Tack Property of Prepregs: Effective Parameters, Methods of Measurement and Failure Mechanisms

Nowadays, due to the development of automated composite manufacturing processeson prepregs, it is necessary to recognize the main properties and factors affectingprepregs. After the precuring stage, the tack is one of the main characteristics of theprepregs, and this parameter is the viscoelastic properties of the prepreg bulk. The tackis the ability of prepreg to stick to itself or to other surfaces. Factors affecting prematuretack can be divided into two general categories of structural and process factors. Themost important structural factors is the type of resin, resin formulation, molecular weight,viscosity, degree of cure, fabric type, fabric architecture, temperature, volume of cavitiesand volatile content are mentioned. Also, the most important process factors are humiditycontent, aging, contact time, contact force, separation force, lay-up speed and angle. Thecohesive failure and interfacial failure of two mechanisms of failure have been proven intack of prepreg and these two mechanisms are capable of interchanging under differentconditions. Also, due to the lack of a standard test, several different methods, such asfloating roller, probe, rolling ball, peel, lap shear and loop tack test, are used to measurethe amount of tack. In this paper, the factors affecting the prepreg tack, different measuringmethods and different failure modes have been investigated.