1、AMERICAN NATIONAL STANDARDMETHOD FOR PREPARATIONOF A STANDARD MATERIALFOR DYNAMIC MECHANICALMEASUREMENTSAccredited Standards Committee S2, Mechanical Vibration and ShockStandards SecretariatAcoustical Society of America120 Wall Street, 32nd FloorNew York, New York 10005-3993ANSI S2.21-1998ANSIS2.21-
2、1998Reaffirmed by ANSI July 31, 2002 Reaffirmed by ANSI July 5, 2007 Reaffirmed by ANSI August 22, 2012 The American National Standards Institute, Inc. (ANSI) is the na-tional coordinator of voluntary standards development and the clear-inghouse in the U.S. for information on national and internatio
3、nalstandards.The Acoustical Society of America (ASA) is an organization of sci-entists and engineers formed in 1929 to increase and diffuse theknowledge of acoustics and to promote its practical applications.American National StandardMethod for Preparation of a Standard Materialfor Dynamic Mechanica
4、l MeasurementsSecretariatAcoustical Society of AmericaApproved 22 June 1998American National Standards Institute, Inc.AbstractThis Standard defines a method for preparing a standard viscoelastic material for comparison of differentinstruments and calibration of the same instrument.ANSI S2.21-1998AME
5、RICAN NATIONAL STANDARDS ON ACOUSTICSThe Acoustical Society of America (ASA) provides the Secretariat for AccreditedStandards Committees S1 on Acoustics, S2 on Mechanical Vibration and Shock,S3 on Bioacoustics, and S12 on Noise. These committees have wide represen-tation from the technical community
6、 (manufacturers, consumers, and general-interest representatives). The standards are published by the Acoustical Society ofAmerica through the American Institute of Physics as American National Stan-dards after approval by their respective standards committees and the AmericanNational Standards Inst
7、itute.These standards are developed and published as a public service to providestandards useful to the public, industry, and consumers, and to Federal, State,and local governments.Each of the Accredited Standards Committees operating in accordance with pro-cedures approved by American National Stan
8、dards Institute (ANSI) is responsiblefor developing, voting upon, and maintaining or revising its own standards. TheASA Standards Secretariat administers committee organization and activity andprovides liaison between the Accredited Standards Committees and ANSI. Afterthe standards have been produce
9、d and adopted by the Accredited StandardsCommittees, and approved as American National Standards by ANSI, the ASAStandards Secretariat arranges for their publication and distribution.An American National Standard implies a consensus of those substantially con-cerned with its scope and provisions. Co
10、nsensus is established when, in thejudgment of the ANSI Board of Standards Review, substantial agreement hasbeen reached by directly and materially affected interests. Substantial agreementmeans much more than a simple majority, but not necessarily unanimity. Consen-sus requires that all views and o
11、bjections be considered and that a concertedeffort be made towards their resolution.The use of American National Standards is completely voluntary. Their existencedoes not in any respect preclude anyone, whether he or she has approved thestandards or not, from manufacturing, marketing, purchasing, o
12、r using products,processes, or procedures not conforming to the standards.NOTICE: This American National Standard may be revised or withdrawn at anytime. The procedures of the American National Standards Institute require thataction be taken periodically to reaffirm, revise, or withdraw this Standar
