Abstract
The potential of carbon nanotubes (CNT) as multifunctional filler in poly(epoxy)-based structural composites has been investigated. In a first step the reinforcement effect of CNT has been studied by tensile and three points bending tests, which evidenced significant improvements of stress and strain at break (respectively +17% and +30% for tensile tests on unidirectional carbon fibre-epoxy composites). Moreover, fracture experiments have also revealed a positive effect of CNT on the toughness (G1c) of carbon fibres-epoxy composites (+105% of improvement at the initial stage). In a second step, the health monitoring capability quantum resistive strain sensors (sQRS) made of CNT filled epoxy nanocomposite, incorporated in the core of glass fibres-epoxy composites has been studied. It was shown that during cyclic tensile tests, following the evolution of the relative resistance amplitude (Ar) of sQRS with strain gives a pertinent information on non-reversible phenomena such as plastic deformation and cracks’ development within the composite. In particular, the evolution of the sQRS sensitivity (gauge factor GF) under and over the elastic limit, allows to track damage accumulation throughout the composite. These results suggest a possible use of sQRS for the structural health monitoring (SHM) of composites in fields such as boating, wind energy, aeronautics and automotive.
Highlights
Quite early after their popularization by Iijma [1] in 1991, carbon nanotubes (CNTs) have raised hopes to improve polymers properties through the development of nanocomposites, due to their exceptional intrinsic properties [2,3,4]
Only slight changes of the epoxy matrix mechanical properties are seen, the most important being an improvement of 4% of the stress at break for the addition of 0.5% CNT
In a first part our results allowed us to show that the enhanced stress transfer ability of CNTs can improve the ultimate tensile strength and strain in traction and flexion of both bulk epoxy and UD carbon fiber laminates
Summary
Quite early after their popularization by Iijma [1] in 1991, carbon nanotubes (CNTs) have raised hopes to improve polymers properties through the development of nanocomposites, due to their exceptional intrinsic properties [2,3,4]. Nanocomposites can be used to design smart materials [22,23,24,25,26], provided that a special attention is paid to the dispersion of nanofillers in the polymer matrix, and to their further structuring into stable conductive networks If these conditions are fulfilled, the resulting Conductive Polymer nanoComposites (CPC) can meet many sensing applications for the detection of strain [27,28,29,30,31], temperature [32] and vapor [33,34,35]. In the boating, aeronautic, wind energy and automotive industries, the increasing use of structural composites have razed a need for the improvement of performances and the reliability of these materials In this context CNTs have revealed to be promising multifunctional nanofillers, able to simultaneously enhance mechanical properties [36,37,38,39,40], monitor the strain [41,42,43]
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