Effects of Surface Heterogeneity on Work of Adhesion of Carbon Fiber Reinforced Composites
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2021Author
Kola, Gayathri
Rahman, Minhazur
Vadlamudi, Vamsee
Raihan, Rassel
Reifsnider, Kenneth
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**Please note that the full text is embargoed** ABSTRACT: Carbon Fiber Reinforced Polymers (CFRPs) are increasingly being used in aviation, automotive, renewable energy, and various other industrial sectors, due to their high strength-to-weight ratio, stiffness, and durability. However, due to their brittle nature, joining composites to other structural components can pose a significant risk of crack formation at the fitted regions. Bonding, as opposed to joining, can reduce these potential damages. Hence, it is imperative to improve our understanding of the factors influencing composite bonds. The contact angle directly relates to the readily available energy present on the surface that makes it hydrophilic or hydrophobic, namely, the Surface Free Energy (SFE). Work of adhesion is another characteristic that can be derived from contact angle measurements. It describes the energy required to detach adhesives from the interface of the bonded materials. Assessment of bond strength can be done by measuring these surface characteristics of the adherends. However, CFRPs appear to have heterogeneities due to their roughness, fiber orientation, and surface chemistry. We are interested in examining the contact angle hysteresis that arises from this innate heterogeneity of the adherend surface to predict its suitability for bonding applications. CFRP adherends with different surface roughness and surface chemical profile were tested using the Double Sessile Drop Technique. The variations in SFE and Work of Adhesion measurements were followed by the dynamic contact angle measurements. Due to heterogeneity, large standard deviations were observed in the SFE and Work of Adhesion. Orientational dependence on wettability envelope was observed. [Copyright 2021. Used by CAMX - The Composites and Advanced Materials Expo. CAMX Conference Proceedings. Dallas, TX, October 19-21, 2021. CAMX – The Composites and Advanced Materials Expo.]