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Molecular dynamics of poly(vinyl alcohol)/cellulose nanofibrils nanocomposites highlighted by dielectric relaxation spectroscopy

Ghorbel, Nouha, Kallel, Ali, Boufi, Sami
Composites 2019
Fourier transform infrared spectroscopy, cellulose nanofibers, dielectric properties, differential scanning calorimetry, mixing, molecular dynamics, nanocomposites, polyvinyl alcohol, spectral analysis, temperature
The main focus of this work is the investigation of dielectric properties of nanocomposites based on poly(vinyl alcohol) (PVA) matrix and cellulose nanofibrils (CNFs) reinforcement. Nanocomposites films with different CNFs content were prepared by simple mixing of PVA solution and CNFs suspension in water and water evaporation.Dielectric spectroscopy of the nanocomposite’s films over a large temperature domain between -50°C to 170°C and a frequency range of 0.1 Hz to 1MHzwas studied to probe the molecular mobility and interfacial transition of the material. In addition, differential scanning calorimetry (DSC) and spectroscopic analysis by FTIR and Raman were performed to further evidence interaction between CNFs and PVA matrix. Different relaxations were detected, namely β andαrelaxations, water polarization and interfacial polarization known as Maxwell-Wagner-Sillars polarization (MWS), with magnitude and position being dependent on the CNF content.