Designation:D7028–07´1
Standard Test Method for
Glass Transition Temperature(DMA Tg)of Polymer Matrix Composites by Dynamic Mechanical Analysis(DMA)1
This standard is issued under thefixed designation D7028;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
´1N OTE—Reference to a research report was added andfigures corrected in August2008.
1.Scope
1.1This test method covers the procedure for the determi-nation of the dry or wet(moisture conditioned)glass transition temperature(T g)of polymer matrix composites containing high-modulus,20GPa(>33106psi),fibers using a dynamic mechanical analyzer(DMA)underflexural oscillation mode, which is a specific subset of the Dynamic Mechanical Analysis (DMA)method.
1.2The glass transition temperature is dependent upon the physical property measured,the type of measuring apparatus and the experimental parameters used.The glass transition temperature determined by this test method(referred to as “DMA Tg”)may not be the same as that reported by other measurement techniques on the same test specimen.
1.3This test method is primarily intended for polymer matrix composites reinforced by continuous,oriented,high-modulusfibers.Other materials,such as neat resin,may require non-standard deviations from this test method to achieve meaningful results.
1.4The values stated in SI units are standard.The values given in parentheses are non-standard mathematical conver-sions to common units that are provided for information only.
1.5This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.
2.Referenced Documents
2.1ASTM Standards:2
D3878Terminology for Composite Materials
D4065Practice for Plastics:Dynamic Mechanical Proper-
乙酸乙酯实验
装置ties:Determination and Report of Procedures
D4092Terminology for Plastics:Dynamic Mechanical Properties
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Ma-trix Composite Materials
E177Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1309Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases
E1434Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases
E1471Guide for Identification of Fibers,Fillers,and Core Materials in Computerized Material Property Databases E1640Test Method for Assignment of the Glass Transition Temperature By Dynamic Mechanical Analysis
E1867Test Method for Temperature Calibration of Dy-namic Mechanical Analyzers
3.Terminology
3.1Definitions—Terminology D3878defines terms relating to polymer matrix composites.Terminology D4092defines terms relating to dynamic mechanical property measurements on polymeric materials.
3.2Symbols:
E’=storage modulus
E”=loss modulus
tan d=E”/E’=tangent delta
DMA Tg=glass transition temperature defined from dy-namic mechanical analysis measurement
L=length of specimen
W=width of specimen
T=thickness of specimen
T t=peak temperature from tangent delta curve
4.Summary of Test Method
变压器
油泵4.1Aflat rectangular strip of laminate is placed in the DMA equipment and oscillated at a nominal frequency of1Hz.The specimen is heated at a rate of5°C/min(9°F/min).The same
1This test method is under the jurisdiction of ASTM Committee D30on
Composite Materials and is the direct responsibility of Subcommittee D30.04on
Lamina and Laminate Test Methods.
Current edition approved Dec.15,2007.Published January2008.
2For referenced ASTM standards,visit the ASTM website,,or
contact ASTM Customer Service at For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on
the ASTM website.
1
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loading frequency and heating rate is used for both dry and wet specimens(moisture conditioned)to allow for comparison. The temperature at which a significant drop in storage modulus (E’)begins is assigned as the glass transition temperature (DMA Tg).The peak temperature of the tangent delta curve (T t)is identified along with DMA Tg for comparison purposes.
5.Significance and Use
5.1This test method is designed to determine the glass transition temperature of continuousfiber reinforced polymer composites using the DMA method.The DMA Tg value is frequently used to indicate the upper use temperature of composite materials,as well as for quality control of composite materials.
6.Interferences
6.1The standard testing machine shall be of the Dynamic Mechanical Analysis(DMA)type of instrument that operates with forced oscillation and applies aflexural loading mode (either three-point bend or dual cantilever)to the test specimen. Refer to Practice D4065for a summary of various other DMA practices.Other loading modes(such as tensile,torsion or shear)may produce different test results.If another equipment type or loading mode is used the non-standard approach shall be described in the report and the test result recorded as non-standard.
6.2Afixed frequency of1Hz is standard in this test method. In general,for a given material,a higher testing frequency produces a higher DMA Tg value than this standard,while use of the resonance mode will yield a different DMA Tg that may be either higher or lower than the standard.If a non-stan
dard frequency,or the resonance mode,is used,the non-standard approach shall be described in the report and the test result recorded as non-standard.
6.3A heating rate of561°C/min(962°F/min)is standard in this test method.A change in heating rate will affect the glass transition temperature result;the standard heating rate is the best available compromise for comparing DMA Tg results of dry and wet laminates.If a different heating rate is used it shall be described in the report and the result recorded as non-standard.
