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An Acrylonitrile–Butadiene–Lignin Renewable Skin with Programmable and Switchable Electrical Conductivity for Stress/Strain-Sensing Applications
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posted on 2017-12-28, 12:24 authored by Ngoc A. Nguyen, Kelly M. Meek, Christopher C. Bowland, Sietske H. Barnes, Amit K. NaskarWe report an approach for programming
electrical conductivity of a bio-based leathery skin devised with
a layer of 60 nm metallic nanoparticles. Lignin-based renewable shape-memory
materials were made, for the first time, to program and restore the
materials’ electrical conductivity after repeated deformation
up to 100% strain amplitude, at a temperature 60–115 °C
above the glass transition temperature (Tg) of the rubbery matrix. We cross-linked lignin macromolecules with
an acrylonitrile–butadiene rubbery melt in high quantities
ranging from 40 to 60 wt % and processed the resulting thermoplastics
into thin films. Chemical and physical networks within the polymeric
materials significantly enhanced key characteristics such as mechanical
stiffness, strain fixity, and temperature-stimulated recovery of shape.
The branched structures of the guaiacylpropane-dominant softwood lignin
significantly improve the rubber’s Tg and produced a film with stored and recoverable elastic work density
that was an order of magnitude greater than those of the neat rubber
and of samples made with syringylpropane-rich hardwood lignin. The
devices could exhibit switching of conductivity before and after shape
recovery.