ASTM E1142-97
(Terminology)Standard Terminology Relating to Thermophysical Properties
Standard Terminology Relating to Thermophysical Properties
SCOPE
1.1 This is a compilation of terms and corresponding definitions commonly used in the study of thermophysical properties. Terms that are generally understood or defined adequately in other readily available sources are either not included or their sources identified.
1.2 A definition is a single sentence with additional information included in a Discussion . It is reviewed every five years, and the year of the last review or revision is appended.
1.3 Definitions identical to those published by another standards organization or ASTM Committee are identified with the abbreviation of the name of the organization or the identifying document and ASTM Committee; for example, ICTA is the International Confederation for Thermal Analysis.
1.4 Definitions of terms specific to a particular field (such as dynamic mechanical measurements ) are identified with an italicized introductory phrase.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1142 – 97
Standard Terminology
Relating to Thermophysical Properties
This standard is issued under the fixed designation E 1142; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope traversed by a rotating vector that represents any periodically
varying quantity.
1.1 This is a compilation of terms and corresponding
definitions commonly used in the study of thermophysical
DISCUSSION—Angular frequency, v, is equal to two p times the
properties. Terms that are generally understood or defined frequency, f.
adequately in other readily available sources are either not
arrhenius equation—a mathematical relationship between the
included or their sources identified.
specific reaction rate and the temperature given as
1.2 A definition is a single sentence with additional infor-
–E/RT
mation included in a Discussion. It is reviewed every five k 5 Ae (1)
years, and the year of the last review or revision is appended.
where:
1.3 Definitions identical to those published by another
k is the reaction rate constant, A is the frequency factor, E is the
standards organization or ASTM Committee are identified with
energy of activation, R is the gas constant, and T is the absolute
the abbreviation of the name of the organization or the
temperature, (1990).
identifying document and ASTM Committee; for example,
beta (b) loss peak—in dynamic mechanical measurement,
ICTA is the International Confederation for Thermal Analysis.
second discrete peak in damping curve below the melt, in
1.4 Definitions of terms specific to a particular field (such as
order of decreasing temperature or increasing frequency,
dynamic mechanical measurements) are identified with an
(D 4092, D-20), (1988).
italicized introductory phrase.
boiling pressure—at a specific temperature, the value of the
vapor pressure of the liquid at which it is equal to the
2. Referenced Documents
external pressure, (1988).
2.1 ASTM Standards:
boiling temperature—at a specific pressure, the temperature
D 2160 Test Method for Thermal Stability of Hydraulic
at which the vapor pressure of the liquid is equal to the
Fluids
external pressure, (1988).
D 4092 Terminology Relating to Dynamic Mechanical
capacitance—that property of a system of conductors and
Measurements on Plastics
dielectrics that permits the storage of electrical charge when
E 7 Terminology Relating to Metallography
a potential difference exists between the conductors.
E 473 Terminology Relating to Thermal Analysis
DISCUSSION—Capacitance is the ratio of a quantity of electric charge,
Q, to a potential difference, V. A capacitance value is always positive.
3. Terminology
The unit of capacitance is the farad, F, which is equivalent to one
3.1 Terms and Definitions:
coulomb per volt.
admittance, Y— the reciprocal of impedance.
Celsius—designation of the degree on the International Prac-
alpha (a) loss peak—in dynamic mechanical measurement,
tical Temperature Scale; also used for the name of the scale,
first peak in the damping curve below the melt, in order of
as “Celsius Temperature Scale.” Formerly (prior to 1948)
decreasing temperature or increasing frequency, (D 4092,
called“ Centigrade.” The Celsius temperature scale is related
D-20), (1988).
to the International Kelvin Temperature Scale by the equa-
angular frequency, v—the number of radians per second
tion T 5 T − 273.16K, (1988).
c
Centigrade—see Celsius.
coeffıcient of expansion— see coefficient of linear thermal
This terminology is under the jurisdiction of ASTM Committee E-37 on
Thermal Measurements and are the direct responsibility of Subcommittee E37.03 on
expansion.
Nomenclature and Definitions.
coefficient of linear thermal expansion, a —change in
l
Current edition approved August 10, 1997. Published March 1998. Originally
length, relative to the length of the specimen, accompanying
published as E 1142 – 88. Last previous edition E 1142 – 96.
Annual Book of ASTM Standards, Vol 05.01. a unit change of temperature, at a specified temperature,
Annual Book of ASTM Standards, Vol 08.02.
(1988).
