1、Designation: D5930 16D5930 17Standard Test Method forThermal Conductivity of Plastics by Means of a TransientLine-Source Technique1This standard is issued under the fixed designation D5930; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the thermal conductivity of plastics over a temperatur
3、e range from 40 to400C. It is possible to measure the thermal conductivity of materials filled and unfilled thermoplastics, thermosets, and rubbersin the range from 0.08 to 2.0 W/m.K covering thermoplastics, thermosets, and rubbers, filled and reinforced.W/m.K.1.2 The values stated in SI units shall
4、 be regarded as standard.1.3 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of theuser of this standard to establish proper safety and health practices and determine the applicability of regulatory limitations priorto use.NOTE
5、 1There is no known ISO equivalent to this test method.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedb
6、y the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C177 Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate ApparatusC518 Test Method for Steady-State Thermal Trans
7、mission Properties by Means of the Heat Flow Meter ApparatusC1113 Test Method for Thermal Conductivity of Refractories by Hot Wire (Platinum Resistance Thermometer Technique)D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD2717 Test Method for Thermal Conducti
8、vity of LiquidsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE1225 Test Method for Thermal Conductivity of Solids Using the Guarded-Comparative-Longitudinal Heat Flow Technique3. Terminology3.1 DefinitionsTerminology used in this standard is in accordance with Terminology
9、 D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 temperature transient, nthe temperature rise associated with the perturbation of a system, initially at a uniformtemperature. The system does not attain thermal equilibrium during the transient.3.2.2 thermal conductivity, nthe time rate
10、of steady heat flow/unit area through unit thickness of a homogeneous material ina direction perpendicular to the surface induced by a unit temperature difference.3.2.2.1 Discussion1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subc
11、ommittee D20.30 on Thermal Properties.Current edition approved Sept. 1, 2016Aug. 1, 2017. Published September 2016August 2017. Originally approved in 1997. Last previous edition approved in 20092016as D5930 - 09.D5930 - 16. DOI: 10.1520/D5930-16.10.1520/D5930-17.2 For referencedASTM standards, visit
12、 theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard
13、 an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is
14、 to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Where other modes of heat transfer are present in addition to conduction, such as
15、 convection and radiation, this property often isreferred to as the apparent thermal conductivity, app.3.2.2.2 DiscussionThermal conductivity must be associated with the conditions under which it is measured, such as temperature and pressure, as wellas the compositional variation of the material. It
16、 is possible that thermal conductivity will vary with direction and orientation ofthe specimen since some materials are not isotropic with respect to thermal conductivity. In the case of thermoset polymers, it ispossible that thermal conductivity will vary with the extent of cure.3.2.3 thermal diffu
17、sivitya heat-transport property given by the thermal conductivity divided by the thermal mass, which is aproduct of the density and the heat capacity.3.3 Symbols:3.3.1 CProbe constant.3.3.2 Thermal conductivity, W/m.K.3.3.3 QHeat output per unit length, W/m.3.3.4 T2The temperature (K) recorded at ti
18、me t2.3.3.5 T1The temperature (K) recorded at time t1.3.4 Subscript:3.4.1 avaverage.3.4.2 appapparent.3.4.3 refreference.4. Summary of Test Method4.1 Line-Source TechniqueThis is a transient method for determining thermal conductivity (1, 2).3 A line source of heat islocated at the center of the spe
19、cimen being tested. The apparatus is at a constant initial temperature. During the course of themeasurement, a known amount of heat produced by the line-source results in a heat wave propagating radially into the specimen.The rate of heat propagation is related to the thermal diffusivity of the poly
20、mer. The temperature rise of the line-source varieslinearly with the logarithm of time (3). It is possible to use this relationship to directly calculate the thermal conductivity of thesample. There are a number of ways to achieve the line source of heat. In this test method, it is in the form of a
21、probe as describedin 7.2.5. Significance and Use5.1 The relative simplicity of the test method makes it applicable for a wide range of materials (4, 5). The technique is capableof fast measurements, making it possible to take data before the materials suffer thermal degradation. Alternatively, it is
22、 possibleto study the effect of compositional changes such as chemical reaction or aging (6). Short measurement times permit generationof large amounts of data with little effort. The line-source probe and the accompanying test specimen are small in size, makingit possible to subject the sample to a
23、 wide range of test conditions. Because this test method does not contain a numerical precisionand bias statement, it shall not be used as a referee test method in case of dispute.6. Interferences6.1 The line-source method produces results of highest precision with materials where intimate contact w
24、ith the probe has beenestablished, thereby eliminating effects of thermal contact resistance. These materials include viscous fluids and soft solids.6.1.1 Thermal-Contact ResistanceIn the solid state, it is possible that a contact resistance is developed due to the interfacebetween the specimen and
25、the measuring device. Conventional methods attempt to account for this by introducing a conductivepaste between the specimen and the sensor. This reduces, but some effect of contact resistance is still possible. In the line-sourcemethod, contact resistance manifests itself as a nonlinearity in the i
26、nitial portion of the transient (see Fig. 1). The technique hasa method to account for this phenomenon. By extending the time of the measurement, it is possible to progress beyond the regionof thermal-contact resistance, achieving a state where the contact resistance does not contribute to the measu
27、red transient (7). Thisstate typically is achieved after about 10 to 20 s in the measurement. The larger the contact resistance, the greater is this time. Itis, therefore, important to make a sufficiently long measurement to exclude the portion of the transient that shows the effect of thecontact re
28、sistance.The duration of measurement, however, must not be too long, or else the because the possibility of the heat wavestriking a sample boundary exists, thereby violating the theoretical conditionsrequirements of the measurement.3 The boldface numbers in parentheses refer to the list of reference
29、s at the end of this standard.D5930 1726.1.2 Shrinkage Upon SolidificationPlastics tend to shrink significantly upon solidification. This shrinkage is especially so forthe semi-crystalline materials, which experience a significant change in specific volume upon crystallization. The probability exist
30、sthat this crystallization will result in large gaps being developed between the specimen and the sensing device. To account forshrinkage, and possibly permit the line-source probe to move downward to take up the slack a simple compression scheme asdescribed in 9.5 has been used successfully. Steps
31、also must be taken to minimize specimen volume so as to reduce the extent ofshrinkage.6.2 Measurements on in viscid fluids are subject to the development of convection currents, which have been known to affectthe measurement. Because of the transient nature of the measurement, these effects are not
32、as pronounced. They cannot beeliminated, however.6.3 Although the technique is not limited by temperature, at measurements above 500C, a significant amount of heat transferoccurs due to radiation so that it is possible to measure only a app is possible to be measured7. Apparatus7.1 The apparatus con
33、sists of a line-source probe imbedded in a specimen contained in a constant-temperature environment.During the measurement, the line-source probe produces a precise amount of heat. The resulting temperature transient is recorded,preferably, on a computer data-acquisition system, as specified in 7.4.
