Cross-Linkable Modified Nanocellulose/Polyester Resin-Based Composites: Effect of Unsaturated Fatty Acid Nanocellulose Modification on Material Performances

Unsaturated fatty acid (FA)-modified nanocellulose (m-NC) shows potential application in improving mechanical properties of unsaturated polyester/m-NC nanocomposites (UPe/m-NC). A polyester matrix is obtained by polycondensation of maleic anhydride and products of poly(ethylene terephthalate) depolymerization with propylene glycol. Two methods of NC modification are performed: direct esterification with oleic acid, linseed, or sunflower oil FAs, and esterification/amidation with maleic acid/ethylene diamine (MA/EDA) bridging group followed by amidation with methyl ester of FAs. Increases of stress at break in the ranges from 148.8% to 181.4% and from 155.8% to193.0% for UPe/m-NC composites loaded with 1 wt% of NC modified directly or via MA/EDA cross-linker, respectively, are obtained. Results of the modeling of tensile modulus, by using the Cox-Krenchel model, show good agreement with experimentally obtained data. The effect of FAs' cross-linking capabilities on the dynamic-mechanical and thermal properties of the UPe/m-NC is studied. Cross-linking density, modulus, and T-g of the nanocomposite show appropriate relation with the unsaturation extent/structure of NC modification