Ajay Krishnamurthy, Ran Tao, Erkan Senses, Sagar Doshi, Erik Thostenson, Faraz Burni, Bharath Natarajan, Donald L. Hunston, Amanda L. Forster, Aaron M. Forster
Carbon-nanotube (CNT) grafted glass fiber reinforced epoxy nanocomposites (GFRP) present a hierarchy of stiffness (GPa to MPa) and lengths (µm to nm) scales at the fiber-matrix interphase. The contribution of interfacial CNT networks to the local and bulk polymer dynamics is not well understood and is studied here using a combination of dynamical mechanical thermal analysis (DMTA) and neutron scattering experiments (NSE). DMTA outcomes from CNT-GFRP highlight a softening of the storage modulus (G') and a broadening of the loss modulus (G'') throughout the α-transition, accompanied by a minor reduction in α-transition temperature (Tα 5 °C). NSE measurements indicate that the amine-functionalized CNT interphase results in a higher hydrogen mean square displacement (MSD) across a wider temperature range than the GFRP. The amine- functionalized CNT interphase (thickness 100 nm to 5 µm) localized at the fiber surface imparts a rich viscoelastic behavior that is uniquely different from GFRP composites or dispersed CNT nanocomposites.