Large-scale fabrication of boron nitride nanotubes and their application in thermoplastic polyurethane based composite for improved thermal conductivity

摘要

The large-scale manufacture of inexpensive boron nitride nanotubes (BNNTs) has proven difficult in recent decades. In this study, BNNTs are fabricated on a massive scale by ball-milling a mixture of boron oxide (B2O3), amorphous boron powder (B), and magnesium diboride (MgB2) and then annealing the resulting product in NH3, which follows a vapor-liquid-solid growth mechanism. MgB2 serves as a catalyst in the growth process, and the vaporous B2O3 and diboron dioxide (B2O2) produced from the reaction of B2O3 and B are efficient sources of boron. The obtained BNNTs can be dispersed well in dimethyl formamide, possibly as a result of some cracked structures in the BNNTs and impurities that form during the synthesis process. Taking advantage of the good dispersity, the uniform BNNT/thermoplastic polyurethane composite films are prepared via solution blending. The incorporation of BNNTs apparently enhances the thermal conductivity of the neat thermoplastic polyurethane. This article contributes to the low-cost fabrication of BNNTs and their potential application as fillers in polymers.