1、Designation:D79213Standard Test Methods forDensity and Specific Gravity(Relative Density)of Plasticsby Displacement1This standard is issued under the fixed designation D792;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope*1.1 These test methods describe the determina
3、tion of thespecific gravity(relative density)and density of solid plasticsin forms such as sheets,rods,tubes,or molded items.1.2 Two test methods are described:1.2.1 Test Method AFor testing solid plastics in water,and1.2.2 Test Method BFor testing solid plastics in liquidsother than water.1.3 The v
4、alues stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bilit
5、y of regulatory limitations prior to use.NOTE1This standard is not equivalent to ISO 11831 MethodA.Thistest method provides more guidelines on sample weight and dimension.ISO 1183-1 allows testing at an additional temperature of 27 6 2C.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Con
6、ditioning Plastics for TestingD891 Test Methods for Specific Gravity,Apparent,of LiquidIndustrial ChemicalsD4968 Guide for Annual Review of Test Methods andSpecifications for PlasticsD6436 Guide for Reporting Properties for Plastics andThermoplastic ElastomersE1 Specification for ASTM Liquid-in-Glas
7、s ThermometersE12 Terminology Relating to Density and Specific Gravityof Solids,Liquids,and Gases(Withdrawn 1996)3E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI-10 Practice for Use of the InternationalSystem of Units(SI)(the Modernized Me
8、tric System)3.Terminology3.1 GeneralThe units,symbols,and abbreviations used inthese test methods are in accordance with IEEE/ASTM SI-10.3.2 Definitions:3.2.1 specific gravity(relative density)the ratio of themass of a given volume of the impermeable portion of thematerial at 23C to the mass of an e
9、qual volume of gas-freedistilled or de-mineralized water at the same temperature;theform of expression shall be:Specific gravityrelative density!23/23Cor sp gr23/23C!NOTE2This definition is essentially equivalent to the definition forapparent specific gravity and apparent density in Terminology E12,
10、because the small percentage difference introduced by not correcting forthe buoyancy of air is insignificant for most purposes.3.2.2 densitycubic metre of impermeable portion of thematerial at 23C.The form of expression shall be:D23,kg/m3NOTE3The SI unit of density,as defined in IEEE/ASTM SI-10,iskg
11、/m3.To convert density in g/cm3to density in kg/m3,multiply by 1000.NOTE4To convert specific gravity 23/23C to density 23C,kg/m3,use the following equation:D23 C,kg/m35 sp gr23/23C 3997.5Where 997.5 kg/m3is the density of water at 23C.4.Summary of Test Method4.1 Determine the mass of a specimen of t
12、he solid plastic inair.It is then immersed in a liquid,its apparent mass uponimmersion is determined,and its specific gravity(relativedensity)calculated.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.70 on Analyti
13、calMethods(Section D20.70.01).Current edition approved Nov.1,2013.Published November 2013.Originallyapproved in 1944.Last previous edition approved in 2008 as D792-08.DOI:10.1520/D0792-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceast
14、m.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,
15、100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 The specific gravity or density of a solid is a propertythat is conveniently measured to identify a material,to followphysical changes in a sample,to indicate degree of uniformityamong differen
16、t sampling units or specimens,or to indicate theaverage density of a large item.5.2 Changes in density of a single material are due tolocalized differences in crystallinity,loss of plasticizer,absorp-tion of solvent,or to other causes.It is possible that portions ofa sample differ in density because of their differences incrystallinity,thermal history,porosity,and composition(typesor proportions of resin,plasticizer,pigment,or filler).5.3 Density is useful for calculating strength-weight andcost
