Simultaneous improvement of electromagnetic interference shielding and mechanical properties of a multilayer-structured CNT/regenerated cellulose composite.
Lightweight
conductive polymer composites based on biomass could
be a promising candidate for electromagnetic interference (EMI) shielding
application. Herein, tailoring porous microstructure and regulating
the distribution of carbon nanotubes (CNTs) in cellulose composites
are attempts to achieve highly efficient EMI shielding properties
accompanying desired mechanical property and low density. Specifically,
aligned porous structure is fabricated by ice-template freeze-drying
method; meanwhile, CNT is regulated to decorate inside the cellulose
matrix (CNT-matrix/cellulose porous composites) or to directly bind
over the cellulose cell walls (CNT-interface/cellulose porous composites).
It is found that, owing to the preferential distribution of CNT on
the cell walls, the CNT-interface/cellulose porous composites possess
a very high electrical conductivity of 38.9 S m–1 with an extremely low percolation threshold of 0.0083 vol % with
regard to CNT-matrix/cellulose porous composites. Therefore, a shielding
effectiveness of 40 dB with merely 0.51 vol % CNT under a thickness
of 2.5 mm is achieved in CNT-interface/cellulose porous composites,
which is attributed to efficient multiple reflections and the accompanying
absorption with promoted conductivity and better-defined porous structure.
More laudably, the CNT-interface/cellulose porous composites reveal
a superior mechanical property with a specific modulus of 279 MPa
g–1 cm3. The value behind the current
work is to pave an effective way to fabricate environmentally benign,
high-performance EMI shielding materials to practically boost numerous
advanced applications of cellulose.
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