1、Designation: E1142 14aE1142 14bStandard 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
2、 in parentheses 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 corresponding definitions commonly used in the study of thermophysical properties.Terms that are generally
3、 understood or defined adequately in other readily available sources are either not included or their sourcesidentified.1.2 A definition is a single sentence with additional information included in a Discussion.1.3 Definitions of terms specific to a particular field (such as dynamic mechanical measu
4、rements) are identified with anitalicized introductory phrase.2. Referenced Documents2.1 ASTM Standards:2D4092 Terminology for Plastics: Dynamic Mechanical PropertiesE7 Terminology Relating to MetallographyE344 Terminology Relating to Thermometry and HydrometryE2744 Test Method for Pressure Calibrat
5、ion of Thermal Analyzers3. Terminology3.1 Definitions:absolute pressure, npressure measured relative to zero pressure corresponding to empty space.DISCUSSIONAbsolute pressure is atmospheric pressure plus gage pressure.activation energy (E), nin chemical kinetics, the energy that must be overcome in
6、order for a chemical reaction to occur.DISCUSSIONThe term activation energy was introduced in 1889 by Svante Arrhenius as a mathematical term in the eponymous, empirical relationship betweentemperature and reaction rate constant.admittance, Y,nthe reciprocal of impedance.alpha () loss peak, nin dyna
7、mic mechanical measurement, first peak in the damping curve below the melt, in order ofdecreasing temperature or increasing frequency. E7amorphicity, na relative measure of amorphous material content, expressed as a percent of the total material content.angular frequency, , nthe number of radians pe
8、r second traversed by a rotating vector that represents any periodically varyingquantity.1 This terminology is under the jurisdiction of ASTM Committee E37 on Thermal Measurements and are the direct responsibility of Subcommittee E37.03 onNomenclature and Definitions.Current edition approved April 1
9、, 2014Aug. 15, 2014. Published April 2014September 2014. Originally approved in 1988. Last previous edition approved in 2014 asE1142 14.E1142 14a. DOI: 10.1520/E1142-14A.10.1520/E1142-14B.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at servicea
10、stm.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 an indication of what changes have been made to the previous version. Beca
11、useit 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 to be considered the official document.Copyright ASTM International, 100 B
12、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1DISCUSSIONAngular frequency, , is equal to two pi times the frequency, f.anisotropic, adjhaving different values for a property in different directions.anti-thixotropy, nan increase of the apparent viscosity under constan
13、t shear stress or shear rate followed by a gradual recoverywhen the stress or shear rate is reduced to zero.arrhenius equation, na mathematical relationship between the specific reaction rate constant and the temperature given as:k 5Ae2E/RT (1)where:kis the reaction rate constant, A is the frequency
14、pre-exponential factor, Eis the energy of activation, R is the gas constant, andTis the absolute temperature.atmospheric pressure, nthe pressure due to the weight of the atmosphere. E2744DISCUSSIONAtmospheric pressure varies with elevation above sea level, acceleration due to gravity, and weather co
15、nditions.barometer, nan instrument for measuring atmospheric pressure.beta () loss peak, nin dynamic mechanical measurement, second discrete peak in damping curve below the melt, in order ofdecreasing temperature or increasing frequency. D4092boiling pressure, nat a specific temperature, the value o
16、f the vapor pressure of the liquid at which it is equal to the externalpressure.boiling temperature, nat a specific pressure, the temperature at which the vapor pressure of the liquid is equal to the externalpressure.capacitance, nthat property of a system of conductors and dielectrics that permits
17、the storage of electrical charge when apotential difference exists between the conductors.DISCUSSIONCapacitance is the ratio of a quantity of electric charge, Q, to a potential difference, V. A capacitance value is always positive. The unit of capacitanceis the farad, F, which is equivalent to one c
18、oulomb per volt.catalyst, na substance that increases the rate of a chemical reaction but is not consumed or changed by that reaction.Celsius, ndesignation of the degree on the International Practical Temperature Scale; also used for the name of the scale, as“Celsius Temperature Scale.” Formerly (pr
