INTERNATIONAL ISO STANDARD 3146 Third edition 2000-06-01, Plastics — Determination of melting behaviour (melting temperature or melting range) of semi-crystalli capillary tube and pola methods polymers by g-microscope Plastiques — Détermination du comportement a la fusion (température de fusion ou plage de températures de fusion) des polyméres semi-cristalins par méthodes du tube capillare et du microscope polarisant Reference number 1S0 3146:2000(E) © 180 2000ISO 3146:2000(E) PDF disclaimer ‘This POF file may contain embedded typelaces. In accordance with Adobe's lensing policy, this ile may be printa or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed onthe computer performing the editing. In downloading ths fl, Parties accept therain the responsibilty of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no lability in his area ‘Adobe is a trademark of Adobe Systems Incorporated. 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Uniess otherwise speciied, no part ofthis publication may be reproduced or tized in any frm or by any means, elee- tronic or mechanical, ineluding photocopying and mierofim, without permission in wring from ether ISO atthe adress below or ISO's mer ber body inthe country of the requaster. 1S0 copyright otico Case postale 56 » CH-1211 Geneva 20 Tol. +41 2274900 11 Fax +41 22 7341079 E-mall copyright@iso.ch Wed woraso.ch Printed in Switzeriand © 180 2000 ~ Alrights reservedISO 3146:2000(E) Contents Page Scope Normative reference Terms and definitions Method A — Capillary tube Method B — Polarizing microscope anone © 1SO 2000 ~All :ights reserved iiISO 3146:2000(E) Foreword ISO (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 ISO technical com- mmittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liai- ‘son with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3 Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International 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 International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 3146 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-chemical properties. This third edition cancels and replaces the second edition (ISO 3146:1985), which has been technically revised. iv © 180 2000 ~ Alrights reservedISO 3146:2000(E) Introduction The melting behaviour of a crystalline or semi-crystalline polymer is a structure-sensitive property. In polymers, a sharp metting point, such as is observed for low molecular mass substances, usually does not occur; instead a melting temperature range is observed on heating, from the first change of shape of the solid particles to the transformation into a highly viscous or viscoelastic liquid, with accompanying disappearance of the crystalline phase. The melting range depends upon a number of parameters, such as molecular mass, molecular mass distribu- tion, per cent crystallinity, and thermodynamic properties. It may also depend on the previous thermal history of the specimens. The lower or upper limit of the melting range, or its average value, is sometimes conventionally referred to as the “melting temperature”. © 1SO 2000 ~All :ights reserved vINTERNATIONAL STANDARD ISO 3146:2000(E) Plastics — Determination of melting behaviour (mel temperature or melting range) of semi-crystalline polymers by capillary tube and polarizing-microscope methods 1 Scope This International Standard specifies two methods for evaluating the melting behaviour of semi-crystalline polymers. Melting temperatures determined by the different methods usually differ by several kelvins for the reasons explained in the introduction. Method A: Capillary tube This method is based on the changes in shape of the polymer. itis applicable to all semi-crystalline polymers and their compounds. NOTE 1 Method A may also be useful forthe evaluation ofthe softening of non-crystalline solids. Method B: Polarizing microscope This method is based on changes in the optical properties of the polymer. It is applicable to polymers containing a birefringent crystalline phase. It may not be suitable for plastics compounds containing pigments andior other addi- tives which could interfere with the birefringence of the polymeric crystalline zone. NOTE 2 Another method applicable to semni-crystalline polymers is described in ISO 11357-8:1999, Plastics — Differential scan- hing calorimetry (SC) — Part 3: Determination of temperature and enthalpy of melting and erystalization. 2 Normative reference The following normative document contains provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publica~ tions do not apply. However, parties to agreements based on this International Standard are encouraged to investi- gate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards, ISO 291, Plastics — Standard atmospheres for conditioning and testing. 3. Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 34 semi-crystalline polymer polymer containing both crystalline and amorphous phases which may be present in varying proportions © 1SO 2000 ~All :ights reserved 1ISO 3146:2000(E) 32 melting range the temperature range over which crystalline or semi-crystalline polymers lose their crystalline characteristics or par- ticulate shape when heated NOTE Thi ting temperatures” determined by methods A and B are defined in 4.1 and 5.1 4 Method A— Capillary tube 44 Principle ‘A test sample is heated at a controlled rate, and the temperature of the sample measured at the first visible change in shape and again at the disappearance of the last remnants of the crystalline phase. ‘The first temperature is taken as the melting temperature of the sample, while the range between the two tempera- tures describes its melting range. NOTE This method may be used for non-crystalline materials where required by the relevant specifications or by agreement be- tween the interested parties. 4.2. Apparatus (see Figure 1) 4.2.1 Melting apparatus, consisting of the following items: a) Cylindrical metal block, the upper part of which is hollow and forms a chamber, 'b) Metal plug, with two or more holes, allowing a thermometer and one or more capillary tubes to be mounted in the metal block. ©) Heating system for the metal block, for example an electrical resistance enclosed in the block. 4d) Rheostat for regulation of the power input, if electrical heating is used. ) Four windows of heat-resistant glass on the lateral walls of the chamber, diametrically disposed at right angles to each other. In front of one of these windows an eyepiece is mounted for observing the capillary tube. The other three windows are used for illuminating the inside of the enclosure by means of lamps. NOTE Other suitable types of melting apparatus may be used, provided that they give the same results. 422 Cay lary tube, of heat-resistant glass, closed at one end, NOTE The maximum external diameter should preferably be 1,5 mm. 4.2.3 Calibrated thermometer, graduated in divisions of 0,1 °C. The thermometer bulb shall be positioned in such ‘a way that heat dispersion in the apparatus is not impeded. NOTE Other suitable temperature-measuring devices may be used. 4.3 Test samples 4.3.1, General The test samples used shall be representative of the material to be tested. 2 © 180 2000 ~ Alrights reservedISO 3146:2000(E) Metal heating block Lamp Metal plug Thermometer Capillary Eyepiece Electrical resistance Figure 1 — Apparatus for method A 4.3.2. Characteristics Powder of particle size up to 100 um or cut pieces of film of thickness 10 jum to 20 jum should preferably be used. ‘Comparison tests shall be carried out on test samples of the same or similar particle size, or of similar thickness in the case of layers or films. 4.3.3 Conditioning It not otherwise specified or agreed between the interested parties, the test sample shall be conditioned at 28°C + 2°C anda relative humidity of (50 + 5) % for h in accordance with ISO 291 prior to the measurement. 4.4 Procedure 4.4.1 Calibration Periodically calibrate the thermometer with reagent grade or certified chemicals over the temperature range used for the test. Chemicals recommended for calibration purposes are listed in Table 1 © 1SO 2000 ~All :ights reserved 3ISO 3146:2000(E) Table 1 — Calibration standards ‘Chemical Melting tomperature® (0) i-Menthol 425) [azobenzene 690 &-Hydroxyquinoine 755 Naphthalene 802 [Benzene 96.0 Acetanitide 1136 Benzoic acid Ta17, Phenacetin (pacetophenetidide) 136.0 Adipic acid 1515 ingiom 156.4 Suifanilamide 165.7 Hiyaroquinone 1708 Succinic acid 1895 2-Ghloroanthraquinone 2080 Anthracene 217.0 [Saccharin 2294 Tin 231.9 Hing) ehioride 247.0 Phenolphihalein 2615 The temperatures indicated refer to theoretically pure chemicals; the value of the sua rein poh tore sander materiale uod shoud be cored byte sup 4.4.2. Determination 4.4.2.1. Insert the thermometer (4.2.3) and the capillary tube (4.2.2) containing the test sample into the metal block [4.2.1 a)] and begin heating. Adjust the controller [4.2.1 d)] to heat the specimen gradually (at a rate not higher than 10 °C/min) to a temperature that is about 20 °C lower than the expected melting temperature. When the temperature of the test sample is about 20 °C below the expected melting temperature, adjust the rate of temperature increase to 2°Cimin + 0,5 °C/min. Record the temperature at which the test sample begins to change shape. Continue heating at the same rate. Record the temperature at which the last remnants of the crystalline phase disap- pear. 4.4.2.2. Repeat the operations specified in 4.4.2.1 with a second test sample. If the two results obtained by the same ‘operator on the same sample differ by more than 8 °C, repeat the procedure on two new test samples. 45 Test report ‘The test report shall include the following information: a) a reference to this International Standard; b) the method used (method A); ©) all details necessary for complete identification of the material tested; 4) the shape and size (or mass) of the test samples; ) the previous thermal history of the test samples; f) the conditioning procedure used; 4 © 180 2000 ~ Alrights reservedISO 3146:2000(E) 9) the exact heating rate used; h) the temperatures, in degrees Celsius, of two successive determinations, and their arithmetic mean for the tem- perature at which the specimen begins to change shape and for the temperature at which the last remnants of crystalline phase disappear; i) any operational details not specified in this International Standard or regarded as optional, as well as any inci- dents liable to have affected the results. 