Boron nitride-reinforced porous aramid composites with enhanced mechanical performance and thermal conductivity

Aramids are materials with high-performance properties and used in advanced applications, including bulletproof vests and aerospace industry components. Consequently, research is focused on improving their properties and reducing their density to achieve fuel reduction and enhanced comfort. Herein we describe the preparation of dense, micro, and nanoporous aramid films containing hexagonal boron nitride (hBN) with two objectives: improving mechanical performance and increasing thermal conductivity (TC) in porous films for specific applications. The preparation procedure is simple and scalable, involving the addition of hBN and a porosity promoter to control the porous structure in the film's casting solution. Tensile tests revealed that the inclusion of 10% of hBN in microporous aramids led to a 130% increase in Young's modulus and 63% reduction in material's density compared to the dense commercial aramid. The orientation of the hBN in the films was also evaluated by considering the XRD and the thermal properties of the films. The films containing hBN exhibited enhanced TC and thermal diffusivity (TD) together with a very low density and improved mechanical performance, which can benefit applications in the aerospace industry, protective equipment, and battery separators.