Standard Test Method for Characterizing Tack of Prepregs Using a Continuous Application-and-Peel Procedure

Abstract

5.1 Characterizing tack for different prepreg materials, test parameters, surface combinations, and environmental conditions provides insight for optimizing process parameters (particularly deposition rate and deposition temperature) for industrial automated material placement processes. 5.2 Results obtained through employing the continuous application-and-peel method, as described in studies (1-3),3 reflect the effects of adhesion forming between prepreg layers or between prepreg and metal substrate, and loss of cohesion within the resin in the prepreg, upon tack. This test method allows the adhesive properties of B-staged resin to be explored in a manner relevant for dynamic material deposition processes, where timescales for bonding of prepreg to the substrate or previously placed prepreg layers are short prior to curing. In contrast, Test Methods D3167 and D1781 determine the peel resistance of adhesive bonds for adhesion measurement and process control of laminated or bonded adherends. 5.3 The test method is suitable to quantify tack of prepregs for acceptance and process control and can be extended to determine resin shelf life or to adjust process parameters to resin out-time. Direct comparison of different resins/prepregs or processes can only be made when specimen preparation and test conditions are identical.