Temperature and shear dependence of rheological behavior for thermoplastic polyurethane nanocomposites with carbon nanofillers

Multi-wall carbon nanotubes (MWCNTs), graphene nanoplates (GNPs), and hybrid fillers (MWCNTs/GNPs) filled thermoplastic polyurethane (TPU) nanocomposites are prepared via melt mixing. The effects of the fillers (contents of 1, 2, and 3 wt%), shear rate, and temperature are investigated on the rheological behavior of the TPU nanocomposites. The results demonstrate that the TPU/MWCNT nanocomposites exhibit stronger polymer filler and filler-filler interactions than the TPU/GNP and TPU/GNP/MWCNT nanocomposites, and the interactions are destroyed at higher shear rates. Anomalous rheological behavior is found in the nanocomposites with 2 and 3 wt% MWCNTs (2CNT and 3CNT) and 3 wt% MWCNTs/GNPs (3Hybrid). Specifically, as rising the temperature at higher temperatures (180-190 ?degrees C), the melt complex viscosities in the low frequency region (< 0.4 rad/s) are slightly increased for the 2CNT and 3Hybrid samples, and are more increased over a broader frequency region (< 10 rad/s) for the 3CNT sample. The Fourier transform infrared spectroscopy spectra demonstrate that the anomalous rheological behavior is not caused by hydrogen bonding in the TPU nano composites. It is revealed that the anomalous rheological behavior is attributed to stronger polymer-filler and filler-filler interactions in the nanocomposites, and the interactions are strengthened with rising temperature at higher temperatures.

Automated summary

In this study, MWCNTs, GNPs, and MWCNTs/GNPs filled TPU nanocomposites were prepared via melt mixing, and the effects of fillers, shear rate, and temperature on the rheological behavior of TPU nanocomposites were investigated. Results showed that nanocomposites with higher filler content exhibited anomalous rheological behavior at higher temperatures due to enhanced interactions between fillers and polymer.