Designation:D5930−09
Standard Test Method for
Thermal Conductivity of Plastics by Means of a Transient Line-Source Technique1
This standard is issued under thefixed designation D5930;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
1.Scope*
1.1This test method covers the determination of the thermal conductivity of plastics over a temperature range from–40to 400°C.The thermal conductivity of materials in the range from 0.08to
2.0W/m.K can be measured covering thermoplastics, thermots,and rubbers,filled and reinforced.
1.2The values stated in SI units shall be regarded as standard.
1.3This standard does not purport to address the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish proper safety and health practices and determine the applicability of regulatory limitations prior to u.
N OTE1—There is no known ISO equivalent to this test method.
2.Referenced Documents
2.1ASTM Standards:2
C177Test Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus
C518Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus C1113Test Method for Thermal Conductivity of Refracto-ries by Hot Wire(Platinum Resistance Thermometer Technique)
D618Practice for Conditioning Plastics for Testing
vaccine是什么疫苗名称D883Terminology Relating to Plastics
D2717Test Method for Thermal Conductivity of Liquids E177Practice for U of the Terms Precision and Bias in ASTM Test Methods
E1225Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique 3.Terminology
3.1Definitions—Terminology ud in this standard is in accordance with Terminology D883.
3.2Definitions of Terms Specific to This Standard:
3.2.1temperature transient,n—the temperature ri associ-ated with the perturbation of a system,initially at a uniform temperature.The system does not attain thermal equilibrium during the transient.
3.2.2thermal conductivity,n—the time rate of steady heat flow/unit area through unit thickness of a homogeneous mate-rial in a direction perpendicular to the surface induced by a unit temperature difference.
3.2.2.1Discussion—Where other modes of heat transfer are prent in addition to conduction,such as convection and radiation,this property often is referred to as the apparent thermal conductivity,l app.
3.2.2.2Discussion—Thermal conductivity must be associ-ated with the conditions under which it is measured,such as temperature and pressure,as well as the compositional varia-tion of the material.Thermal conductivity may vary with direction and orientation of the specimen since some materials are not isotropic with respect to thermal conductivity.In the ca of thermot polymers,thermal conductivity may vary with the extent of cure.
3.2.3thermal diffusivity—a heat-transport property given by the thermal conductivity divided by the thermal mass,which is
a product of the density and the heat capacity.
3.3Symbols:
3.3.1C—Probe constant.
3.3.2l—Thermal conductivity,W/m.K.
disaster3.3.3Q—Heat output per unit length,W/m.
3.3.4T2—The temperature(K)recorded at time t2.
3.3.5T1—The temperature(K)recorded at time t1.
3.4Subscript:
3.4.1av—average.
3.4.2app—apparent.
3.4.3ref—reference.
1This test method is under the jurisdiction of ASTM Committee D20on Plastics
and is the direct responsibility of Subcommittee D20.30on Thermal Properties.
oil是什么意思
Current edition approved Aug.15,2009.Published September2009.Originally
approved in1997.Last previous edition approved in2001as D5930-01.DOI:
10.1520/D5930-09.
2For referenced ASTM standards,visit the ASTM website,www.astm,or
contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on
the ASTM website.
*A Summary of Changes ction appears at the end of this standard Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United States
4.Summary of Test Method
4.1Line-Source Technique—This is a transient method for determining thermal conductivity(1,2).3A line source of heat is located at the center of the specimen being tested.The apparatus is at a consta
nt initial temperature.During the cour of the measurement,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 polymer.The temperature ri of the line-source varies linearly with the logarithm of time(3).This relationship can be ud directly to calculate the thermal conductivity of the sample.The line-source of heat can be achieved in a number of ways.In this test method,it is in the form of a probe as described in7.2.
5.Significance and U
5.1The relative simplicity of the test method makes it applicable for a wide range of materials(4,5).The technique
is capable of fast measurements,making it possible to take data before the materials suffer thermal degradation.Alternatively, it is possible to study the effect of compositional changes such as chemical reaction or aging(6).Short measurement times permit generation of large amounts of data with little effort. The line-source probe and the accompanying test specimen are small in size,making it possible to subject the sample to a wide range of test conditions.Becau this test method does not contain a numerical precision and bias statement,it shall not be ud as a referee test method in ca of dispute.
6.Interferences
6.1The line-source method produces results of highest precision with materials where intimate contact with the probe can be established,thereby eliminating effects of thermal contact resistance.The materials include viscousfluids and soft solids.
