Conductive bio-epoxy/boron nitride nanocomposites: effect of combination of nanotubes and epichlorohydrin surface-modified nanosheets

Bio-epoxy (BE) composites containing boron nitride (BN) and epichlorohydrin (ECH) modified BN nano-scale platelet-like (S), and hybrid EP/ECH-S composites with BN nanotubes (T) were prepared and underwent morphological, thermal, mechanical, thermomechanical, and conductivity analyses. First, BE with S nano-scale filler was mixed in varying filler content by dispersion under high-shear (HS), ultrasonic (U), or HS/U simultaneously. Moreover, S was modified with ECH and added to BE separately to study the effect of surface modification on BE ultimate properties. Combination of ECH-S and T considerably increased thermal conductivity (well above 0.75 W.m(-1).K-1, typical of highly loaded BN systems). Hybrid BE/ECH-S/T systems also showed higher mechanical and thermal stability features. The role of S, ECH-S, and/or T nano-scale fillers on thermal stability is reflected in deceleration and/or less degradation at intermediate and elevated temperatures, depending on formulation. Overall, DSC confirmed formation of stronger 3D filler network within the bio-epoxy after the modification leading to increased thermal stability and conductivity of the hybrid systems. The results showed that the use of ECH modification of BN nanosheets created a dense network with a thermal conductivity at 0.7 W.m(-1).K-1, conventionally according to the reports, increased to 2 W.m(-1).K-1 and mechanical properties at 57 MPa of a reference epoxy increased to 90 MPa for an ECH-modified hybrid system.