Cellulose nanocrystals (CNCs) and nanofibrillated cellulose (NFC) are nanometer-sized particles and fibrils recovered from cellulosic substrates (wood pulp, microcrystalline cellulose…) by sulfuric acid treatment or mechanical disintegration, respectively. Owing to their high strength, modulus and aspect ratio, CNCs and NFC have the potential to significantly reinforce the mechanical properties of polymers, provided that the nanocrystals or fibrils are well dispersed in the polymer matrix and the filler-matrix interfacial adhesion is sufficient. Since the nanocellulose surface is highly hydrophilic, the reinforcement of hydrophobic matrices is challenging and requires the functionalization of the CNCs and NFC surface by appropriate functions, in order to control their dispersive and interfacial properties. In this context, we envisaged tuning the hydrophilic/hydrophobic balance at the CNCs and NFC surface by an original method based on the transesterification of vinyl acetate performed in water. The acetylation level was monitored by multi-esterification, i.e. by performing successive acetylation treatments on the same cellulosic substrate. The acetylated particles and fibrils were characterized by Fourier transform infrared (FT-IR), solid-state <sup>13</sup>C CP-MAS NMR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM). The reinforcing properties of esterified CNCs and NFC were subsequently investigated and compared, using naturel rubber as a model matrix. The impact of the esterification treatment and filler percolation on the nanocomposites properties will be particularly discussed through the comparison of the microscopic, thermal and mechanical data (TEM, TGA, DMA…)

Comparative study on the reinforcing properties in rubber of cellulose nanocrystals and nanofibrils functionalized in water

251st National Meeting (2016)

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