6.1.1Thermal-Contact Resistance—In the solid state,a contact resistance can develop due to the interface between the specimen and the measuring device.Conventional methods attempt to account for this by introducing a conductive paste between the specimen and the nsor.This reduces,but may not eliminate,the effect of contact resistance.In the line-source method,contact resistance manifests itlf as a nonlinearity in the initial portion of the transient(e Fig.1).The technique has a method to account for this phenomenon.By extending the time of the measurement,it is possible to progress beyond the region of thermal-contact resistance,achieving a state where the contact resistance does not contribute to the mea-sured transient(7).This state typically is achieved after about 10to20s in the measurement.The larger the contact resistance,the greater is this time.It is,therefore,important to make a sufficiently long measurement to exclude the portion of the transient that shows the effect of the contact resistance.The duration of measurement,however,cannot be too long,or el the heat wave can strike a sample boundary,there
by violating the theoretical conditions of the measurement.ideology
versace是什么意思6.1.2Shrinkage Upon Solidification—Plastics tend to shrink significantly upon solidification.This shrinkage is especially so for the mi-crystalline materials,which experience a signifi-cant change in specific volume upon crystallization.This crystallization can result in large gaps being developed be-tween the specimen and the nsing device.To account for shrinkage,a simple compression scheme described in9.5can permit the line-source probe to move downward to take up the slack.Steps also must be taken to minimize specimen volume so as to reduce the extent of shrinkage.
6.2Measurements on in viscidfluids are subject to the development of convection currents which can affect the measurement.Becau of the transient nature of the measurement,the effects are not as pronounced.They cannot be eliminated,however.
6.3Although the technique is not limited by temperature,at measurements above500°C,a significant amount of heat transfer occurs due to radiation so that only a l app can be measured.
7.Apparatus
7.1The apparatus consists of a line-source probe imbedded in a specimen contained in a constant-te
keep up withmperature environ-ment.During the measurement,the line-source probe produces a preci amount of heat.The resulting temperature transient is recorded,preferably,on a computer data-acquisition system,as specified in7.4.This transient is analyzed to obtain the thermal conductivity.
7.2Line-Source Probe—The line-source probe contains a heater that runs the length of the probe(3).The length-to-diameter ratio of the probe must be greater than20.The resistance of the line-source heater must be known to within 60.1%.The probe also contains a temperature nsor to measure the temperature transient.A typical nsor for the line-source probe is a high-nsitivity J-type thermocouple ud becau of its large Seebeck coefficient.The housing sheath of the probe must be robust enough to ensure that the probe does not bend or deform under the adver conditions it is subject to during measurements.
3The boldface numbers in parenthes refer to the list of references at the end of this
standard.FIG.1Line-Source
Transient
7.3Heater Power Source—The power input to the line-source heater comes from a DC voltage source.The precision of the voltage source must be within 60.25%over the entire duration of the test.
7.4Recording Device—The temperature transient from the line-source probe is recorded for the duration of the test.A temperature measurement device with a resolution of 0.1°C is required.Data are acquired for 30to 120s depending on the type of material.Typical temperature ris are between 2and 10°C over the duration of the measurement.The frequency of data acquisition must be at least once every cond.7.5Specimen Environment—A constant-temperature envi-ronment must be maintained through the duration of the test so as to provide a temperature stability in the specimen of within 60.1°C.Failure to attain this criterion can compromi the linearity of the transient,thereby affecting the test result.The environment shall be free from excessive vibration.
7.5.1Ambient—For measurements clo to ambient,a stirred water bath may be ud to maintain the test temperature.Alternatively,the specimen,adequately shielded to protect it from convection,may be placed in air.
7.5.2Cryogenic Temperatures—The specimen,adequately shielded to protect it from convection,may be placed in a controlled cryogenic bath or chamber.
7.5.3Elevated Temperatures—At temperatures above ambient,a special heated cell is required.This consists of a vertical cylindrical heated chamber,fitted with a removable plug at the bottom.The specimen is loaded from the top and can be discharged through the bottom,once the test is complete (e Fig.2).8.Conditioning
8.1Many thermoplastic materials must be dried becau moisture can affect the properties.Moisture caus molten
polymer samples to foam,which will affect the measured thermal conductivity.Conditioning is generally not a require-ment of this test;if conditioning is necessary,e the applicable material specification or Practice D618.9.Preparation of Test Specimen
9.1The test specimen may be prepared from samples,which can be in the form of plastic pellets,liquids,foams,or soft solids.The specimen-preparation method depends on the type of material being tested.If the material is believed to be anisotropic,at least three specimens must be tested.Specimens must be longer than the line-source probe and large enough in radius to have at least 4mm of material surrounding the probe,so that the expanding heat wave will not strike a boundary during the measurement.
