1、 i ASTM D2870 86 m 0759530 0070399 3 m-Designation:D 2870-86(Reapproved 1990)Standard Test Method for Gel Time of Tar Acids This standard is issued under the fixed designation D 2870;the number immediately following the designation indicates the year of original adoption or,in the case of revision,t
2、he 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 1.1 This test method covers determination of the gel time of tar acids in the range from 8 to 120 min.1.2 This st
3、andard does not purport to address all o f the safety problems associated with its use.It is the responsibility o f whoever uses this standard to consult and establish appropriate safity and health practices and determine the applicability o f regulatory limitations prior to use.For specific hazard
4、statements,see Section 8.2.Referenced Documents 2.1 ASTM Standards:D2194 Test Method for Concentration of Formaldehyde D3852 Practice for Sampling and Handling Phenol and E 1 Specification for ASTM Thermometers3 2.2 Other Document:OSHA Regulations,29 CFR,paragraphs 19 10.1OOO and Solutions Cresylic
5、Acids 1910.12004 3.Definitions 3.1 gel time-the time required for the polymerization reaction to proceed to a point where the viscous drag on a rotating spindle,partially immersed in the reaction mass,is sufficient to overcome the torsional force exerted on the spindle by a constant speed drive asse
6、mbly,magnetically coupled to the spindle by a standard torsion spring.3.2 tar acid-phenol or its homologues either individualIy or blended together.4.Summary of Test Method 4.1 Observing specific conditions,an aliquot of the well-mixed specimen is blended with powdered paraformal-dehyde and triethan
7、olamine catalyst and the gel time deter-mined using an automatic gel time test meter.5.Significance and Use 5,l The gel time value is a measure of the reactivity of tar acids.As a quality control procedure it is one of the techniques employed to determine batch to batch unifor-I This test method is
8、under the jurisdiction of ASTM Committee D l 6 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee D16.K on Oxygenated Aromatics.Current edition approved Ocf.31,1986.Published December 1986.Originally published as D 2870-70 T.Last previous edition D 2870-8
9、2.Annttal Book o f ASTM Standards,Yo1 06.03.Annual Book ofASTM Standards,Vol 14.03.Available from Superintendenf of Documents,U.S.Government Printing Oflice,Washington,DC 20402.mity.The gel time test also serves as a means for studying the effects of reaction variables such as composition,tempera-tu
10、re and concentration.6.Apparatus of (Fig.1):6.1 Automatic gel time meter and accessories5 consisting 6.1.1 Constant-Temperature Bath.6.1.2 Bath Cover Plate with center opening to accommo-date a one-hole neoprene rubber stopper and test tube and with condensing coil and immersion heater attached.6.1.
11、3 Glass Spindle,165 by 6 mm equipped with a magnetic coupling assembly.6.1.4 Torsion Spring,44.5 by 0.25-mm piano wire.6.1.5 Lower Torsion Spring Vise with magnetic assembly.6.1.6 Upper Torsion Spring Vise with upper contact 6.1.7 Lower Contact.6.1.8 Feeler Gage,28.067 by 2.25 mm(1.105 by 3/32 in.).
12、6.1.9 Test Tube,18 by 150 mm,borosilicate glass.6.1.10 Variable Transformer.6.1.1 1 Ring Stand.6.1.12 Thermometer-An ASTM Partial Immersion Thermometer,having a range from 90 to 170C and con-forming to the requirements for Thermometer 35C as prescribed in Specification E 1.7.Reagents 7.1 Purity o f
13、Reagents-Reagent grade chemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chem-ical Society,where such specifications are available:Other grades may be used,provi
14、ded it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.assembly.7.2 Paraformaldehyde:7.2.1 The paraformaldehyde used for this test shall be a free-flowing powder,free of lumps,passing through a 100-mesh screen
15、.7.2.2 The formaldehyde content shall be 93 f 1%as determined by assay,according to the procedure outlined in Test Method D 2194,with the following exceptions:5Gel time meter available from Sunshine Scientific Instrument,Inc.,1810 Grant Ave,Philadelphia,PA 191 IS,or its equivalent has been found sat
16、isfactory for this purpose.“Reagent Chemicals,American Chemical Society Specifications,”Am.Chem-the American Chemical Society,see“Reagent Chemicals and Standards,”by ical Soc.,Washington,DC.For suggestions on the testing of reagents not listed by Joseph Rosin,D.Van Nostrand Co.,Inc.,New York,NY,and the“United Stata Pharmacopeia.”629 NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.ASTM