19、ior to 1948) called “Centigrade.” The Celsius temperature scale is related to theInternational Kelvin Temperature Scale by the equation: Tc = T 273.16 K.Centigrade,nsee Celsius.coeffcient of expansion,nsee coefficient of linear thermal expansion.coefficient of linear thermal expansion, l,nchange in
20、length, relative to the length of the specimen, accompanying a unitchange of temperature, at a specified temperature.coefficient of viscosity, nthe ratio between an infinitesimally small increase in stress and the corresponding increase in strainrate.coefficient of volume thermal expansion v,nfor a
21、solid or liquid, the change in volume, relative to the volume of the specimen,accompanying a change of temperature at a specified temperature.color temperature, ntemperature in degrees Kelvin (K) at which a black body must be operated to give a color equal to thatof the source in plex modulus, E*,G*
22、, or K*,nratio of the stress to strain where each is a factor that may be represented by a complexnumber as follows: E* = E + iE“, G* = G + iG“, and K* = K + iK“.where:E* = complex modulus, measured in tension or flexure,E1142 14b2E = storage modulus, measured in tension or flexure,E9 = loss modulus
23、, measured in tension or flexure,G* = complex modulus, measured 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 , measur
24、ed in compression.The complex modulus may be measured in tension or flexure, (E*), compression, (K*), or in shear, (G*). D4092complex shear compliance, J*,nreciprocal of complex shear modulus, where J* = 1/G*. D4092complex tensile compliance, D*,nreciprocal of complex tensile modulus, where D* = 1E*
25、. D4092complex viscosity, *, nthe complex modulus divided by the imposed frequency in rad/pliance, J,nthe strain divided by the corresponding stress.DISCUSSIONCompliance is the reciprocal of position, nquantity of the components of a mixture; usually expressed in terms of the weight percentage, or t
26、he atomicpercentage of each of the components in the mixture. E7conductivity, electrical (volume), , nthe ratio of the current density (Acm2) through a specimen to the potential gradient(V/cm) in the same direction as the current.DISCUSSIONConductivity is normally expressed in units (ohmcm)1, but th
27、e correct SI units are Siemenm.congruent phases, nthose states of matter of unique composition that co-exist at equilibrium at a single point in temperatureand pressure; for example, the two coexisting phases of a two-phase equilibrium. E7congruent transformation, nan isothermal, or isobaric, phase
28、change in which both of the phases concerned have the samecomposition throughout the process; the order of a system becomes unary at a composition of congruency. E7constitutional diagram, ngraphical representation of the compositions, temperatures, pressures, or combinations thereof atwhich the hete
29、rogeneous equilibria of a system occur.cooling curve, ngraphical representation of specimen temperature or temperature change as a function of time or decreasingenvironment temperature.cooling rate, naverage slope of the time-temperature curve taken over a specific time and temperature interval as t
30、he temperatureis decreased.critical curve, nin a binary, or higher order, phase diagram, a locus of points along which two or more phases exist in stablethermodynamic equilibrium.critical point, nin a binary phase diagram, that specific value of composition, temperature, pressure, or combinations th
31、ereof atwhich the phases of a heterogeneous equilibrium become identical.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 become identical.E7critical temperature, nthat temperature at
32、the critical point.crystal, nsolid composed of atoms, ions, or molecules, arranged in a pattern which is periodic in three dimensions. E7crystallinity, nregular arrangement of the atoms of a solid in space.DISCUSSIONE1142 14b3In most materials, this state is usually imperfectly achieved. The crystal
33、line regions (ordered regions) are submicroscopic volumes in which there ismore or less regularity of arrangement of the component molecules.crystallite, ncrystalline grain not bounded by habit planes. E7crystallization, narrangement of previously disordered material segments of repeating patterns i
34、nto geometric symmetry.crystallization temperature, nthat temperature at which a specimen undergoes crystallization upon cooling.Curie point,nsee Curie temperature.Curie temperature, ntemperature above which a ferromagnetic or ferroelectric material becomes paramagnetic, or paraelectric,respectively