N OTE1—Users should be advised that a heating rate of5°C/min represents a compromise between various issues related to Tg measure-ment precision and bias.It is widely known that heat transfer limitations are more pronounced in DMA apparatus compared to other thermal analysis techniques,such as differential scanning calorimetry(DSC)and thermomechanical analysis(TMA).For greatest precision,it has been recommended that heating rates be2°C/min or less.Test Method E1640 specifies a heating rate of1°C/min.However,in many cases5°C/min is recommended as a compromise between Tg measurement accuracy and test method convenience,especially for wet laminate measurements,since the slower heating rate will cause specimen drying that will itself bias the results.
6.4Purge gas type andflow rate and the position of the thermocouple can affect the DMA Tg test result and shall be noted and reported.The same conditions shall be used for both calibration and testing runs.Instrumentation manufacturer recommendations should be followed.
6.5It is standard in this test method that one of the major fiber directions shall be parallel to the length of the specimen.The span-to-depth ratio,ply orientation,and ply stacking sequence of a specimen with respect to the testingfixture have a profound effect on the DMA Tg result.A meaningful comparison of data requires that the specimen configuration be the same.A non-standard specimen configuration shall be described in the report and the result recorded as non-standard.
6.6The standard definition in this test method for DMA Tg is based on intersecting two tangent lines from a semi-logarithmic plot of the storage modulus versus temperature. Other T g definitions typically produce different test results.For example,a linear plot scale will result in a lower value of DMA Tg.A non-standard DMA Tg definition shall be described in the report and the result recorded as non-standard.For com-parison purposes the peak temperature of the tangent delta curve(T t)is identified along with DMA Tg.
7.Apparatus
7.1Micrometer,suitable for reading to0.025mm(0.001in.) accuracy for measuring the specimen thickness and width. 7.2Caliper,suitable for reading to0.025mm(0.001in.) accuracy for measuring the specimen length and instrument clamping distance.
7.3Dynamic Mechanical Analyzer(DMA),with oven ca-pable of heating to above the glass transition temperature and of controlling the heating rate to the specified value.
8.Sampling and Test Specimens
8.1Two specimens shall be tested for each sample.If the testing is part of a designed experiment,other sampling techniques may be used if described in the test plan.
8.2Consult the instrument manufacturer’s manual for speci-men size.A span-to-thickness ratio greater than ten is recom-mended.Specimen absolute size is notfixed by this method as various dynamic mechanical analyzers require different sizes. Depending on the analyzer,typical specimen size can range from56643126132.060.5mm(2.2160.1630.47 60.0430.0860.02in.)(L3W3T)to22613361 31.060.5mm(0.960.0430.1260.0430.0460.02 in.).
8.3One of the majorfiber directions in the specimen shall be oriented along the length axis of the spe
cimen.It is standard that one of the majorfiber directions shall be parallel to the length of the specimen,and specimens containing only off-axis plies shall not be used.Any deviations from the standard orientation shall be reported and the test results noted as non-standard.
8.4The specimen surfaces shall beflat,clean,straight,and dry to prevent slippage in the grips and mitigate any effects due to moisture.Opposite surfaces must be essentially parallel and intersecting surfaces perpendicular.Tolerances in thickness and width must be better than62%.
8.5The selected sample shall be taken from a representative portion of the laminate.Laminate edges or other irregularities created in the laminate by mold or bagging techniques should be avoided.
9.Calibration
9.1The DMA equipment shall be calibrated in accordance with Test Method E1867for temperature signals and
in 2
accordance with the equipment manufacturer’s recommenda-tion for the storage modulus.The equipment must be calibrated in the same loading mode as will be used for testing,either dual cantilever or three-point bending.The temperature calibration points must span the DMA Tg result.
10.1Moisture has significant effect on DMA Tg.Therefore, it is recommended that the test specimens should be weighed before and after DMA Tg testing to quantify the moisture change in the specimen resulting from the DMA Tg test. 10.2Dry Specimens—To minimize the presence of moisture in the specimens,dry specimens must be conditioned prior to testing by using either of the following techniques:
10.2.1Dry the specimens in an oven in accordance with Test Method D5229/D5229M,Procedure D,then stored until test in a desiccator or sealed MIL-PRF-1313(or equivalent) aluminized bag,or风力摆控制系统
10.2.2Store the material in a desiccator or sealed alumi-nized bag immediately after material curing(lamination), where the material shall remain except for the minimum time required for removal during specimen preparation and testing. The maximum time between cure(lamination)and testing shall be30days,after which,prior to testing,specimens shall be oven-dried in accordance with10.2.1.