13、d.Standards SecretariatAcoustical Society of America120 Wall Street, 32nd FloorNew York, New York 10005-3993USATelephone: 11 212 248 0373Telefax: 11 212 248 0146E-mail: asastdsaip.orgInternet: http:/asa.aip.org 1998 by the Acoustical Society of America. This Standard may not be reproduced inwhole or
14、 in part in any form for sale, promotion, or any commercial purpose, or any purposenot falling within the provisions of the Copyright Act of 1976, without prior written permissionof the publisher. For permission, address a request to the Standards Secretariat of theAcoustical Society of America.Cont
15、entsPageForeword ii0 Introduction . 11 Scope, purpose, and applications 11.1 Scope 11.2 Purpose 11.3 Applications . 12 Informative references 13 Definitions 13.1 Polyurethane 13.2 Glycol 13.3 Diisocyanate 13.4 Pre-polymer . 13.5 Chain extender 14 Components 14.1 Glycol 14.2 Diisocyanate 24.3 Chain e
16、xtender 25 Required equipment . 25.1 Vacuum mixer . 25.2 Mold . 25.3 Oven . 26 Preparation of pre-polymer 27 Preparation of chain extender blend . 28 Preparation of final polymer . 2Figure1 Typical dynamic mechanical properties of the standard materialat25C 3iForewordThis Foreword is for information
17、 only, and is not a part of ANSI S2.21-1998 AmericanNational Standard Method for Preparation of a Standard Material for Dynamic MechanicalMeasurements.This Standard was developed under the jurisdiction of Accredited Standards Com-mittee S2, Mechanical Vibration and Shock, which has the following sco
18、pe:Standards, specifications, methods of measurement and test terminology in thefields of mechanical vibration and shock and condition monitoring and diagnos-tics of machines, but excluding those aspects which pertain to biological safety,tolerance, and comfort.At the time this Standard was submitte
19、d to Accredited Standards Committee S2,Mechanical Vibration and Shock, for approval, the membership was as follows:D. J. Evans, ChairR. F. Taddeo, Vice ChairA. Brenig, SecretaryAcoustical Society of America D.J.EvansR. F. Taddeo (Alt.)Boyce Engineering International M.P.BoyceC. Meher-Homji (Alt.)Bru
20、el Tele-phone: 11 212 248 0373; Fax 11 212 248 0146.iiiAmerican National StandardMethod for Preparation ofa Standard Material forDynamic MechanicalMeasurements0 Introduction0.1 This Standard concerns the preparation of astandard material for use in the calibration of in-struments for measuring the d
21、ynamic mechanicalproperties of viscoelastic materials.0.2 The standard material is chemically classi-fied as a polyurethane.0.3 The component materials required for thepreparation of the standard material are specifiedin clause 4.0.4 The laboratory equipment required for thepreparation of the standa
22、rd material is specified inclause 5.0.5 In the context of this Standard, the phrasedynamic mechanical properties means the loga-rithmic frequency dependence of modulus andloss factor at a given reference temperature.1 Scope, purpose, and applications1.1 ScopeThis Standard applies to the preparation
23、of a stan-dard material for calibration of instruments formeasuring the dynamic mechanical properties ofviscoelastic materials.1.2 PurposeThe purpose of this Standard is to assist users ofdynamic mechanical test equipment in preparingthe standard material from its basic components.1.3 ApplicationsTh
24、e standard material is used for the calibration ofnew instruments in comparison with other instru-ments and in checking the operation of the sameinstrument at different times.2 Informative references1 ASTM Method D2572-91. Standard TestMethod for Isocyanate Groups in Urethane Mate-rials or Prepolyme
25、rs.2 W. M. Madigosky and G. F. Lee, Improvedresonance technique for material characteriza-tion, J. Acoust. Soc. Am. 73, 1374-1377 (1983).3 J. D. Ferry, Viscoelastic Properties of Poly-mers, 3rd ed., Wiley, New York, 1980, pp 264-320.3 DefinitionsFor the purposes of this Standard, the followingdefini