34、 This transient is analyzed to obtain the thermal conductivity.7.2 Line-Source ProbeThe line-source probe contains a heater that runs the length of the probe (3). The length-to-diameterratio of the probe must be greater than 20. The resistance of the line-source heater must be known to within 60.1 %
35、. The probealso contains a temperature sensor to measure the temperature transient. A typical sensor for the line-source probe is ahigh-sensitivity J-type thermocouple used because of its large Seebeck coefficient. The housing sheath of the probe must be robustenough to ensure that the probe does no
36、t bend or deform under the adverse conditions it is subject to during measurements.7.3 Heater Power SourceThe power input to the line-source heater comes from a DC voltage source. The precision of thevoltage source must be within 60.25 % over the entire duration of the test.7.4 Recording DeviceThe t
37、emperature transient from the line-source probe is recorded for the duration of the test. Atemperature measurement device with a resolution of 0.1C is required. Data are acquired for 30 to 120 s depending on the typeof material. Typical temperature rises are between 2 and 10C over the duration of th
38、e measurement. The frequency of dataacquisition must be at least once every second.7.5 Specimen EnvironmentA constant-temperature environment must be maintained through the duration of the test so as toprovide a temperature stability in the specimen of within 60.1C. Failure to attain this criterion
39、will on occasions compromise thelinearity of the transient, thereby affecting the test result. The environment shall be free from excessive vibration.7.5.1 AmbientFor measurements close to ambient, ambient temperature, use of a stirred water bath is one method to be usedto maintain the test temperat
40、ure. Alternatively, placing the specimen, adequately shielded to protect it from convection, placing inair is a possible alternative.7.5.2 Cryogenic TemperaturesPlacing an a specimen adequately shielded from convection specimen in a controlled cryogenicbath or chamber is acceptable.7.5.3 Elevated Te
41、mperaturesAt temperatures above ambient, a special heated cell is required. This consists of a verticalcylindrical heated chamber, fitted with a removable plug at the bottom. The specimen is loaded from the top and is dischargedthrough the bottom, once the test is complete (see Fig. 2).FIG. 1 Line-S
42、ource TransientD5930 1738. Conditioning8.1 Many thermoplastic materials must be dried because moisture has been shown to affect the properties. Moisture causesmolten polymer samples to foam, which will affect the measured thermal conductivity. Conditioning is generally not a requirementof this test;
43、 if conditioning is necessary, see the applicable material specification or Practice D618.9. Preparation of Test Specimen9.1 The test specimen prepared from samples in the form of plastic pellets, liquids, foams, or soft solids areis acceptable. Thespecimen-preparation method depends on the type of
44、material being tested. If the material is believed to be anisotropic, at leastthree specimens must be tested. Specimens must be longer than the line-source probe and large enough in radius to have at least4 mm of material surrounding the probe, so that the expanding heat wave will not strike a bound
45、ary during the measurement.9.2 Viscous LiquidsThese include pastes and semisolids. Pour or extrude the specimen into a test tube or similar cylindricalcontainer. The container must be filled with sufficient quantity of fluid such that the probe is immersed completely.9.3 Soft SolidsInsert the line-s
46、ource probe directly into the specimen, taking care to see that it does not bend during insertion.TheA specimen of any size or shape as long as it is larger than the minimum specified in 9.1 is acceptable. In the case where thespecimen cannot be penetrated without being destroyed, it is permissible
47、to drill a pilot hole that is smaller than the probe diameterto aid in insertion.9.4 Thermoplastics in the MeltPreheat the sample cell to the lowest melt processing temperature of the thermoplastic. Loadingspecimens at a low temperature is desirable to ensure an air-free specimen. Pour a charge of t
48、he specimen, typically in pellet orpowder form, into the cell and compress into a homogeneous mass. Several charges, tamped well, isare often needed to fill thesample cell. When the specimen is well molten, insert the probe so as to be near the axial center of the specimen. Sealing systemsare someti
49、mes employed to contain the specimen. For thermally unstable materials, follow material manufacturers recommen-dations on temperature exposure limits.9.5 Solid ThermoplasticsLoad the sample in the same manner as in 9.4. The following precautionary steps are needed toaccount for shrinkage of the specimen as it solidifies. The probe shall be fitted with a dynamic sealing system permitting it to movewith the shrinking specimen. Static loads placed on the probe to help maintain contact as the plastic shrinks are acceptable andrecommended. These l
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