Rheological investigation of carbon-based hybrid polyurethane nanocomposites with continuous networks

Abstract

Carbon-based fillers were used as reinforcement for thermoplastic polyurethane (TPU) matrix. For the first time the rheological behavior of hybrid polyurethane nanocomposite has been surveyed and the formation of continuous network of two carbon-based fillers has been reported. Nanocomposites containing multi-walled carbon nanotubes (MWCNTs), carbon fibers (CFs) and MWCNTs/CFs were prepared through melt compounding method and evaluated with various techniques including microscopy, spectroscopy and comprehensive rheological analyses. Linear rheological methods such as strain, frequency, temperature and time sweeps, and non-linear flow curve method were adopted to study the viscoelastic properties of the nanocomposites. Attenuated total reflectance Fourier transform infrared spectroscopy showed that MWCNTs had higher interactions with TPU hard segments due to their high aspect ratio, whereas CFs had low interactions. In hybrid nanocomposite, a continuous network of carbon-based fillers was created which acted as a surface for nucleation of hard segment and induced the highest influence on viscoelastic behavior of resulting nanocomposites. Based on the microscopy analyses, existence of co-continuous morphology was observed for hybrid nanocomposite. Moreover, relationship between the structure of nanofillers and formation of microphase separated domains at various nanofiller contents was discussed. At first, the rheological behavior of each nanocomposite was separately studied. To conclude, the results corroborated that CFs and MWCNTs formed a network of carbon-based structure and changed the viscoelastic properties of hybrid nanocomposites.