5 Method B — Polarizing microscope 5.1. Principle A tost sample positioned between the disc polarizer and the cap analyser of a microscope is heated at a controlled rate. ‘The temperature at which the crystalline phase of the polymer loses its optical anisotropy is measured as detected by the disappearance of birefringence and reported as the melting temperature. 5.2. Apparatus 5.2.1. Microscope, with disk polarizer and cap analyser, or a polarizing microscope with built-in analyser, with magnification from x 50 to x 100. 5.2.2 Micro hot-stage, consisting of an insulated metal block that can be mounted slightly above the microscope stage. This block shall be a) provided with a hole for the passage of light; b) electrically heated, with adequate controls for adjustment of heating and cooling rates; ©) so constructed to provide a chamber with a heat battle and a glass cover, for carrying out measurements in an inert atmosphere; 4) provided with a hole for the insertion of a temperature-measuring device near the light hole a). 5.2.3 Thermometers, calibrated, or equivalent temperature-measuring devices, for the test temperature ranges. 5.3 Test samples 5.3.1 Powdered mater Place a 2 mg to 3mg portion of the powder sample (particle size < 100 im) on a clean glass slide and cover with a cover glass. NOTE Depending on the effective heating rate, the temperature and time at which the test sample is held in the molten state and the effective cooling rate, the results of subsequent melting may difer. Heat the test sample assembly (the test sample, the slide and the cover) on a hot-plate to slightly above the metting temperature of the polymer. By applying a slight pressure to the cover glass, form a thin film of thickness 0,01 mm to 0,04 mm and allow the assembly to cool slowly by switching off the hot-plate. 5.3.2 Moulded or pelleted mat. Using a microtome, cut a flm of approximately 0,02 mm thickness from the sample, place it on a clean slide and cover with a cover glass. Heat and melt it as specified in 5.3.1. © 1SO 2000 ~All :ights reserved 5ISO 3146:2000(E) 5.3.3 Film or sheet materials Cut out a 2 mg to 3 mg portion of the film or sheet sample, place it on a clean slide, cover with a cover glass and pro- ceed as specified in 5.3.1. The preliminary melting of the test sample between slide and cover has the advantage of destroying any birefrin- gence due to orientation or internal stresses, and also reduces the danger of oxidation during the test. The need for an inert gas stream — as specified in 5.2.2 c) —is limited to very special cases. The reproducibility of the measure- ments is also increased. However, if, by agreement between interested parties, the determination is carried out directly on the powder or piece of film or sheet without preliminary melting, this deviation shall be stated in the test report. 5.3.4 Conditioning See 4.3.3. NOTE The effects of conditioning may be erased or changed by preliminary melting ofthe test sample on the hot-plate. 5.4 Procedure 5.4.1. Calibration See 4.4.1. 5.4.2 Determination Place the test sample assembly (see 6.8.1, §.8.2 or 5.3.3) on the micro hot-stage (6.2.2). Adjust the light source to maximum light intensity. Focus the microscope (6.2.1). Rotate the analyser to obtain a dark field; the crystalline material will appear bright on the dark field. Adjust the con- troller to heat the stage gradually (at a rate not higher than 10 °Cimin) to a temperature that is lower than the melting temperature Tm, as determined approximately by a preliminary test, by one of the following amounts: 10°C for Tm < 150°C 15°C for 150°C < Ty < 200°C 20°C for Im > 200°C ‘Adjust the temperature controller so that the temperature rises at a rate of 1 °C/min to 2 °C/min. Observe the temperature at which birefringence disappears, leaving a totally dark field. Record this temperature as the melting temperature of the test sample. ‘Turn off the power to the micro hot-stage and remove the glass cover, heat baffle and test sample slide. Repeat the procedure with another test sample. If the two results obtained by the same operator on the same sample differ by more than 1 °C, repeat the procedure on two new test samples. 5.5 Preci According to the results of round robins, the repeatability is 2°C. Insutficient data are available to determine the re- producibilty 6 © 180 2000 ~ Alrights reservedISO 3146:2000(E) 5.6 Test report The test report shall include the following information: a) a reference to this International Standard; b) the method used (method B); ©) all details necessary for complete identification of the material tested; ) the shape and size (or mass) of the test samples; ©) the previous thermal history of the test samples; ) the conditioning procedure used; 9) a description of the preliminary heating on the slide, if applicable; h) if applicable, the fact that an inert gas was used and, if so, the type of gas; i) the exact heating rate used; j) the temperatures, in degrees Celsius, of two successive determinations and their arithmetic mean; )_any operational details not specified in this International Standard or regarded as optional, as well as any inci- dents liable to have affected the results. © 1SO 2000 ~All :ights reserved 7ISO 3146:2000(E) ICS 83.080.01 Price based on 7 pages © 180 2000 ~All ights reserved