1、Designation:D 3799 95Standard Test Method forPurity of Styrene by Freezing Point Method1This standard is issued under the fixed designation D 3799;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
2、parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method is used for determining the purity ofstyrene expressed as weight percent.All impurities are consid-ered to be ethylbenzene.1.2 The
3、following applies to all specified limits in thisstandard:for purposes of determining conformance with thisstandard,an observed value or a calculated value shall berounded off“to the nearest unit”in the last right-hand digitused in expressing the specification limit,in accordance withthe rounding-of
4、f method of Practice E 29.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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 sta
5、ndard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific hazardstatements are given in Section 5 and 6.5.2.Referenced Documents2.1 ASTM Standards:D 1015 Test Method for Freezing Points of High-PurityHydrocarbons2D 10
6、16 Test Method for Purity of Hydrocarbons fromFreezing Points2D 1193 Specification for Reagent Water3D 3437 Practice for Sampling and Handling Liquid CyclicProducts4E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications52.2Other Document:OSHA Regulations,
7、29 CFR,paragraphs 1910.1000 and1910.120063.Summary of Test Method3.1 The purity of the styrene is determined by a measure-ment of the freezing point of the sample in equilibrium with airat atmospheric pressure.The presence of small amounts ofimpurities causes a depression of the freezing point which
8、 isproportional to the molal concentration of the contaminatingsubstances.The freezing point is the highest temperatureobtained after the supercooling of the liquid.For purities over99%it is not necessary to plot a time-temperature curve.3.2 The freezing point methods,Test Methods D 1015 andD 1016,s
9、pecified a platinum resistance thermometer for mea-suring the temperature.For routine work,mercury-in-glassthermometers are used.Other temperature-measuring devicescan be utilized in this method provided that they havetemperature resolution to 0.01C or better.They must becalibrated since small diffe
10、rences in the temperature readingsare significant.They must be recalibrated about once per weekto correct for differences which may develop with age andhandling.To simplify the multiple calibrations the freezingpoint of a large sample of styrene is determined with aplatinum resistance thermometer an
11、d the mercury-in-glass orother thermometers calibrated against the standard styrene.Styrene may be kept in a deep freeze for several months withno appreciable change in the freezing point.4.Significance and Use4.1 Purity can be calculated by measuring the freezing pointand relating to a freezing poi
12、nt for zero impurities.4.2 This test method is in wide use for both producer andconsumer for determining purity and is suitable for establishingspecifications.4.3 All impurities are considered to be ethylbenzene.5.Apparatus5.1 Temperature-MeasuringDevicesTemperature-measuring devices can be used,pro
13、vided they have tempera-ture resolution to 0.01C or better,are operable in the rangefrom 20 to 40C,and are calibrated against a platinumresistance thermometer.5.2 Styrene Freezing Point Thermometer7Special designfor determination of the freezing point of styrene as shown inFig.1 and described in Tab
14、le 1 specification.1This test method is under the jurisdiction of ASTM Committee D-16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.0H on Styrene,Ethylbenzene,and C9and C10AromaticHydrocarbons.Current edition approved April 15,1995.Published June 1
15、995.Originallypublished as D 3799 79.Last previous edition D 3799 89(1993).2Annual Book of ASTM Standards,Vol 05.01.3Annual Book of ASTM Standards,Vol 11.01.4Annual Book of ASTM Standards,Vol 06.04.5Annual Book of ASTM Standards,Vol 14.02.6Available from Superintendent of Documents,U.S.Government Pr
16、intingOffice,Washington,DC 20402.7A thermometer meeting the specification is manufactured by the PrecisionThermometer and Instrument Co.,Southhampton Industrial Park,Southhampton,PA 18966,catalog No.0230(range:33C to 30C).An equivalent may be used.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTM5.3 Freezing Point ApparatusSee Fig.2 which consists ofa 665-mL Dewar flask of borosilicate glass,a