9.2Viscous Liquids—The include pastes and misolids.Pour or extrude the specimen into a test tube or similar cylindrical container.The container must be filled with suffi-cient quantity of fluid such that the probe is immerd completely.
9.3Soft Solids—Inrt the line-source probe directly into the specimen,taking care to e that it does not bend during inrtion.The specimen can be of any size or shape as long as it is larger than the minimum specified in 9.1.In the ca where the specimen cannot be penetrated without being destroyed,it is permissible to drill a pilot hole that is smaller than the probe diameter to aid in inrtion.
9.4Thermoplastics in the Melt—Preheat the sample cell to the lowest melt processing temperature of the thermoplastic.Loading specimens at a low temperature is desirable to ensure an air-free specimen.Pour a charge of the specimen,typically in pellet or powder form,into the cell and compress into a homogeneous mass.Several charges,tamped well,may be needed to fill the sample cell.When the specimen is well molten,inrt the probe so as to be near the axial center of the specimen.Sealing systems may be employed to contain the specimen.For thermally unstable materials,follow material manufacturers’recommendations on temperature exposure limits.
9.5Solid Thermoplastics—Load the sample in the same manner as in 9.4.The following precautionary steps are needed to account for shrinkage of the specimen as it solidifies.The probe shall be fitted with a dynamic aling system permitting it to move with the shrinking specimen.Static loads can then be placed on the probe to help maintain contact as the plastic shrinks.The loads optimally will apply a pressure of 1to 7MPa on the specimen.
9.6Thermots and Rubber—Preheat the sample cell to a loading temperature,above the glass transition,where the specimen is fluid enough to be molded but will not undergo significant reaction (6).If the sample cell is to be reud,wipe the walls of the cell with a thin layer of a relea agent such as silicone oil to prevent the cured specimen from bonding to the cell.Charge or pour the uncur
ed specimen in the same manner as in 9.4.For best results,do not coat the probe with relea agents since this might affect the test
results.宁波自考办
FIG.2Adaptation for Measurements at Elevated
Temperatures
10.Calibration
10.1The actual probe and sample cell differ in many ways from the theoretical situation,which assumes an infinitely long probe in an infinite specimen.Some of the non-idealities can be minimized by judicious design of the probe and sample cell.Practical limitations in probe construction,however,are such that a calibration is necessary to account for such effects as the thermal mass of the probe and the fact that the preci length of the line-source cannot be determin
ed.A probe constant must be obtained by calibrating the probe against a material of known thermal conductivity.The constant depends on the probe characteristics and has no significant temperature nsi-tivity.The ideal value of the probe constant is 1.0.Typical values range from 0.8to 0.9.视频英文
10.2Reference Material—An ideal reference material is a well-characterized,viscous liquid.Such a system will not be subject to thermal contact resistance effects.Becau of the high viscosity,convection effects are not prent.A polydim-ethylsiloxane fluid 4is in common u as a reference material.This material has a thermal conductivity of 0.16W/m.K at room temperature (8,9).
10.3Probe Calibration—In the equations in 12.2,the probe constant is t to 1.0.The line-source probe is immerd in the reference material of known thermal conductivity l ref ,which is at the reference temperature.At least five measurements must be performed as outlined in Section 11.The resulting values of thermal conductivity are calculated bad on 12.2,for each ca and the results averaged yielding l av .
C 5l ref /l av
(1)
Calibration should be verified at least once a month.11.Procedure
11.1Before beginning experiments,examine the line-source probe.The probe must be straight and its surface free of residues,oil,or water.Nonresidue solvents and copper gauze are recommended for cleaning.The sample cell must be clean and free of residues.
11.2Prepare the specimen and inrt the probe as applicable for the appropriate sample type,as described in Section 9.Ensure that the probe is cure and the system is not subject to any form of vibration or temperature fluctuation.
11.3In general,low power outputs are desirable to prevent excessive perturbation of the system.The amount of power input to the line-source heater is dependent on the character-istics of the material being tested.A high-thermal-diffusivity material dissipates heat at a faster rate so that a larger amount of heat is needed.Converly,low-thermal-diffusivity materials,such as foams and insulations require a small amount of heat input.
aghast11.4Allow the system to attain temperature stability,as defined in the criteria in 7.5.Supply the heat input to the line-source.Simultaneously,record the temperature and time for the duration of the measurement.
11.5Multiple measurements may be made if desired at the same conditions,provided that the syst
em is permitted to stabilize prior to each measurement.
11.6Change the sample environment conditions for the next measurement.Continue the process until the desired range of test conditions have been covered.Where a change of physical state occurs over the range of conditions tested,acquire at least two measurements in each state.