26、tions apply:3.1 polyurethane. A polymer containing thegroup -NHCOO-.3.2 glycol. A compound terminated with -OHgroups.3.3 diisocyanate. A compound terminated with-NCO groups.3.4 pre-polymer. Low molecular weight mate-rial formed by the reaction of a glycol with a largeexcess of diisocyanate.3.5 chain
27、 extender. Compound terminated with-OH groups added to a pre-polymer to completethe reaction of the isocyanate groups and form thefinal polymer.4 ComponentsThe material shall be a three component system: aglycol, a diisocyanate, and a chain extender blendof two chemicals.4.1 GlycolThe glycol shall b
28、e polytetramethylene ether glycolof nominal molcular weight 2000. Abbreviation:PTMG2000. The chemical formula for this compo-nent isHO-CH2!4O#n-Hwhere the value of n determines the molecularweight. CAS Registry numbers 25190-0601 and24979-97-3.AMERICAN NATIONAL STANDARD ANSI S2.21-19981 1998 Acousti
29、cal Society of America4.2 DiisocyanateThe diisocyanate shall be 4,4-diphenylmethane-diisocyanate. Abbreviation: MDI. The chemical for-mula for this component isOCN-C6H4-CH2-C6H4-NCOCAS Registry number 101-68-8.4.3 Chain extenderThe chain extender shall be a blend of two com-pounds:(1) 2,2-dimethyl-1
30、,3-propanediol. Abbreviation:DMPD. The chemical formula for this com-pound isHOCH2-CCH3!2-CH2OHCAS Registry number 126-30-7;(2) 1,4-butanediol. Abbreviation: BDO. Thechemical formula for this component isHO-CH2!4OHCAS Registry number 110-63-4.5 Required equipment5.1 Vacuum mixerA vacuum mixer, with
31、the following specifications,shall be used for the reaction of the components:(1) mixer size: between 200 g and 1 kg;(2) vacuum: at least 99.9 kPa;(3) temperature range: room temperature to100 C.5.2 MoldMolds shall be made of aluminum of at least 0.5 in.wall thickness. The material shall be poured f
32、romthe bottom of the mold. The mold shall be made sothat only the smallest dimension of the molded partis open to the atmosphere. A silicone mold releaseshould be applied before the material is poured.5.3 OvenAn oven with the following specifications shall beused for curing the specimen in the mold:
33、(1) size: sufficient to accommodate the mold;(2) temperature range: room temperature to150 C;(3) temperature control: within 62C.6 Preparation of pre-polymerBatch size shall be no more than 1 kg.6.1 Heat PTMG to 60 C and de-gas for 30 min-utes after the material is fully melted.6.2 Heat MDI to 50 C
34、until all the MDI is thor-oughly melted.6.3 Add four moles of MDI slowly to one mole ofPTMG while maintaining 50 C to 55 C. This mix-ture produces an exotherm that raises the tem-perature. After the MDI has been added, hold themixture at 75 C to 80 C for one to two hoursunder nitrogen while stirring
35、 with a laboratory me-chanical mixer at slow speed. Then de-gas, cool,and seal under nitrogen.6.4 Determine the percent free isocyanate(NCO) in the pre-polymer. If the measured percentfree NCO is no more than 5 % higher or lower thanthe theoretical NCO, the pre-polymer is ready tobe used. Use the me
36、asured NCO rather than thetheoretical. If the measured NCO is more than 5 %higher than theoretical, the materials shall be re-jected. If the measured NCO is more than 5 %lower than theoretical, heat the mixture at 75 C to80 C until the NCO is within5%oftheoretical.Store the pre-polymer at room tempe
37、rature undera dry nitrogen blanket. The shelf life is no morethan two weeks.NOTE - ASTM Method D2572 1 has been found tobe an acceptable method for determining the percentfree isocyanate.7 Preparation of chain extender blendThe appropriate amount of chain extender blend is5 % less than the stoichiom
