Title: Self-sensing of elastic strain, matrix yielding and plasticity in multiwall carbon nanotube/vinyl ester composites

J J Ku-Herrera1, F Avilés,
Centro de Investigación Científica de Yucatán A.C, Unidad de Materiales, Calle 43 No. 130 Colonia Chuburná de Hidalgo, 97200, Mérida, Yucatán, México
Gary Don Seidel,
Dept. of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, 228 Randolph Hall (0203) Blacksburg, VA 24061, USA

Smart Materials and Structures -- 2013 -- 22 085003-1-7

Abstract
The piezoresistive response of multiwalled carbon nanotube/vinyl ester composites containing 0.3, 0.5 and 1% w/w carbon nanotubes (CNTs) loaded in tension and compression is investigated. The change in electrical resistance (?R) under tension loading was positive and showed a linear relationship with the applied strain up to failure, with slightly increased sensitivity for decreased CNT content. In compression, a nonlinear and non-monotonic piezoresistive behavior was observed, with ?R initially decreasing in the elastic regime, leveling off at the onset of yielding and increasing after matrix yielding. The piezoresistive response of the composite is more sensitive to the CNT content for compression than for tension, and the calculated gage factors are higher in the compressive plastic regime. The results show that the piezoresistive signal is dependent on the CNT concentration, loading type and material elastoplastic behavior, and that recording ?R during mechanical loading can allow self-identification of the elastic and plastic regimes of the composite.

Key words: Polymer nanocomposites, piezoresistivity, carbon nanotube