Non-covalent polyvinylpyrrolidone modification of multiwalled carbon nanotubes for interphase controlled TPU nanocomposites

Multiwalled carbon nanotubes (MWNTs) were dispersed in thermoplastic polyurethane (TPU) matrix using the solution casting method. A non-covalent functionalizer polyvinylpyrrolidone (PVP) was used to improve MWNTs dispersion in TPU matrix. Optical microscopy revealed improved MWNTs dispersion and smoother film morphology for TPU/PVP-m-MWNTs nanocomposites. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis reveal that unmodified MWNTs increase melting temperature and crystallinity. In addition, TPU/PVP-m-MWNTs exhibited intermediate melting temperature and crystallite order, suggesting modified interfacial interactions. Rheology results suggest the strong PVP and MWNT interfacial interaction from relaxation behaviour and enhanced viscosity in TPU/PVP-m-MWNTs solution compared with TPU/MWNTs solution. Creep compliance shows that MWNTs and PVP-m-MWNTs addition in TPU increases instantaneous compliance and accelerates time-dependent deformation. FTIR and Raman spectroscopy have established interactions between TPU and PVP-m-MWNTs, which confirms hydrogen bonding at the interface of TPU and PVP. AC impedance spectroscopy showed a percolation threshold of 0.9 wt.% for TPU/MWNTs and 2.5 wt.% for TPU/PVP-m-MWNTs. Thermogravimetric analysis (TGA) showed increased thermal stability for TPU nanocomposites. These results revealed the improved processability and properties of TPU nanocomposites by modifying the MWNTs non-covalently.