1、Designation: E1142 12E1142 13Standard 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 i
2、n 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 u
3、nderstood 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. It is reviewed every five years, andthe year of the last review or revision is appended.1.
4、3 Definitions identical to those published by another standards organization or ASTM Committee are identified with theabbreviation of the name of the organization or the identifying document and ASTM Committee.1.4 Definitions of terms specific to a particular field (such as dynamic mechanical measur
5、ements) 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 Hydrometry3. Terminology3.1 Definitions:absolute p
6、ressure, npessurepressure 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 order for a chemical reaction to occur.DISCUSSIONThe term
7、 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 dynamic mechanical measurement, first peak in the damping cur
8、ve below the melt, in order ofdecreasing temperature or increasing frequency. E7angular frequency, , nthe number of radians per second traversed by a rotating vector that represents any periodically varyingquantity.1 This terminology is under the jurisdiction of ASTM Committee E37 on Thermal Measure
9、ments and are the direct responsibility of Subcommittee E37.03 onNomenclature and Definitions.Current edition approved Sept. 1, 2012March 1, 2013. Published October 2012May 2013. Originally approved in 1988. Last previous edition approved in 20112012 asE1142 11b.E1142 12. DOI: 10.1520/E1142-12.10.15
10、20/E1142-13.2 For referencedASTM standards, visit 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 inte
11、nded only to provide the user of an ASTM standard 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 curre
12、nt versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1DISCUSSIONAngular frequency, , is equal to two pi times the frequency, f.anisotropic, adjhaving d
13、ifferent values for a property in different directions.anti-thixotropy, nan increase of the apparent viscosity under constant 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 specifi
14、c reaction rate and the temperature given as:k 5Ae2E/RT (1)where:k is the reaction rate constant, A is the frequency factor, E is the energy of activation, R is the gas constant, and T is the abso-lute temperature.barometer, nAn instrument for measuring atmospheric pressure.beta () loss peak, nin dy
15、namic 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 of the vapor pressure of the liquid at which it is equal to the externalpressure.boiling tempera
16、ture, 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 the storage of electrical charge when apotential difference exists between the conductors.DISCU
17、SSIONCapacitance 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 coulomb per volt.catalyst, na substance that increases the rate of a chemical reaction but is no
18、t 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 (prior to 1948) called “Centigrade.” The Celsius temperature scale is related to theInternational
19、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 length, relative to the length of the specimen, accompanying a unitchange of temperature, at a
20、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 solid or liquid, the change in volume, relative to the volume of the specimen,accompanying a ch
21、ange 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*, or K*,nratio of the stress to strain where each is a factor that may be represented by a comp
22、lexnumber 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, measured in shear,G = storage modulus, measured in
23、 shear,G9 = loss modulus, measured in shear,K* = complex modulus, measured in compression,E1142 132K = storage modulus, measured in compressionK9 = loss modulus, measured in compression, andi 521 , measured in compression.The complex modulus may be measured in tension or flexure, (E*), compression,
24、(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* = 1/E*. D4092complex viscosity, *, nthe complex modulus divided by the imposed frequency in rad/plian
25、ce, 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 the atomicpercentage of each of the components in the mixture. E7conductivity, electrical (volum
26、e), , 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 the correct SI units are Siemenm.congruent phases, nthose states of matter of unique composition
27、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 change in which both of the phases concerned have the samecomposition throughout the process; t
28、he 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 heterogeneous equilibria of a system occur.cooling curve, ngraphical representation of specimen tem
29、perature 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 the temperatureis decreased.critical curve, nin a binary, or higher order, phase diagram, a locu
30、s 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 thereof atwhich the phases of a heterogeneous equilibrium become identical.critical pressure, nth
31、at 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 the critical point.crystal, nsolid composed of atoms, ions, or molecules, arranged in a pattern
32、 which is periodic in three dimensions. E7crystallinity, nregular arrangement of the atoms of a solid in space.DISCUSSIONIn most materials, this state is usually imperfectly achieved. The crystalline regions (ordered regions) are submicroscopic volumes in which there ismore or less regularity of arr
33、angement of the component molecules.crystallite, ncrystalline grain not bounded by habit planes. E7crystallization, narrangement of previously disordered material segments of repeating patterns into geometric symmetry.crystallization temperature, nthat temperature at which a specimen undergoes cryst
34、allization upon cooling.E1142 133Curie point,nsee Curie temperature.Curie temperature, ntemperature above which a ferromagnetic or ferroelectric material becomes paramagnetic, or paraelectric,respectively.DISCUSSIONThere may be more than one if there are multiple materials.damping, nloss in energy,
35、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 constant,nsee permittivity, relative.dielectric dissipation factor, D,nthe ratio of the loss factor,
36、“, 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 , or thecotangent of the phase angle, .dielectric loss angle, nthe angle whose tangent is the di
37、ssipation 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 temperature sensors connected in series-opposing and arranged so that there is an increasein output si
38、gnal 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 time, , nthe exponential decay time required for the electric polarization of any point of a suit
39、ably 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 dipole relaxation time, it is equal to 1/ at the loss factor peak in caseswhere the peak is cause
40、d 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 composition. E7dynamic modulus,nsee complex modulus.elasticity, nthat property of materials that causes th
41、em to return to their original form or condition after the applied force isremoved. D4092elastic modulus,nsee complex modulus and storage modulus.enthalpy, na thermodynamic function defined by the equation H = U + PV where H is the enthalpy, U is the internal energy,P is the pressure, and V the volu
42、me 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.E1142 134eutectic point,nsee eutectic.eutectic, adjmixture of two or more substances which solidifies as a
43、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 given composition, and representsthe lowest melting point of the system.expansivity, nthe change i
44、n 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 use.failure temperature (Tf), nthe temperature at which a material fails.Fahrenheit, ndesignati
45、on of a degree on the Fahrenheit temperature scale that is related to the International PracticalTemperature Scale by means of the equation: TF = 1.8 TC + 32.where:TF is the temperature in degree Fahrenheit and TC is the temperature in degrees Celsius.freezing temperature,nsee crystallization temper
46、ature.frequency, f, nthe 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.
47、 D4092gage pressure, npressure 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 temp
48、erature or increasing frequency. D4092Gibbs Phase Rule, nmaximum number of phases (P) that may coexist at equilibrium is equal to two, plus the number ofcomponents (C) in the mixture, minus the number of degrees of freedom (F): P + F = C + 2. E7glass transition, nreversible change in an amorphous ma
49、terial or in amorphous regions of a partially crystalline material, from(or to) a viscous or rubbery condition to (or from) a hard and relatively brittle one.DISCUSSIONThe glass transition generally occurs over a relatively narrow temperature region and is similar to the solidification of a liquid to a glassy state. Notonly do hardness and brittleness undergo rapid changes in this temperature region, but other properties,
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