35、.DISCUSSIONThere may be more than one if there are multiple materials.damping, nloss in energy, dissipated as heat, that results when a material or material system is subjected to an oscillatory loador displacement. D4092devitrification, ncrystallization of an amorphous substance. E7dielectric const
36、ant,nsee permittivity, relative.dielectric dissipation factor, D,nthe ratio of the loss factor, “, to the absolute permittivity, , or:D 5“/ (2)DISCUSSIONThe dielectric dissipation factor is numerically equal to the tangent of the dielectric loss angle and may be referred to as the loss tangent, tan
37、, or thecotangent of the phase angle, .dielectric loss angle, nthe angle whose tangent is the dissipation factor or arctan “/.DISCUSSIONIt is also the difference between 90 degrees and the phase angle.differential thermocouple,nsee differential thermopile.differential thermopile, na number of temper
38、ature sensors connected in series-opposing and arranged so that there is an increasein output signal for a given temperature difference between alternate junctions maintained at a reference temperature and themeasured temperature.dilatancy, nthe increase in volume caused by shear.dipole relaxation t
39、ime, , nthe exponential decay time required for the electric polarization of any point of a suitably chargeddielectric to fall from its original value to 1/e of that value, due to the loss of dipole orientation.DISCUSSIONUnder conditions of an alternating applied field and in systems with a single d
40、ipole relaxation time, it is equal to 1/ at the loss factor peak in caseswhere the peak is caused by a dipole mechanism.dissipation factor,nsee tangent delta.dissociation, nas applied to heterogeneous equilibria, the transformation of one phase into two or more new phases, all ofdifferent compositio
41、n. E7dynamic modulus,nsee complex modulus.elasticity, nthat property of materials that causes them to return to their original form or condition after the applied force isremoved. D4092elastic limit, nthe greatest stress that can be applied to a material without permanent deformation.elastic modulus
42、, nthe ratio of stress to corresponding strain within the elastic limit of the stress-strain curve.E1142 14b4DISCUSSIONThe elastic modulus may also be measured in tension (E ), compression (K ), flexure (E ), or shear (G ). (See also complex modulus.)enthalpy, na thermodynamic function defined by th
43、e equation H = U + PV where H is the enthalpy, U is the internal energy,P is the pressure, and V the volume of the system.DISCUSSIONAt constant pressure the change in enthalpy measures the quantity of heat exchanged by the system and its surrounding.equilibrium diagram,nsee constitutional diagram.eu
44、tectic point,nsee eutectic.eutectic, adjmixture of two or more substances which solidifies as a whole when cooled from the liquid state, without changein composition.DISCUSSIONThe temperature at which the eutectic mixture solidifies is called the eutectic point. This temperature is constant for a gi
45、ven composition, and representsthe lowest melting point of the system.expansivity, nthe change in dimension resulting from an infinitesimal change in an independent variable (such as temperatureor humidity).failure, nthe point beyond which a material ceases to be functionally capable of its intended
46、 use.failure criterion, nspecification of the chemical, physical, mechanical, electrical, or other condition under which a materialceases to be functionally capable of its intended use.failure temperature (Tf), nthe temperature at which a material fails.Fahrenheit, ndesignation of a degree on the Fa
47、hrenheit temperature scale that is related to the International PracticalTemperature Scale by means of the equation:TF 51.8 TC132 (3)where:TF is the temperature in degree Fahrenheit and TC is the temperature in degrees Celsius.freezing temperature,nsee crystallization temperature.frequency, f, nthe
48、number of cycles per unit time of periodic process.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 constant temperature,as a function of test frequency. D4092gage pressure, npre
49、ssure measured relative to atmospheric pressure.DISCUSSIONGage pressure is the difference between absolute pressure and atmospheric pressure.gamma () loss peak, nin dynamic mechanical measurement, third peak in the damping curve below the melt, in the order ofdecreasing temperature or increasing frequency. D4092Gibbs Phase Rule, nmaximum number of phases (P) that may coexist at equilibrium is equal to two, plus th
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