Annual Book of ASTM Standards, Vol 03.01.
coefficient of volume thermal expansion a —for a solid or
v
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1142
liquid, the change in volume, relative to the volume of the stable thermodynamic equilibrium.
specimen, accompanying a change of temperature at a critical point—in a binary phase diagram, that specific value
specified temperature, (1988).
of composition, temperature, pressure, or combinations
color temperature—temperature in degrees Kelvin (K) at thereof at which the phases of a heterogeneous equilibrium
which a black body must be operated to give a color equal to
become identical, (1989).
that of the source in question, (1988). critical pressure—that pressure at the critical point; (1990).
complex modulus, E*, G*, or K*—ratio of the stress to strain
critical surface—in a ternary or higher order phase diagram,
where each is a factor that may be represented by a complex the area upon which the phases in equilibrium become
number as follows: E* 5 E8+iE9,G* 5 G8+iG9, and
identical, (E 7, E-4), (1988).
K* 5 K8+iK9.
critical temperature—that temperature at the critical point,
where: (1990).
E* 5 complex modulus, measured in tension or flexure,
crystal—solid composed of atoms, ions, or molecules, ar-
E8 5 storage modulus, measured in tension or flexure,
ranged in a pattern which is periodic in three dimensions,
E9 5 loss modulus, measured in tension or flexure,
(E 7, E-4), (1988).
G* 5 complex modulus, measured in shear,
crystallinity—regular arrangement of the atoms of a solid in
G8 5 storage modulus, measured in shear,
space, (1988).
G9 5 loss modulus, measured in shear,
DISCUSSION—In most materials, this state is usually imperfectly
K* 5 complex modulus, measured in compression,
achieved. The crystalline regions (ordered regions) are submicroscopic
K8 5 storage modulus, measured in compression
K9 5 loss modulus, measured in compression, and volumes in which there is more or less regularity of arrangement of the
i 5 –1 , measured in compression.
= component molecules.
The complex modulus may be measured in tension or
crystallite—crystalline grain not bounded by habit planes,
flexure, (E*), compression, (K*), or in shear, (G*), (D 4092,
(E 7, E-4), (1988).
D-20), (1988).
crystallization—arrangement of previously disordered mate-
complex shear compliance, J*—reciprocal of complex shear
rial segments of repeating patterns into geometric symmetry,
modulus, where J* 5 1/G*, (D 4092, D-20), (1988).
(1988).
complex tensile compliance, D*—reciprocal of complex ten-
crystallization temperature—that temperature at which a
sile modulus, where D* 5 1/E*, (D 4092, D-20), (1988).
specimen undergoes crystallization upon cooling, (1988).
composition—quantity of the components of a mixture; usu-
Curie point—see Curie temperature.
ally expressed in terms of the weight percentage, or the
Curie temperature—temperature above which a ferromag-
atomic percentage of each of the components in the mixture,
netic or ferroelectric material becomes paramagnetic, or
(E 7, E-4), (1988).
paraelectric, respectively (1997).
conductivity, electrical (volume), s— the ratio of the current
−2 DISCUSSION—There may be more than one if there are multiple
density (A·cm ) through a specimen to the potential
materials.
gradient ( V/cm) in the same direction as the current.
damping—loss in energy, dissipated as heat, that results when
DISCUSSION—Conductivity is normally expressed in units (ohm·cm)
a material or material system is subjected to an oscillatory
−1, but the correct SI units are Siemen·m.
load or displacement, (D 4092, D-20), (1988).
congruent phases—those states of matter of unique composi-
devitrification—crystallization of an amorphous substance,
tion that co-exist at equilibrium at a single point in tempera-
(E 7, E-4), (1988).
ture and pressure; for example, the two coexisting phases of
dielectric constant— see permittivity, relative.
a two-phase equilibrium (E 7, E-4), (1988).
dielectric dissipation factor, D—the ratio of the loss factor, e9,
congruent transformation—an isothermal, or isobaric, phase
to the absolute permittivity, e8,or
change in which both of the phases concerned have the same
D 5e9/e8 (2)
composition throughout the process; the order of a system
DISCUSSION—The dielectric dissipation factor is numerically equal to
becomes unary at a composition of congruency, (E 7, E-4),
the tangent of the dielectric loss angle and may be referred to as the loss
(1988).
tangent, tan d, or the cotangent of the phase angle, u.
constitutional diagram—graphical representation of the com-
positions, temperatures, pressures, or combinations thereof
dielectric loss angle—the angle whose tangent is the dissipa-
at which the heterogeneous equilibria of a system occur,
tion factor or arctan e9/e8.
