A Composite Fabrication Sensor Based on Electrochemical Doping of Carbon Nanotube Yarns

This work shows evidence of conventional liquid and polymer molecules doping macroscopic yarns made up of carbon nanotubes (CNT), an effect that is exploited to monitor polymer flow and thermoset curing during fabrication of a structural composite by vacuum infusion. The sensing mechanism is based o...

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Bibliographic Details
Published in:Advanced functional materials 2016-10, Vol.26 (39), p.7139-7147
Main Authors: Fernández-Toribio, Juan C., Íñiguez-Rábago, Agustín, Vilà, Joaquim, González, Carlos, Ridruejo, Álvaro, Vilatela, Juan José
Format: Article
Language:English
Subjects:
Adsorption
Carbon nanotubes
CNT fibers
composites
Curing
doping
Fibers
Infusion
Liquids
Polymer matrix composites
sensors
Yarns
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Summary:This work shows evidence of conventional liquid and polymer molecules doping macroscopic yarns made up of carbon nanotubes (CNT), an effect that is exploited to monitor polymer flow and thermoset curing during fabrication of a structural composite by vacuum infusion. The sensing mechanism is based on adsorption of liquid/polymer molecules after infiltration into the porous fibers. These molecules act as dopants that produce large changes in longitudinal fiber resistance, closely related to the low density of carriers near the Fermi level of bulk samples of CNT fibers, reminiscent of their low‐dimensional constituents. A 25% decrease in fiber resistance upon exposure to electron–donor radicals formed during epoxy vinyl ester polymerization is shown as an example. At later stages of curing the matrix undergoes shrinkage and applies a compressive stress to the fibers. The resulting sharp increase in electrical resistance provides a mechanism for detection of the matrix gel point. The kinetics of resistance change during polymer ingress are related to established models for macromolecular adsorption, thus also enabling prediction of polymer flow. This is demonstrated for vacuum infusion of a 150 cm2 glass fiber laminate composite, with the CNT fiber yarns giving accurate prediction of macroscopic resin flow according to Darcy's law. Macroscopic yarns made up of carbon nanotubes (CNTs) are doped by liquids/polymers entering their pores, producing large changes in fiber electrical resistance that follow kinetics of macromolecular adsorption. After calibration, a CNT yarn sensor can detect radical species and the gel point during epoxy curing, and predict polymer flow during fabrication of a 150 cm2 glass fiber laminate composite by vacuum infusion.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201602949