Conductive
nanofillers usually act as nucleating agents in the
semicrystalline polymer matrix, and the crystals formed on the filler
surface can impede electrical percolation development. In this work,
flexible poly(ether-block-amide)/carbon nanotube (PEBA/CNT) nanocomposites
were fabricated for electromagnetic interference (EMI) shielding applications.
It was demonstrated that CNTs can nucleate the crystallization of
the polyamide (PA) block of PEBA and induce the transformation of
the crystals from the γ-form to the α-form. Reducing the
content of the PA block in PEBA from 50 to 20 wt % decreased the crystallinity
of the nanocomposite and thus resulted in a higher electrical conductivity
and an increment in EMI shielding performances. However, when ionically
conductive polyethylene oxide was used as the polyether block, the
hindrance effect of PA crystallization on electrical percolation was
effectively mitigated, allowing for both high conductivity and enhanced
amide dipole moment with a high PA content (e.g., 50 wt %), which
is favorable for electromagnetic wave absorption. As a result, a high
EMI shielding effectiveness with increased absorption can be achieved
in PEBA/CNT nanocomposites.