1 research outputs found
Achieving a Collapsible, Strong, and Highly Thermally Conductive Film Based on Oriented Functionalized Boron Nitride Nanosheets and Cellulose Nanofiber
Boron
nitride nanosheet (BNNS) films receive wide attention in both academia
and industry because of their high thermal conductivity (TC) and good
electrical insulation capability. However, the brittleness and low
strength of the BNNS film largely limit its application. Herein, functionalized
BNNSs (f-BNNSs) with a well-maintained in-plane crystalline structure
were first prepared utilizing urea in the aqueous solution via ball-milling
for the purpose of improving their stability in water and enhancing
the interaction with the polymer matrix. Then, a biodegradable and
highly thermally conductive film with an orderly oriented structure
based on cellulose nanofibers (CNFs) and f-BNNSs was prepared just
by simple vacuum-assisted filtration. The modification of the BNNS
and the introduction of the CNF result in a better orientation of
the f-BNNS, sufficient connection between f-BNNS themselves, and strong
interaction between f-BNNS and CNF, which not only make the prepared
composite film strong and tough but also possess higher in-plane TC.
An increase of 70% in-plane TC, 63.2% tensile strength, and 77.8%
elongation could be achieved for CNF/f-BNNS films, compared with that
for CNF/BNNS films at the filler content of 70%. Although at such
a high f-BNNS content, this composite film can be bended and folded.
It is even more interesting to find that the in-plane TC could be
greatly enhanced with the decrease of the thickness of the film, and
a value of 30.25 W/m K can be achieved at the thickness of ∼30
μm for the film containing 70 wt % f-BNNS. We believe that this
highly thermally conductive film with good strength and toughness
could have potential applications in next-generation highly powerful
and collapsible electronic devices