tests shall be made and/or the instrumentre-calibrated.NOTE 2 If the glass transition values, (typically at to ), do not vary by this amount, then the differencesreflect real differences in the sample.Uneven or irregular scan data shall be discarded.Possible sourc
34、es of error are given in Annex C.The correlation between B-onset temperature and time to stress rupture is given in Annex D.NOTE 3 The appearance of DSC curves can differ depending upon whether the curve is displayed as “exo up” (seeFigures 1 and 2) or “exo down”. The latter type produce “inverted”
35、curves compared with Figures 1 and 2. Examples of thedifferent types of presentation are shown in Annex A.NOTE 4 The presence of some additives can also be detected by DSC and so extra peaks can appear in the DSC curvesas a result. Examples of these are shown in Annex B.(35 15)C225C(20 1)C/min(20 5)
36、C/min100C 200CTp3CTg 70C 80CBS ISO 18373-1:20074KeyX temperature ( )Y heat flow (mW)1 extrapolated peak at Figure 1 DSC result curve after zoomingKeyX temperature ( )Y heat flow (mW)Figure 2 Typical DSC curve from a PVC pipeC188,36CCBS ISO 18373-1:200758 Test reportThe test report shall contain the
37、following information:a) reference to this part of ISO 18373;b) sample reference number (e.g. production code number of the pipe);c) location from where the samples were taken (e.g. , , , around the circumference of thepipe);d) mean and standard deviation of B-onset temperature;e) number of repeat s
38、amples tested;f) minimum value of B-onset measured in any single scan;g) any factors that could have affected the results, such as any incidents, test interruptions or any operatingdetails not specified in this standard;h) date(s) of test.090180270BS ISO 18373-1:20076Annex A(informative)Possible pre
39、sentations of DSC curvesFigure A.1 shows a typical curve from an “exo down” instrument, and Figure A.2 shows a typical curve from an“exo up” instrument.KeyX temperature ( )Y heat flow (mW)1 extrapolated peak at Figure A.1 Typical curve from an “exo down” instrumentC189,40CBS ISO 18373-1:20077KeyX te
40、mperature ( )Y heat flow (mW)1 extrapolated peak at Figure A.2 Typical curve from an “exo up” instrumentC190,91CBS ISO 18373-1:20078Annex B(informative)Example of spurious peaks due to the presence of additivesFigure B.1 shows a DSC curve with a spurious peak at approximately , due to the presence o
41、f oxidizedPE wax used as a lubricant in the pipe formulation.KeyX temperature ( )Y heat flow (mW)Figure B.1 Example of a spurious peak130CCBS ISO 18373-1:20079Annex C(informative)Possible sources of errorPotential sources of error include the following:a) sample inhomogeneity due to the partially cr
42、ystalline nature of rigid PVC;b) movement of the sample in the pan;c) internal stresses in the material, which are released when the sample is heated and can mask or interferewith the result curve;d) other thermal events at temperatures close to B-onset due to the presence in the pipe of additives,
43、blowingagents, etc., which go through thermal events such as evaporation, decomposition and/or melting attemperatures close to B-onset;e) frictional heat from sample preparation, e.g. from the use of a high-speed saw.BS ISO 18373-1:200710Annex D(informative)Correlation between B-onset temperature an
44、d time to stress ruptureFigure D.1 shows the test result of rigid PVC pipes subjected to pressure at according toISO 1167-14.KeyX B-onset temperature ( )Y time to stress rupture at (h)1 standard deviation2 average time to stress ruptureFigure D.1 B-onset temperature and time to stress rupture14 MPa
45、60CC60CBS ISO 18373-1:200711Bibliography1 GILBERT, M., HEMSLEY, D.A. and MIADONYE, A. Assessment of fusion in PVC compounds. Plastics andRubber Processing and Applications, 3 (1983) pp. 343-3512 FILLOT, L.A., GAUTHIER, C. and HAJJI, P. DSC Technique: a powerful tool to characterise PVC gelation.Proc
46、. of 9th International PVC Conference Brighton 2005, Brighton, April 2005, pp. 425-4373 VANSPEYBROECK, P. and DEWILDE, A. Determination of the degree of gelation of PVC-U using a DSC.Annex 1, Proc. Plastics Pipes XII, Baveno, April 20044 ISO 1167-1, Thermoplastics pipes, fittings and assemblies for
47、the conveyance of fluids Determinationof the resistance to internal pressure Part 1: General methodBS ISO 18373-1:2007BS ISO BSI389 Chiswick High RoadLondonW4 4AL18373-1:2007BSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents
48、 the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.RevisionsBritish Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions.It is the constant aim of BSI to im
49、prove the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0)20 8996 9000. Fax: +44 (0)20 8996 7400.BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions
