1、Designation: E1142 14Standard TerminologyRelating to Thermophysical Properties1This standard is issued under the fixed designation E1142; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parent
2、heses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This is a compilation of terms and correspondingdefinitions commonly used in the study of thermophysicalproperties. Terms that are generally understood
3、 or definedadequately in other readily available sources are either notincluded or their sources identified.1.2 A definition is a single sentence with additional infor-mation included in a Discussion. It is reviewed every fiveyears, and the year of the last review or revision is appended.1.3 Definit
4、ions identical to those published by anotherstandards organization orASTM Committee are identified withthe abbreviation of the name of the organization or theidentifying document and ASTM Committee.1.4 Definitions of terms specific to a particular field (such asdynamic mechanical measurements) are i
5、dentified with anitalicized introductory phrase.2. Referenced Documents2.1 ASTM Standards:2D4092 Terminology for Plastics: Dynamic MechanicalPropertiesE7 Terminology Relating to MetallographyE344 Terminology Relating to Thermometry and Hydrom-etry3. Terminology3.1 Definitions:absolute pressure, npre
6、ssure measured relative to zeropressure corresponding to empty space.DISCUSSIONAbsolute pressure is atmospheric pressure plus gagepressure.activation energy (E), nin chemical kinetics, the energy thatmust be overcome in order for a chemical reaction to occur.DISCUSSIONThe term activation energy was
7、introduced in 1889 bySvante Arrhenius as a mathematical term in the eponymous, empiricalrelationship between temperature and reaction rate constant.admittance, Y, nthe reciprocal of impedance.alpha () loss peak, nin dynamic mechanical measurement,first peak in the damping curve below the melt, in or
8、der ofdecreasing temperature or increasing frequency. E7angular frequency, , nthe number of radians per secondtraversed by a rotating vector that represents any periodicallyvarying quantity.DISCUSSIONAngular frequency, , is equal to two times thefrequency, f.anisotropic, adjhaving different values f
9、or a property indifferent directions.anti-thixotropy, nan increase of the apparent viscosity underconstant shear stress or shear rate followed by a gradualrecovery when the stress or shear rate is reduced to zero.arrhenius equation, na mathematical relationship betweenthe specific reaction rate and
10、the temperature given as:k 5 Ae2E/RT(1)where:k is the reaction rate constant, A is the frequency factor, E isthe energy of activation, R is the gas constant, and T is theabsolute temperature.barometer, nAn instrument for measuring atmospheric pres-sure.beta () loss peak, nin dynamic mechanical measu
11、rement,second discrete peak in damping curve below the melt, inorder of decreasing temperature or increasing frequency.D4092boiling pressure, nat a specific temperature, the value of thevapor pressure of the liquid at which it is equal to theexternal pressure.boiling temperature, nat a specific pres
12、sure, the tempera-ture at which the vapor pressure of the liquid is equal to theexternal pressure.capacitance, nthat property of a system of conductors anddielectrics that permits the storage of electrical charge whena potential difference exists between the conductors.1This terminology is under the
13、 jurisdiction of ASTM Committee E37 onThermal Measurements and are the direct responsibility of Subcommittee E37.03 onNomenclature and Definitions.Current edition approved Feb. 15, 2014. Published February 2014. Originallyapproved in 1988. Last previous edition approved in 2013 as E1142 13. DOI:10.1
14、520/E1142-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Dr
15、ive, PO Box C700, West Conshohocken, PA 19428-2959. United States1DISCUSSIONCapacitance is the ratio of a quantity of electric charge,Q, to a potential difference, V. A capacitance value is always positive.The unit of capacitance is the farad, F, which is equivalent to onecoulomb per volt.catalyst,
16、na substance that increases the rate of a chemicalreaction but is not consumed or changed by that reaction.Celsius, ndesignation of the degree on the InternationalPractical Temperature Scale; also used for the name of thescale, as “Celsius Temperature Scale.” Formerly (prior to1948) called “Centigra
17、de.” The Celsius temperature scale isrelated to the International Kelvin Temperature Scale by theequation: Tc=T 273.16 K.Centigrade, nsee Celsius.coeffcient of expansion, nsee coefficient of linear thermalexpansion.coefficient of linear thermal expansion, l, nchange inlength, relative to the length
