ASTM_D_3532_-_D_3532M_-_19.pdf

Designation:D3532/D3532M19Standard Test Method forGel Time of Carbon Fiber-Epoxy Prepreg1This standard is issued under the fixed designation D3532/D3532M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of gel time ofcarbon fiber-epoxy tape and sheet.The test method is suitablefor the measurement of gel time of resin systems having eitherhigh or low viscosity.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system are not necessarily exact equivalents;therefore,toensure conformance with the standard,each system shall beused independently of the other,and values from the twosystems shall not be combined.1.2.1 Within the text,inch-pound units are shown in brack-ets.1.3 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D3531/D3531M Test Method for Resin Flow of CarbonFiber-Epoxy PrepregD4473 Test Method for Plastics:Dynamic Mechanical Prop-erties:Cure BehaviorD7750 Test Method for Cure Behavior of ThermosettingResins by Dynamic Mechanical Procedures using anEncapsulated Specimen Rheometer3.Summary of Test Method3.1 A specimen of prepreg material approximately 5 mm0.25 in.square is placed between microscope coverglasses ona hot plate preheated to either of two test temperatures,120 or175 C 250 or 350 F.Pressure is applied to the specimenthrough the coverglass with a wood pick to manipulate theresin.The time from the application of heat until the resinceases to flow by contact with the pick is noted and reported asthe gel time.4.Significance and Use4.1 This test method can be used to obtain the gel time ofresin squeezed from prepreg tape or sheet material.This test isa useful measure for material acceptance.4.2 The gel time will vary with the test temperature.Thetemperatures specified in this test method are two of manytemperatures often used in processing epoxy prepreg material.If other test temperatures are used,this is to be clearly noted asindicated in 10.1.2.4.3 Gel time is not recommended as a measure of out time(unacceptable degree of cross-linking).Use Resin Flow TestMethod D3531/D3531M,Dynamic Viscosity Test MethodD4473,or Dynamic Mechanical Procedures Test MethodD7750.5.Interferences5.1 The test is a subjective measure of when a gel point isreached.The visual evidence of gel may vary betweenmaterials,reinforcements,and,in some cases,between resinmaterial batches.If the definition of gel in this method is notsufficiently standard for a given material,interested partiesshall agree on a further definition of gelation.6.Apparatus6.1 Cutting Knife.6.2 Hot Plate,of either of the following types:6.2.1 Class A Hot Plate,capable of maintaining tempera-tures of either 120 C 250 F or 175 C 350 F and themeans of measuring its surface temperature to an accuracy of61 C 62 F.1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.03 onConstituent/Precursor Properties.Current edition approved Sept.1,2019.Published September 2019.Originallyapproved in 1976.Last previous edition approved in 2012 as D3532/D3532M 12.DOI:10.1520/D3532_D3532M-19.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 6.2.2 Class B Hot Plate,capable of maintaining tempera-tures of either 120 C 250 F or 175 C 350 F and themeans of measuring its surface temperature to an accuracy of63 C 65 F.6.2.3 If no class of hot plate is s