Significance and Use 4.1 This test method can be used to obtain the gel time of resin squeezed from prepreg tape or sheet material. This test is a useful measure for material acceptance. 4.2 The gel time will vary with the test temperature. The temperatures specified in this test method are two of many temperatures often used in processing epoxy prepreg material. If other test temperatures are used, this is to be clearly noted as indicated 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 Test Method D3531/D3531M, Dynamic Viscosity Test Method D4473, or Dynamic Mechanical Procedures Test Method D7750.Scope 1.1 This test method covers the determination of gel time of carbon fiber-epoxy tape and sheet. The test method is suitable for the measurement of gel time of resin systems having either high or low viscosity. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 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 responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
