1、Designation:D353299 (Reapproved 2009) Designation: D3532/D3532M 12Standard 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 o
2、f 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 Department of Defense.1. Scope1.1 This test met
3、hod covers the determination of gel time of carbon fiber-epoxy tape and sheet. The test method is suitable forthe measurement of gel time of resin systems having either high or low viscosity.1.2The values stated in SI units are to be regarded as standard. The values in parentheses are for reference
4、only.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conforman
5、ce with the standard.1.2.1 Within the text, inch-pound units are shown in brackets.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and
6、determine the applicability of regulatorylimitations prior to use.2. Summary of Test Method2.1 Aspecimen of prepreg material approximately 5 mm (0.25 in.)0.25 in. square is placed between microscope cover glasseson a hot plate preheated to either of two test temperatures, 120 or 175C (250250 or 350F
7、).350F. Pressure is applied to thespecimen through the coverglass with a wood pick to form a bead of resin at the edge of the cover glass. The time from theapplication of heat until the resin ceases to form strings by contact with the pick is noted and reported as the gel time.3. Significance and Us
8、e3.1 This test method can be used to obtain the gel time of resin squeezed from prepreg tape or sheet material. This test is a usefulmeasure for material acceptance.3.2 The gel time will vary with the test temperature. The temperatures specified in this test method are two of many temperaturesoften
9、used in processing epoxy prepreg material. If other test temperatures are used, this is to be clearly noted as indicated in 9.1.2.3.3 Gel time is not recommended as a measure of outline (unacceptable degree of cross-linking). Use Resin Flow Test MethodD3532, or Dynamic Viscosity Practice D4473.4. Ap
10、paratus4.1 Cutting Knife.4.2 Hot Plate, capable of maintaining temperatures of either 120C (250F)250F or 175C (350F)350F and the means ofmeasuring its surface temperature to an accuracy of 61C (62F). 62F.4.3 Stopwatch or Suitable Timer, capable of reading 1-s intervals up to 60 min.4.4 Microscope Co
11、verglasses, 18 to 22 mm (0.70.7 to 0.9 in.)in. in diameter.4.5 Wooden Probe, small, such as a toothpick, mounted in a drafting pencil holder or fine glass rod. A low thermal capacity isneeded.5. Interferences5.1 The test is a subjective measure of when a gel point is reached. The visual evidence of
12、gel may vary between materials,reinforcements, and, in some cases, between resin material batches. If the definition of gel in this method is not sufficiently standardfor a given material, interested parties shall agree on a further definition of gelation.1This test method is under the jurisdiction
13、of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.03 onConstituent/Precursor Properties.Current edition approved Sept.May 1, 2009.2012. Published November 2009.June 2012. Originally approved in 1976. Last previous edition approved in 20042009 asD3532 9
14、9(20049). DOI: 10.1520/D3532-99R09. 10.1520/D3532_D3532M-12.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all cha
15、nges accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, U
16、nited States.6. Test Specimen6.1 A minimum of three specimens shall be tested for each sample.6.2 The test specimen shall consist of prepreg material cut to approximately 6-mm (0.25-in.)0.25-in. square.7. Conditioning7.1 Store carbon fiber-epoxy prepreg tape at low temperatures, approximately 18C (0
17、F),0F, to prolong the usefulness ofthe material. Allow the sealed packages of material to warm to ambient temperature before the seal is opened to ensure that thematerial does not absorb moisture from the atmosphere.8. Procedure8.1 Cut the specimen of prepreg.8.2 Preheat the hot plate to either test
18、 temperature A, 120 6 1C (250250 6 2F)2F or B, 175 6 1C (350350 6 2F)2For the temperature that has been specified.8.3 Place a cover glass on the hot plate and allow 20 s for it to reach temperature.8.4 Place the specimen in the center of the coverglass and cover it with another coverglass.8.5 Commen
19、ce timing immediately.8.6 Probe the surface of the coverglass to apply pressure to the prepreg specimen. Use the probe to isolate a bead of resin atthe edge of the specimen. Continue to probe the bead of resin and observe its tendency to form strings. Select the point at whichstrings cannot be forme
20、d by contact with a pick as the gel time. Record this time as gel time.9. Report9.1 The report shall include the following.9.1.1 Complete identification of the material including the fiber type, the fiber manufacturer, surface treatment of the fiber, theresin type, the resin manufacturer, and prepre
21、g supplier,9.1.2 The test temperature, and9.1.3 The gel time reported to the nearest 1 s.10. Precision and Bias10.1 The precision, defined as the degree of mutual agreement between individual measurements, can be estimated from theresults of a round robin conducted on two samples of prepreg by four
22、laboratories, each laboratory making three measurementsof each sample. The coefficient of variation for measurements on one material, mean gel time of 6.8 min was 41.7 % and 51.6 %on the other material which had a mean gel time of 5.6 min. No modern precision statement is available.10.2 No estimate
23、of bias can be offered as no accepted reference level is available.11. Keywords11.1 carbon fiber-epoxy prepreg; gel timeASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are express
24、ly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised,
25、either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may att
26、end. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States.
27、Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D3532/D3532M 122