11.7Clean up the system by extracting the probe under the same conditions as tho under which it was loaded.The only exception to this rule is in the ca of thermots where the specimen has solidified around the probe.Rubbers can be cut away from the probe using a sharp razor.Rigid thermots may be removed by thermal decomposition using a Bunn burner.This procedure must be performed with adequate fume re-moval.The probe temperature must be monitored so that it does not exceed permissible limits.Remove all adhering materials.Do not scratch,mar,or bend the probe during cleaning.
11.8Inspect the specimen for voids.If specimen has been subjected to conditions where it might have undergone degradation,note and report such evidence.12.Calculation
12.1Plot the temperature ri against log time.Obtain the slope of the linear portion of the curve.Neglect initial nonlinearities,which occur becau of the heat wave propa-gating through the w
alls of the probe and also due to contact resistance,where the phenomenon exists (7).
12.2Perform the calculations using the following equation:
l 5
C Q 1
4p Slope
(2)
where:
Slope 5
T 22T 1
~21!
K
(3)
12.3Test Conditions—The temperature at which the thermal conductivity is to be reported is the equilibrium temperature of the specimen prior to the start of the measurement,reported to the nearest whole number.If the time of the measurement is to be recorded,report the time at the start of the measurement.Report any other conditions that are unique to the measure-ment.13.Report
13.1Report the following information:
13.1.1Description of the material and test specimen.13.1.2Description of the apparatus.
13.1.3Reference material ud for calibration including its thermal conductivity value.
13.1.4Details of the probe,including probe constant,length,and power output.
13.1.5Thermal conductivity at the relevant test conditions,such as temperature or time.
13.2Report if the specimen has undergone any physical or chemical change during testing.
4
Polydimethylsiloxane,trimethylsiloxyteminated,60,000CS,from Huls America,Bristol,PA
19007.
14.Precision and Bias
14.1Table 1is bad on a repeatability study involving a single laboratory.The materials ud were unfilled polypropyl-ene and polycarbonate resins.Measurements were performed by a single technician on a single day.Each test result is an individual determination.Five measurements were obtained for each material.
14.2Attempts to develop a full precision and bias statement for this test method have not been successful.Becau this test method does not contain round-robin bad precision data,it shall not be ud as a referee test method in ca of dispute.Anyone wishing to participate in the development of precision and bias data should contact the Chairman,Subcommittee D20.30(Section D20.30.07),ASTM,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428–2959.14.3Th
ere are no recognized standards on which to ba an estimate of bias for this test method.15.Keywords
15.1line-source probe;line-source technique;plastics;rub-ber;thermal conductivity;thermoplastics;thermots
REFERENCES
(1)Hooper,F.C.,and Lepper,F.R.,Trans.Am.Soc.Heat.Vent.Engrs.,
V ol 56,1950,p.309.
(2)Eustachio,D.,and Schreiner,R.E.,Trans.Am.Soc.Heat.Vent.
Engrs.,V ol 58,1952,p.331.
(3)Lobo,H.,and Cohen,C.,Polym.Eng.Sci.,V ol 30,1990,p.65.(4)Haugh,C.H.,and Sweat,V .E.,Trans.ASAE,V ol 56,1974.
(5)McTaggart,R.B.,and Underwood,W.M.,“Heat Transfer (Storrs),”
Chem.Eng.Prog.Sym.Series,V ol 56,No.30,1960,p.261.(6)Lobo,H.,SPE Technical Papers ,V ol XXXVIII,1991,p.1281.(7)Tye,R.P.,ed.,“Thermal Conductivity,”V ol 2,p.377.
(8)Bates,O.K.,Ind.Eng.Chem.,V ol 41,No.9,1949,p.1966.
(9)
“Silicon Compounds Register and Review,”Petrarch Systems,Inc.,1984,p.190.
SUMMARY OF CHANGES
Committee D20has identified the location of lected changes to this standard since the last issue (D5930-01)that may impact the u of this standard.(August 15,2009)
(1)Checked and revid standard for permissive language usage.
(2)Revid 8.1to improve clarity.
(3)Revid 3.2.2.2and 11.7to clarify the testing of thermo-ts.
(4)Revid to 11.5and 11.6to move text for improved relevance of information.
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TABLE 1Repeatability Data for Thermal Conductivity (W/m·K)of
Polypropylene and Polycarbonate
wearinessMaterial Test
Temperature,
°C
Average S r A r B
Polypropylene 2000.1640.00190.0053Polycarbonate
280
0.263
0.0058
0.0162
A S r =within-laboratory standard deviation of the average.B
r =within-laboratory repeatability limit =2.8×S r
.
