Surface energy determination of fibres for Liquid Composite Moulding processes: Method to estimate equilibrium contact angles from static and quasi-static data

Abstract

Interest in eco-composites incorporating elements from recycling is growing to reduce the carbon footprint of final products. Therefore, the characterisation surface properties of recycled fibres is of first importance. However, in order to maximise the service properties and facilitate their development, chemical surface treatments can be made in order to improve fibres compatibility with resins. For a better understanding of the behaviour of these new reinforcements during Liquid Composite Moulding processes (LCM), surface analysis and wetting properties are studied. However, this type of analysis, using the Owens and Wendt relation and based on tensiometric methods, requires special procedures, specifically for estimation of the contact angle. Based on two tensiometric methods, carbon and basalt fibres with different sizing are characterised in first approach, in order to be able to address recycled materials in further studies. The main contribution of this study is to evaluate the error in surface energy and its components determination associated to the measurement of an alleged equilibrium contact angle deriving from static or quasi-static data.