Electromechanical sensors based on carbon nanotube networks and their polymer composites

Abstract

A network of entangled multiwall carbon nanotubes and the composite consisting of filter-supported multiwall carbon nanotube network are conductors whose conductivity is sensitive to compressive stress both in the course of monotonic stress growth and when loading/unloading cycles are imposed. The testing has shown as much as 100% network conductivity increase at the maximum applied stress. The entangled carbon nanotube net-works are prepared by vacuum filtration method and peeled off from the filter. The carbon nanotubes are used in pristine condition or chemically functionalized. The filter-supported entangled networks are prepared by the nanotube dispersion filtration through a non-woven flexible polystyrene filter. The nanotubes infiltrate partly into the filter surface pores and link the accumulated filtrate layer with the filtering mat. The filter-support increases nano-tube network mechanical integrity, the composite tensile ultimate strength and affects fa-vorably the composite electrical resistance. Other obvious effect of the supporting polymer is reduction of the resistance temperature dependence. Moreover, the conductivity of car-bon nanotube networks manifests also organic vapor dependence. The dependence is re-versible, reproducible, selective as well as possibly influenced by nanotube oxidation.(http://www.springerlink.com/content/w7n2167k2m4k8002)