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Cellulose Nanocrystal-Enabled Tailoring of the Interface in Carbon Nanotube- and Graphene Nanoplatelet-Carbon Fiber Polymer Composites: Implications for Structural Applications

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journal contribution
posted on 14.01.2022, 22:13 by Ozge Kaynan, Lisa M. Pérez, Amir Asadi
Cellulose nanocrystals (CNCs) enable the effective coating of carbon fibers (CFs) with pristine carbon nanotubes (CNTs) and graphene nanoplatelets (GnPs). Herein, we articulate the mechanisms that form the interface of CNC-bonded CNT and CNC-bonded GnP-CF reinforced polymer (CFRP) composites that are suitable for structural applications. We show that CNCs provide a suitable platform to engineer the interface of hybrid composites. We demonstrate that the hybrid nanomaterials, i.e., CNC and CNT/GnP, alter the chemical composition of the interface and its properties, and despite the similar elemental composition of the CNT and GnP, the mechanical properties of the produced composites differ. Our results show that the presence of CNC–CNT and CNC–GnP creates a 4 μm interfacial region that leads to a 200 and 145% increase in interfacial shear strength and a 46 and 28% enhancement in interlaminar shear strength, respectively. Furthermore, density functional theory calculations show that the binding energy between the CNC–CNT and CF sizing agent is 14% higher than that of CNC–GnP underlining the effect of chemical and physical interactions in the observed difference in mechanical properties. The understanding gained from this study highlights a path forward bottom-up manufacturing of hybrid composites with an engineered microstructure and properties from the molecular level and nanoscale to higher scales.