# Small-Scale Processing of High-Performance BNNT Fiber for Space and Electronics Applications

## TL;DR

This paper presents a new method to create high-performance BNNT fibers with excellent mechanical properties and alignment, suitable for aerospace and electronics.

## Contribution

The novel contribution is achieving the highest alignment and mechanical performance in BNNT fibers to date.

## Key findings

- BNNT fibers achieved a modulus of up to 396 GPa and tensile strength of up to 500 MPa.
- The alignment of BNNTs in the fiber is the highest ever achieved in nanotube-based fibers.
- The fibers show significant porosity and can be knotted, indicating suitability for textile processing.

## Abstract

A method to process boron nitride nanotube (BNNT) fibers
with a
high degree of alignment, high modulus, and good tensile strength
is presented. This has been achieved by dispersing BNNTs in a polymer
solution, spinning the resulting polymer/BNNT dispersion into fibers,
and removing the polymer. Significant alignment is imparted to the
BNNTs within the fiber during drawing and heat treatment under tension.
These BNNT fibers are characterized structurally and elementally to
confirm the BNNT structure. This work has resulted in a highly oriented
BNNT fiber with a modulus as high as 396 GPa and a tensile strength
as high as 500 MPa. These tensile values represent the current state
of the art for BNNT fibers, and the alignment of BNNTs in the fiber
is the highest ever achieved for nanotubes-based fibers. Significant
porosity is observed from the TEM images of the BNNT fibers’
cross section, indicating that further processing optimization can
be expected to further increase these properties. A knot can be made
in some of the resulting BNNT fibers, suggesting that some of these
BNNT fibers are suitable for typical textile processing techniques.
BNNT fibers, their textile preforms, and BNNT fiber containing composites
will be suitable for applications requiring high thermal conductivity
without electrical conductivity, high temperature oxidative resistance,
and low dielectric constant, particularly in aerospace and electronics
areas.