Effect of an encapsulate carbon nanotubes (CNTs) on structural and electrical properties of PU/PVC nanocomposites

Nanocomposites samples of polyurethane and polyvinyl chloride (PU/PVC) loaded both multi and single walled-carbon nanotubes were synthesized by the casting technique. The X-ray analysis indicated that decrease degree of crystallinity after addition of carbon nanotubes (CNTs) due to interaction between CNTs and PU/PVC. The Transmission electron microscope (TEM) indicated encapsulation of polymer blend on CNTs surface. The highest value of AC conductivity was observed at high content of CNTs and frequency related effective conductive network formed when CNTs loaded in the blend. Whereas molecules of CNTs bridged between localized states and potential barrier. The permittivity (ε′ε′) was decreased when the frequency increased due to direction dipoles of applied electric field. At high frequencies, the decreasing trend of permittivity seems nearly stable attributed to dipoles orientation. The higher value of dielectric loss (ε″ε″) was observed at low frequency due to the mobile charges within blend backbone. An increases of loss tangent (tan δ) with increasing in CNTs content was expected because conductivity increases with increasing CNTs. The decrease of tan δ with increasing frequency is attributed to the fact that the hopping frequency of charge carriers cannot follow any changes of externally applied electric field.