18、of the specimen, accompanyinga unit change of temperature, at a specified temperature.coefficient of viscosity, nthe ratio between an infinitesimallysmall increase in stress and the corresponding increase instrain rate.coefficient of volume thermal expansion v, nfor a solid orliquid, the change in v
19、olume, relative to the volume of thespecimen, accompanying a change of temperature at aspecified temperature.color temperature, ntemperature in degrees Kelvin (K) atwhich a black body must be operated to give a color equal tothat of the source in plex modulus, E*,G*, or K*, nratio of the stress tost
20、rain where each is a factor that may be represented by acomplex number as follows: E*=E+iE“,G*=G+iG“,and K*=K+iK“.where:E* = complex modulus, measured in tension or flexure,E = storage modulus, measured in tension or flexure,E9 = loss modulus, measured in tension or flexure,G* = complex modulus, mea
21、sured in shear,G = storage modulus, measured in shear,G9 = loss modulus, measured in shear,K* = complex modulus, measured in compression,K = storage modulus, measured in compressionK9 = loss modulus, measured in compression, andi 521 , measured in compression.The complex modulus may be measured in t
22、ension orflexure, (E*), compression, (K*), or in shear, (G*). D4092complex shear compliance, J*, nreciprocal of complexshear modulus, where J* = 1/G*. D4092complex tensile compliance, D*, nreciprocal of complextensile modulus, where D*=1/E*. D4092complex viscosity, *, nthe complex modulus divided by
23、 theimposed frequency in rad/pliance, J, nthe strain divided by the correspondingstress.DISCUSSIONCompliance is the reciprocal of position, nquantity of the components of a mixture;usually expressed in terms of the weight percentage, or theatomic percentage of each of the components in the mixture.E
24、7conductivity, electrical (volume), , nthe ratio of thecurrent density (Acm2) through a specimen to the potentialgradient (V/cm) in the same direction as the current.DISCUSSIONConductivity is normally expressed in units(ohmcm)1, but the correct SI units are Siemenm.congruent phases, nthose states of
25、 matter of unique com-position that co-exist at equilibrium at a single point intemperature and pressure; for example, the two coexistingphases of a two-phase equilibrium. E7congruent transformation, nan isothermal, or isobaric,phase change in which both of the phases concerned have thesame composit
26、ion throughout the process; the order of asystem becomes unary at a composition of congruency. E7constitutional diagram, ngraphical representation of thecompositions, temperatures, pressures, or combinationsthereof at which the heterogeneous equilibria of a systemoccur.cooling curve, ngraphical repr
27、esentation of specimen tem-perature or temperature change as a function of time ordecreasing environment temperature.cooling rate, naverage slope of the time-temperature curvetaken over a specific time and temperature interval as thetemperature is decreased.critical curve, nin a binary, or higher or
28、der, phase diagram,a locus of points along which two or more phases exist instable thermodynamic equilibrium.critical point, nin a binary phase diagram, that specific valueof composition, temperature, pressure, or combinationsthereof at which the phases of a heterogeneous equilibriumbecome identical
29、.critical pressure, nthat pressure at the critical point.critical surface, nin a ternary or higher order phase diagram,the area upon which the phases in equilibrium becomeidentical. E7critical temperature, nthat temperature at the critical point.crystal, nsolid composed of atoms, ions, or molecules,
30、arranged in a pattern which is periodic in three dimensions.E7crystallinity, nregular arrangement of the atoms of a solid inspace.DISCUSSIONIn most materials, this state is usually imperfectlyachieved. The crystalline regions (ordered regions) are submicroscopicvolumes in which there is more or less
31、 regularity of arrangement of thecomponent molecules.crystallite, ncrystalline grain not bounded by habit planes.E7E1142 142crystallization, narrangement of previously disordered ma-terial segments of repeating patterns into geometric symme-try.crystallization temperature, nthat temperature at which
32、 aspecimen undergoes crystallization upon cooling.Curie point, nsee Curie temperature.Curie temperature, ntemperature above which a ferromag-netic or ferroelectric material becomes paramagnetic, orparaelectric, respectively.DISCUSSIONThere may be more than one if there are multiplematerials.damping,
33、 nloss in energy, dissipated as heat, that resultswhen a material or material system is subjected to anoscillatory load or displacement. D4092devitrification, ncrystallization of an amorphous substance.E7dielectric constant, nsee permittivity, relative.dielectric dissipation factor, D, nthe ratio of
34、 the loss factor,“, to the absolute permittivity, , or:D 5 “/ (2)DISCUSSIONThe dielectric dissipation factor is numerically equal tothe tangent of the dielectric loss angle and may be referred to as the losstangent, tan , or the cotangent of the phase angle, .dielectric loss angle, nthe angle whose
35、tangent is thedissipation factor or arctan “/.DISCUSSIONIt is also the difference between 90 degrees and thephase angle.differential thermocouple, nsee differential thermopile.differential thermopile, na number of temperature sensorsconnected in series-opposing and arranged so that there is anincrea
36、se in output signal for a given temperature differencebetween alternate junctions maintained at a reference tem-perature and the measured temperature.dilatancy, nthe increase in volume caused by shear.dipole relaxation time, , nthe exponential decay timerequired for the electric polarization of any
37、point of asuitably charged dielectric to fall from its original value to1/e of that value, due to the loss of dipole orientation.DISCUSSIONUnder conditions of an alternating applied field and insystems with a single dipole relaxation time, it is equal to 1/ at the lossfactor peak in cases where the
38、peak is caused by a dipole mechanism.dissipation factor, nsee tangent delta.dissociation, nas applied to heterogeneous equilibria, thetransformation of one phase into two or more new phases, allof different composition. E7dynamic modulus, nsee complex modulus.elasticity, nthat property of materials
39、that causes them toreturn to their original form or condition after the appliedforce is removed. D4092elastic modulus, nsee complex modulus and storage modu-lus.enthalpy, na thermodynamic function defined by the equa-tion H = U + PV where H is the enthalpy, U is the internalenergy, P is the pressure
40、, and V the volume of the system.DISCUSSIONAt constant pressure the change in enthalpy measuresthe quantity of heat exchanged by the system and its surrounding.equilibrium diagram, nsee constitutional diagram.eutectic point, nsee eutectic.eutectic, adjmixture of two or more substances whichsolidifie
41、s as a whole when cooled from the liquid state,without change in composition.DISCUSSIONThe temperature at which the eutectic mixture solidifiesis called the eutectic point. This temperature is constant for a givencomposition, and represents the lowest melting point of the system.expansivity, nthe ch
42、ange in dimension resulting from aninfinitesimal change in an independent variable (such astemperature or humidity).failure, nthe point beyond which a material ceases to befunctionally capable of its intended use.failure temperature (Tf), nthe temperature at which amaterial fails.Fahrenheit, ndesign
43、ation of a degree on the Fahrenheittemperature scale that is related to the International PracticalTemperature Scale by means of the equation: TF= 1.8 TC+ 32.where:TFis the temperature in degree Fahrenheit and TCis thetemperature in degrees Celsius.freezing temperature, nsee crystallization temperat
44、ure.frequency, f, nthe number of cycles per unit time of periodicprocess.DISCUSSIONThe unit is Hertz (Hz) which is equal to 1 cycle per/s.frequency profile, nin dynamic mechanical measurement,plot of the dynamic properties of a material, at a constanttemperature, as a function of test frequency. D40
45、92gage pressure, npressure measured relative to atmosphericpressure.DISCUSSIONGage pressure is the difference between absolute pres-sure and atmospheric pressure.gamma () loss peak, nin dynamic mechanicalmeasurement, third peak in the damping curve below themelt, in the order of decreasing temperatu
46、re or increasingfrequency. D4092Gibbs Phase Rule, nmaximum number of phases (P) thatmay coexist at equilibrium is equal to two, plus the numberof components (C) in the mixture, minus the number ofdegrees of freedom (F): P+F=C+2. E7glass transition, nreversible change in an amorphous mate-rial or in
47、amorphous regions of a partially crystallinematerial, from (or to) a viscous or rubbery condition to (orfrom) a hard and relatively brittle one.DISCUSSIONThe glass transition generally occurs over a relativelynarrow temperature region and is similar to the solidification of a liquidE1142 143to a gla
48、ssy state. Not only do hardness and brittleness undergo rapidchanges in this temperature region, but other properties, such ascoefficient of thermal expansion and specific heat capacity, also changerapidly. This phenomenon sometimes is referred to as a second ordertransition, rubber transition, or r
49、ubbery transition. When more than oneamorphous transition occurs in a material, the one associated withsegmental motions of the backbone molecular chain, or accompaniedby the largest change in properties is usually considered to be the glasstransition.glass transition temperature, na temperature chosen torepresent the temperature range over which the glass transi-tion takes place.DISCUSSIONThe glass transition temperature can
