Molecular dynamics modeling to probe the effect of surface functionalization on the interfacial adhesion and shear strength of graphene/epoxy nanocomposites

Document Type

Conference Proceeding

Publication Date

4-15-2021

Department

Department of Mechanical Engineering-Engineering Mechanics

Abstract

Persistent research effort has been devoted for decades in developing materials for the aerospace industry. Among the most crucial requirements in the new generation of aerospace, vehicles are optimizing their structural material stiffness, strength, and fuel-to-weight ratio. Accordingly, it has been established that lightweight polymer-based composite materials represent the ideal alternative to relatively heavy metallic structural alloys. Graphene/epoxy nanocomposites have been attracted much attention due to their exceptional mechanical properties. They have been used in fabricating carbon fiber/graphene/epoxy hybrid composites for improved properties relative to traditional carbon fiber/epoxy composites. This work addresses the interfacial interaction and adhesion in graphene/epoxy nanocomposite materials. This is necessary to investigate and maintain the material integrity at the nanoscale level by tailoring the molecular network structure. Molecular dynamics simulation with a reactive force field was used to quantify the interfacial interaction energy of the nanocomposite constituents, and graphene pull-out simulations were used to determine the interfacial shear strength. It has been shown that surface functionalization of graphene nanoplatelets can significantly increase their interfacial adhesion with the hosting epoxy matrix. The results show that there is a tremendous improvement in the functionalized graphene/epoxy interfacial interaction energy up to ~570%. Furthermore, surface functionalization of graphene nanoplatelets can improve the interfacial shear strength by ~750 times. This substantial improvement is from altering the noncovalent graphene-epoxy interfacial adhesion into strong covalent bonding utilizing the functional groups. Furthermore, the wrinkled and rough topology of functionalized graphene is found to improve the interlocking mechanism with the host matrix. These findings are important to the future of synthesizing next generation ultra-strength and lightweight polymer-based nanocomposite materials.

Publication Title

Earth and Space 2021: Materials, Structures, Dynamics, and Control in Extreme Environments - Selected Papers from the 17th Biennial International Conference on Engineering, Science, Construction, and Operations in Challenging Environments

ISBN

9780784483381

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