Halloysite nanotube enhanced polyurethane nanocomposites for advanced electroinsulating applications

Halloysite nanotubes (HNT), as naturally occurring anisotropic nanofillers, were incorporated into a commercial two-component (2C) polyurethane (PU) system to develop multifunctional nanocomposites for electroinsulating applications. The nanocomposites were prepared via the method of direct dispersion. Dielectric, thermal, and mechanical properties were systematically analyzed at weight concentrations of 2 wt%, 5 wt%, and 10 wt% of HNT in the PU matrix. At 5 wt% HNT, an optimal balance was observed: volume resistivity increased nearly 17-fold, dielectric permittivity was enhanced through Maxwell–Wagner–Sillars interfacial polarization, and thermal conductivity rose modestly while maintaining high mechanical integrity. Broadband dielectric spectroscopy, modeled using the Havriliak–Negami function, showed broadened relaxation dynamics associated with filler–matrix interfaces. Incorporation of 10 wt% HNT caused agglomeration, reducing property uniformity. The results demonstrate that controlled integration of HNT into cold-curing 2C PU systems yields cost-effective, sustainable, and high-performance nanodielectrics, advancing their potential use in high-voltage insulation, aerospace encapsulation, and battery module safety.