10.3Wet Specimens—Condition in accordance with Test Method D5229/D5229M,Procedure B.The conditioned specimens shall be tested within30minutes after removal from the conditioning chamber,or stored in sealed MIL-PRF-131(or equivalent)aluminized bag until test.
11.Procedure
11.1Test Specimen—Measure the specimen thickness and width to0.025mm(0.001in.)and record.Measure the specimen length to0.025mm(0.001in.)and record.Weigh the specimen to the nearest milligram(0.001g)and record. 11.2Specimen Installation—Install the specimen in the DMA test equipment oven based upon clamping method to be employed.
11.3Positioning of Specimen—Follow the manufacturer’s procedure for positioning the specimen in the clamps.Gener-ally,the specimen should be centered between the clamp faces and be parallel to the base of the instrument.Mount the specimen in dual cantilever mode or three-point bending mode.
11.4Heating Rate—The standard heating rate is56 1°C/min(962°F/min).The same heating rate shall be used for all samples whose results are to be compared.Any deviations from this heating rate shall be noted in the report and the result shall be reported as non-standard.
11.5Frequency—The standard frequency to be used in this standard is1Hz,and the instrument should be operated in constant strain mode.
11.6Strain Amplitude—The maximum strain amplitude should be kept within the linear viscoelastic range of the material.Strains of less than0.1%are standard.
11.7Temperature Range—Program the run to begin at room temperature or a temperature at least50°C(90°F)below the estimated DMA Tg and to end at a temperature at least50°C (90°F)above DMA Tg,but below decomposition temperature.
11.8Purge Gas Flow Rate—Follow the manufacturer’s manual or recommendations to set the purge gasflow rate.Five litres/minute(0.2CFM)is a typical purge gasflow rate setting. For some types of dynamic mechanical analyzers,a purge gas flow setting is not required.
工艺
拖鞋11.9Thermocouple Positioning—Follow the manufactur-er’s manual or recommendations to position the thermocouple. Typically the thermocouple should be as close to the sample as possible.11.10Test—Conduct DMA Tg measurements using the instrument settings specified and record the load and displace-ment data as a function of temperature.Allow the oven to cool before removing the
specimen.Weigh the specimen after the test to the nearest milligram(0.001g)after the removal from the oven and record.
11.11Specimen Examination—Examine the specimen after the test and inspect for any visual anomalies(that is,delami-nation,blisters,cracks,etc.).Record any visual anomalies observed.
12.Interpretation of Results
12.1Glass Transition Temperature(DMA Tg)—Plot the logarithm of storage modulus(E’)and linear tangent delta(tan d)versus the linear temperature(Fig.1).During the glass transition,the storage modulus of the composite material is significantly reduced.The DMA Tg is determined to be the intersection of two tangent lines from the storage modulus by this test method.Thefirst tangent line(Line A,Fig.1)is selected at a temperature before the transition.This tempera-ture is designated as TA.The second tangent line(Line B,Fig.
1)is constructed at the inflection point to approximately the midpoint of the storage modulus drop.This temperature is designated as TB.The two tangent lines are intersected,and temperature corresponding to this intersection point is recorded as the DMA Tg.See Appendix X1for additional guidelines to draw tangent lines.
12.2Tangent Delta(d)peak(T t)—The peak temperature of the tangent delta curve(T t)is identified and reported(Fig.1).
13.Validation
13.1Any specimen that has an obviousflaw or deviation from the requirements of this test method may be rejected.A new or spare specimen shall be prepared from the same material package and tested to replace any specimens rejected per this paragraph.
13.2Test results may be discarded for any conditions which compromise the integrity of the test.Should the results be retained,then these conditions shall be described in the test report.Specific examples include:
13.2.1Cracks evident in the specimen after the test.This could indicate that the sample was taken from a defective portion of the laminate.
3MIL-PRF-131,Barrier Materials,Watervaporproof,Greaseproof,Flexible, Heat-Sealable.Available at assist.daps.dla.mil or from the Standardization Document Order Desk,700Robbins Avenue,Building4D,Philadelphia,PA
19111-5094.
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13.2.2An irregularity of the plotted curve,such as change in slope,other than that due to the glass transition,or excessive noise.It is possible that more than one transition exists,but this should be confirmed by a separate run.
13.2.3Slippage of the specimen in the grips.
14.Report
14.1Report the following information,or references point-ing to other documentation containing this information,to the maximum extent applicable (reporting of items beyond the control of a given testing laboratory,such as might occur with material details or panel fabrication parameters,shall be the responsibility of the requestor):
N OTE 2—Guides E 1309,E 1434,and E 1471contain data reporting recommendations for composite materials and composite materials me-chanical testing.
14.1.1The revision level or date of issue of this test method.14.1.2The name(s)of the test operator(s).
