1、Designation: D 3532 99 (Reapproved 2004)Standard Test Method forGel Time of Carbon Fiber-Epoxy Prepreg1This standard is issued under the fixed designation D 3532; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 method covers the determination of
3、 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 SI units are to be regarded asstandard. The values in parentheses are for reference only.1.3 This standard does not p
4、urport 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Summary of Test Method2.1 A specimen of
5、prepreg material approximately 5 mm(0.25 in.) square is placed between microscope cover glasseson a hot plate preheated to either of two test temperatures, 120or 175C (250 or 350F). Pressure is applied to the specimenthrough the coverglass with a wood pick to form a bead of resinat the edge of the c
6、over glass. The time from the application ofheat until the resin ceases to form strings by contact with thepick is noted and reported as the gel time.3. Significance and Use3.1 This test method can be used to obtain the gel time ofresin squeezed from prepreg tape or sheet material. This test isa use
7、ful measure for material acceptance.3.2 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 9.1.2.3.
8、3 Gel time is not recommended as a measure of outline(unacceptable degree of cross-linking). Use Resin Flow TestMethod D 3532, or Dynamic Viscosity Practice D 4473.4. Apparatus4.1 Cutting Knife.4.2 Hot Plate, capable of maintaining temperatures of either120C (250F) or 175C (350F) and the means of me
9、asuringits surface temperature to an accuracy of 61C (62F).4.3 Stopwatch or Suitable Timer, capable of reading 1-sintervals up to 60 min.4.4 Microscope Coverglasses, 18 to 22 mm (0.7 to 0.9 in.)in diameter.4.5 Wooden Probe, small, such as a toothpick, mounted in adrafting pencil holder or fine glass
10、 rod. A low thermal capacityis needed.5. Interferences5.1 The test is a subjective measure of when a gel point isreached. The visual evidence of gel may vary between mate-rials, reinforcements, and, in some cases, between resin mate-rial batches. If the definition of gel in this method is notsuffici
11、ently standard for a given material, interested partiesshall agree on a further definition of gelation.6. Test Specimen6.1 A minimum of three specimens shall be tested for eachsample.6.2 The test specimen shall consist of prepreg material cutto approximately 6-mm (0.25-in.) square.7. Conditioning7.1
12、 Store carbon fiber-epoxy prepreg tape at low tempera-tures, approximately 18C (0F), to prolong the usefulness ofthe material. Allow the sealed packages of material to warm toambient temperature before the seal is opened to ensure that thematerial does not absorb moisture from the atmosphere.8. Proc
13、edure8.1 Cut the specimen of prepreg.8.2 Preheat the hot plate to either test temperature A, 120 61C (250 6 2F) or B, 175 6 1C (350 6 2F) or thetemperature that has been specified.8.3 Place a cover glass on the hot plate and allow 20 s for itto reach temperature.1This test method is under the jurisd
14、iction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.03 onConstituent/Precursor Properties.Current edition approved Oct. 1, 2004. Published October 2004. Originallyapproved in 1976. Last previous edition approved in 1999 as D 3532 99.1Copyright ASTM
15、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8.4 Place the specimen in the center of the coverglass andcover it with another coverglass.8.5 Commence timing immediately.8.6 Probe the surface of the coverglass to apply pressure tothe prepreg speci
16、men. Use the probe to isolate a bead of resinat the edge of the specimen. Continue to probe the bead of resinand observe its tendency to form strings. Select the point atwhich strings cannot be formed by contact with a pick as thegel time. Record this time as gel time.9. Report9.1 The report shall i
17、nclude the following.9.1.1 Complete identification of the material including thefiber type, the fiber manufacturer, surface treatment of the fiber,the resin type, the resin manufacturer, and prepreg supplier,9.1.2 The test temperature, and9.1.3 The gel time reported to the nearest 1 s.10. Precision
18、and Bias10.1 The precision, defined as the degree of mutual agree-ment between individual measurements, can be estimated fromthe results of a round robin conducted on two samples ofprepreg by four laboratories, each laboratory making threemeasurements of each sample. The coefficient of variation for
19、measurements on one material, mean gel time of 6.8 min was41.7 % and 51.6 % on the other material which had a mean geltime of 5.6 min. No modern precision statement is available.10.2 No estimate of bias can be offered as no acceptedreference level is available.11. Keywords11.1 carbon fiber-epoxy pre
20、preg; 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 expressly advised that determination of the validity of any such patent rights, and the riskof infringement of su
21、ch 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, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for addi
22、tional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to th
23、e 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. 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).D 3532 99 (2004)2
