Mechanical and strain sensing properties of carbon nanotube reinforced epoxy/poly(caprolactone) blends

Abstract Mechanical and strain sensing behavior of polycaprolactone (PCL) epoxy blends reinforced with carbon nanotubes (CNTs) has been studied. It was observed that glass transition temperature generally decreases with PCL content while the effect of CNT is more complex, leading to an initial increase and then a sudden decrease when comparing to neat PCL/epoxy samples. It is explained by the increasing miscibility of PCL in the epoxy system, being more significant in presence of properly dispersed nanofillers, promoting a decrease of cross-linking degree. Concerning the mechanical behavior, CNT addition does not have an effective reinforcing effect, as expected, because of the increasing miscibility of PCL. In addition, PCL nanocomposites have a linear electrical response to applied strain, showing a high potential as sensors. Moreover, electrical sensitivity decreases with PCL content due to a higher deformation of PCL in comparison to epoxy matrix, corroborated by in situ microstructural characterization during mechanical tests, leading to a reduction in the tunneling distance between adjacent CNTs.