Significance and Use
5.1 It is well known that the prepreg impregnation level affects handling characteristics, tack and drape, and final part quality. Resin impregnation level is the dominant factor in the ability of removing air and volatiles from the layup during processing. Partially impregnated prepreg materials can in some applications provide higher quality, lower void content composite parts, and are becoming increasingly more common due to the desire to cure out-of-autoclave, using vacuum bag-only processes. This test can identify small changes in the material impregnation level which can assist in definition of production processes or shipping and handling procedures. The value of permeability can be used for specifying ranges as acceptance requirements for prepreg materials, thus enabling the prepreg manufacturer and user greater confidence in the ability to produce repeatable and high quality parts. This test directly determines the actual air flow propensity of the material tested without any applied compaction pressure during testing.
5.2 Factors that influence the permeability of the tested prepreg material shall be reported including: prepreg material, orientation, location on roll, width, length, thickness, and actual atmospheric pressure.
1.1 This test method determines the in-plane permeability of composite prepreg (pre-impregnated) materials as a measure of level of impregnation. Permissible prepreg materials include those reinforced with carbon, glass, aramid, thermoplastic and other fibers impregnated with a thermoset or thermoplastic matrix resin, creating a single ply sheet material. The reinforcements may be unidirectional or woven fabrics.
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, the 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.