38、etric three moles.7.1 At room temperature, add 15 % by weightliquid BDO to 85 % by weight solid DMPD.7.2 Heat the mixture to 110 C and maintain thattemperature until all the DMPD is melted.7.3 Once all the DMPD is melted, stir gently witha spatula to ensure proper mixing. Maintain theblend at 110 C
39、until it is ready to be added to thepre-polymer.8 Preparation of final polymer8.1 Heat the pre-polymer to 80 C to 85 C. Stirand de-gas for about one hour at 80 C to 85 C toANSI S2.21-19982 1998 Acoustical Society of Americaensure a uniform mixture. It is important that thetemperature of the pre-poly
40、mer be at least 80 Cto prevent crystallization of the chain extenderblend when the chain extender blend is added tothe pre-polymer.8.2 Add chain extender blend, at 110 C, to thepre-polymer at 80 C to 85 C. Once all the chainextender blend is added, stir with a laboratoryvacuum mixer at high speed un
41、der vacuum for twominutes.8.3 Pour the mixture into a mold pre-heated to100 C.8.4 Cure for 48 hours at 100 C. Remove fromoven, allow to cool to room temperature, and de-mold.8.5 Post-cure the sample at room temperaturefor one week before testing.NOTE - The cured polymer has the following typicalprop
42、erties:Shore A hardness 5 68;density 5 1.074 g/cm3;Tg5240C.8.6 When evaluated using a resonance tech-nique and time-temperature superposition of thedata 2,3, the standard material should have thedynamic mechanical properties shown in figure 1.Figure 1 Typical dynamic mechanical prop-erties of the st
43、andard material at 25 C.ANSI S2.21-19983 1998 Acoustical Society of AmericaOTHER ACOUSTICAL STANDARDS AVAILABLE FROM THE STANDARDS SECRETARIAT OFTHE ACOUSTICAL SOCIETY OF AMERICA ASA NOISE STDS INDEX 3-1985 Index to Noise StandardsS1 STANDARDS ON ACOUSTICS ANSI S1.1-1994 American National Standard A
44、coustical Ter-minology ANSI S1.4-1983 R 1997 American National Standard Speci-fication for Sound Level Meters ANSI S1.4A-1985 Amendment to S1.4-1983 ANSI S1.6-1984 R 1997 American National Standard Pre-ferred Frequencies, Frequency Levels, and Band Numbers forAcoustical Measurements ANSI S1.8-1989 R
45、 1997 American National Standard Refer-ence Quantities for Acoustical Levels ANSI S1.9-1996 American National Standard Instruments forthe Measurement of Sound Intensity ANSI S1.10-1966 R 1997 American National StandardMethod for the Calibration of Microphones ANSI S1.11-1986 R 1993 American National
46、 Standard Speci-fication for Octave-Band and Fractional-Octave-Band Analogand Digital Filters ANSI S1.12-1967 R 1997 American National Standard Speci-fication for Laboratory Standard Microphones ANSI S1.13-1995 American National Standard Measurement ofSound Pressure Levels in Air ANSI S1.14-1998 Ame
47、rican National Standard Recommenda-tions for Specifying and Testing the Susceptibility of AcousticalInstruments to Radiated Radio-frequency ElectromagneticFields, 25 MHz to 1 GHz ANSI S1.15-1997 Part 1 American National Standard Mea-surement Microphones, Part 1: Specifications for LaboratoryStandard
48、 Microphones ANSI S1.20-1988 R 1993 American National Standard Pro-cedures for Calibration of Underwater Electroacoustic Transduc-ers ANSI S1.22-1992 R 1997 American National Standard Scalesand Sizes for Frequency Characteristics and Polar Diagrams inAcoustics ANSI S1.25-1991 R 1997 American Nationa
49、l Standard Speci-fication for Personal Noise Dosimeters (Revision of ANSI S1.25-1978) ANSI S1.26-1995 American National Standard Method for theCalculation of the Absorption of Sound by the Atmosphere ANSI S1.40-1984 R 1997 American National Standard Speci-fication for Acoustical Calibrators ANSI S1.42-1986 R 1992 American National Standard De-sign Response of Weighting Networks for Acoustical Measure-ments ANSI S1.43-1997 American National Standard Specificationsfor Integrating-Averaging Sound Level MetersS2 STAN