14.1.3Any variations to this test method,anomalies noticed during testing,or equipment problems occurring during testing.14.1.4Identification of all the materials constituent to the plate specimen tested,including for each:material specifica-tion,material type,manufacturer’s material designation,manu-facturer’s batch or lot number,source (if not from manufac-turer),date of certification,expiration of certification,filament diameter,tow or yarn filament count and twist,sizing,form or weave,fiber areal weight,matrix type,matrix content,and volatiles content.
14.1.5Description of the fabrication steps used to prepare the parent laminate including:fabrication start date,fabrication end date,process specification,cure cycle,consolidation method,and a description of the equipment used.
14.1.6Ply orientation and stacking sequence of the lami-nate,relative to the longitudinal (long)dimension.
14.1.7If requested,report density,volume percent rein-forcement,and void content test methods,specimen sampling method and geometries,test parameters,and test results.
14.1.8Method of preparing the test specimen,including specimen labeling scheme and method,specimen geometry,sampling method,and specimen cutting method.
14.1.9Calibration dates and methods for all measurements and test equipment.
14.2Report the following information:14.2.1Date of test.
14.2.2Test span length and thickness.
14.2.3Specimen conditioning history including weight gain or weight loss of specimen.
14.2.4Instrument brand name,type,or model number.14.2.5Specimen loading condition and clamping details.14.2.6Heating rate and loading frequency.14.2.7Flow rate and type of the purge gas.
14.2.8Any non-standard testing or data reduction param-eters,including heating rate and loading frequency.14.2.9Deformation amplitude or strain.
14.2.10Test results,including DMA Tg,peak tangent delta value (T t ),TA,TB,the method for DMA Tg determination,and comments on any irregularities or unexpected results.
14.2.11Sample weight before and after DMA Tg testing and weight loss percentage.
15.Precision and Bias 415.1Precision :
15.1.1The precision of the DMA Tg measurements depend on strict adherence to this test method and are influenced by mechanical and material factors,specimen preparation,and measurement errors.
4
A research report is available from ASTM Headquarters.Requst
RR:D30-1004.
FIG.1Construction of Storage Modulus Glass Transition
Temperature
4
15.1.2Mechanical factors that can affect the test results include:the physical characteristics of the DMA testing equip-ment (stiffness,damping,and mass),accuracy of the loading and deflection measurements,loading frequency,alignment of the test specimen in the clamping device,clamping distance,thermocouple location.
15.1.3Material factors that can affect test results include:material quality and representativeness,sampling scheme,and specimen preparation (surface quality,flatness,fiber alignment,aspect ratio,and so forth).
15.1.4An interlaboratory test program was conducted where an average of two specimens each,of four different materials and layup configurations,were tested by seven different laboratories.The specimens were conditioned to both dry and wet environments per Test Method D 5229/D 5229M .Table 1presents the precision statistics generated from this study as defined in Practice E 691for DMA Tg dry and wet values.The materials listed in Table 1are defined as:
A Glass/Epoxy Fabric -(90/0)10layup
B Carbon/Epoxy Tape -(90/0)2s layup
C Carbon/Bismaleimide Tape -(90/0)2s layup D
Carbon/Bismaleimide Fabric -(90/0)12layup
15.1.5The averages of the coefficient of variation are shown in Table 2.The values of S r /X and S R /X represent the repeat-ability and the reproducibility coefficients of variation.These averages allow a relative comparison of the repeatability (within laboratory precision)and reproducibility (between laboratory precision)of the DMA Tg test parameters.These values indicate that the material factors did not have a significant impact on repeatability and reproducibility of the DMA Tg values measured.
The DMA Tg dry values were found to exhibit higher repeatability and reproducibility than the DMA Tg wet values.
15.2Bias —Bias cannot be determined for this test method as no acceptable reference standard exists.16.Keywords
16.1composite;DMA;dynamic mechanical analysis;glass transition temperature;polymer matrix composite
TABLE 1Precision Statistics
Material
X
–S r
S R
r
R
S r /X –,%
S R /X –,%
DMA Tg (°C),Dry
A 1290.33 5.830.9316.30.26 4.53
基因
测序仪
B 176 1.75 6.70 4.9118.8 1.00 3.82
C 256 1.129.19 3.1325.70.44 3.59D
262
1.69
7.16
4.73
20.1
0.65
2.74
DMA Tg (°C),Wet
A 79 1.03 6.55 2.8818.3 1.308.31
B 120 1.417.03 3.9619.7 1.18 5.85
C 1900.417.70 1.1421.60.22 4.06D
190
2.27
9.23
6.35
25.9
1.19
4.85
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