(1988).
DISCUSSION—It is also the difference between 90 degrees and the
cooling curve—graphical representation of specimen tempera-
phase angle.
ture or temperature change as a function of time or decreas-
ing environment temperature, (1988).
differential thermocouple— see differential thermopile.
cooling rate—average slope of the time-temperature curve differential thermopile—a number of temperature sensors
taken over a specific time and temperature interval as the
connected in series-opposing and arranged so that there is an
temperature is decreased, (1988). increase in output signal for a given temperature difference
critical curve—in a binary, or higher order, phase diagram, a between alternate junctions maintained at a reference tem-
locus of points along which two or more phases exist in perature and the measured temperature, (1989).
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1142
dipole relaxation time, g—the exponential decay time re- hard and relatively brittle one, (1988).
quired for the electric polarization of any point of a suitably
DISCUSSION—The glass transition generally occurs over a relatively
charged dielectric to fall from its original value to 1/e of that
narrow temperature region and is similar to the solidification of a liquid
value, due to the loss of dipole orientation.
to a glassy state. Not only do hardness and brittleness undergo rapid
changes in this temperature region, but other properties, such as
DISCUSSION—Under conditions of an alternating applied field and in
coefficient of thermal expansion and specific heat capacity, also change
systems with a single dipole relaxation time, it is equal to 1/v at the loss
rapidly. This phenomenon sometimes is referred to as a second order
factor peak in cases where the peak is caused by a dipole mechanism.
transition, rubber transition, or rubbery transition. When more than one
amorphous transition occurs in a material, the one associated with
dissipation factor— see tangent delta.
segmental motions of the backbone molecular chain, or accompanied
dissociation—as applied to heterogeneous equilibria, the
by the largest change in properties is usually considered to be the glass
transformation of one phase into two or more new phases, all
transition.
of different composition, (E 7, E-4), (1988).
dynamic modulus—see complex modulus. glass transition temperature—a temperature chosen to rep-
elasticity—that property of materials that causes them to return resent the temperature range over which the glass transition
to their original form or condition after the applied force is takes place, (1989).
removed, (D 4092, D-20), (1988).
DISCUSSION—The glass transition temperature can be determined
elastic modulus—see complex modulus and storage modu-
readily by observing the temperature region at which a significant
lus.
change takes place in some specific electrical, mechanical, thermal, or
enthalpy—a thermodynamic function defined by the equation other physical property. Moreover, the observed temperature can vary
significantly depending on the property chosen for observation and on
H 5 U + PV where H is the enthalpy, U is the internal
details of the experimental technique (for example, heating rate,
energy, P is the pressure, and V the volume of the system.
frequency of test). Therefore, the observed Tg should be considered
DISCUSSION—At constant pressure the change in enthalpy measures
valid only for that particular technique and set of test conditions.
the quantity of heat exchanged by the system and its surrounding.
heat capacity—quantity of heat necessary to change the
equilibrium diagram— see constitutional diagram.
temperature of an entity, substance or system by one Kelvin
eutectic point—see eutectic.
of temperature.
eutectic—mixture of two or more substances which solidifies
DISCUSSION—The SI units of measurement are J/K (1995).
as a whole when cooled from the liquid state, without change
in composition, (1988).
impedance, Z—the ratio of the time dependent voltage, v (t),
across a circuit, a circuit element, or material to the time
DISCUSSION—The temperature at which the eutectic mixture solidifies
dependent current, i (t), through it; that is:
is called the eutectic point. This temperature is constant for a given
composition, and represents the lowest melting point of the system.
Z 5 v~t!/i~t! (3)
Fahrenheit—designation of a degree on the Fahrenheit tem-
DISCUSSION—The impedance of a circuit, circuit element, or material
perature scale that is related to the International Practical
is a measure of its ability to oppose the transmission of an alternating
Temperature Scale by means of the equation: T 5 1.8 current. It is expressed in ohms. Its value depends on the angular
F
frequency, v, of the measurement.
T + 32.
C
where:
invariant equilibrium—stable state among a number of
T is the temperature in degree Fahrenheit and T is the
F C
phases exceeding by two the number of components in the
temperature in degrees Celsius, (1988).
system and in which more of the external variables (pres-
freezing temperature— see crystallization temperature.
sure, temperatures, or concentrations) may be varied without
frequency, f—the number of cycles per unit time of periodic
causing a decrease in the number of ph
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