ASTM_E_1142_-_15.pdf

Designation:E114215Standard 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 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 correspondingdefinitions commonly used in the study of thermophysicalproperties.Terms that are generally understood 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.1.3 Definitions of terms specific to a particular field(such asdynamic mechanical measurements)are identified 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-etryE2744 Test Method for Pressure Calibration of ThermalAnalyzers3.Terminology3.1 Definitions:absolute pressure,npressure 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 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 order ofdecreasing temperature or increasing frequency.E7amorphicity,na relative measure of amorphous materialcontent,expressed as a percent of the total material content.angular 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 for 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 constant and the temperature givenas:k 5 Ae2E/RT(1)where:k=the reaction rate constant,A=the pre-exponential factor,E=the energy of activation,R=the gas constant,andT=the absolute temperature.atmospheric pressure,nthe pressure due to the weight ofthe atmosphere.E2744DISCUSSIONAtmospheric pressure varies with elevation above sealevel,acceleration due to gravity,and weather conditions.barometer,nan instrument for measuring atmospheric pres-sure.beta()loss peak,nin dynamic mechanical measurement,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.1This terminology is under the jurisdiction of ASTM Committee E37 onThermal Measurements and are the direct responsibility of Subcommittee E37.03 onNomenclature and Definitions.Current edition approved May 1,2015.Published June 2015.Originallyapproved in 1988.Last previous edition approved in 2014 as E1142 14b.DOI:10.1520/E1142-15.2For 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 Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 boiling temperature,nat a specific pressure,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.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 capacitance is the farad,F,which is equivalent to onecoulomb per volt.catalyst,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“Centigrade.”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.co