Low-loading h-BN/TPU composites processed by thermokinetic shear mixing for injection-molded automotive applications

Official URL: https://dx.doi.org/10.1002/pen.70469

Achieving uniform dispersion and strong interfacial coupling between hexagonal boron nitride (h-BN) and thermoplastic polyurethane (TPU) remains a key challenge for enhancing composite performance. In this study, low-loading h-BN/TPU composites were fabricated using a thermokinetic shear-mixing process, which facilitated efficient platelet breakup and improved filler–matrix interactions. This scalable approach led to simultaneous improvements across thermal conductivity, mechanical stiffness, and crystallization behavior. The in-plane thermal conductivity increased from 0.233 to 0.250 W m−1 K−1 at 3 wt.% h-BN. Notably, the incorporation of h-BN significantly enhanced the mechanical performance, with the tensile flexural moduli increasing by up to 83.6% and by 35%, respectively, indicating efficient load transfer within the matrix. Furthermore, h-BN acted as an effective nucleating agent, substantially elevating the crystallization temperature. The resulting modulus values at 2.0–3.0 wt.% loading align with industry specifications for automotive-grade flexible components, such as sealing elements and protective boots, while maintaining essential elongation capability. A complementary life-cycle analysis (LCA) confirmed the environmental viability of these composites, with global warming potential (GWP) values remaining below 1.0 kg CO2-eq per batch. These findings position low-loading h-BN/TPU composites as sustainable, high-performance candidates for lightweight automotive applications.