Functionalized glass fibers cloth/spherical BN fillers/epoxy laminated composites with excellent thermal conductivities and electrical insulation properties

Thermally conductive glass fibers cloth/spherical boron nitride fillers/epoxy (GFs/BN/epoxy) laminated composites with excellent electrical insulation properties were fabricated by blending-impregnation followed by hot compression method. Epichlorohydrin (ECH) was successfully grafted onto the surface of GFs (f-GFs), in favor of improving the mechanical properties of the f-GFs/epoxy laminated composites. For a given spherical BN fillers loading, GBN-100 with relatively larger particle size was more benefit for enhancing the thermal conductivities of the BN/epoxy composites. Meantime, thermal conductivity coefficient (λ) values of the f-GFs/GBN-100/epoxy laminated composites were gradually enhanced with the increasing addition of GBN-100 fillers. When the mass fraction of GBN-100 fillers was 20 wt%, the λ in vertical (λ_⊥) and parallel (λ_∥) of the f-GFs/GBN-100/epoxy laminated composites was the maximum of 1.21 and 3.55 W m⁻¹K⁻¹, about 3 and 6 times than that of the f-GFs/epoxy laminated composites (λ_⊥ of 0.41 W m⁻¹K⁻¹ and λ_∥ of 0.66 W m⁻¹K⁻¹), respectively, and much higher than that of pure epoxy matrix (0.23 W m⁻¹K⁻¹). Meantime, the surface resistivity and breakdown strength of the f-GFs/GBN-100/epoxy laminated composites with 20 wt% GBN-100 fillers was respectively decreased to 5.1*10¹⁴ Ω and 7 KV mm⁻¹, but still maintained excellent electrical insulation properties.