Effect of cellulosic nanowhiskers on the performances of epoxidized acrylic copolymers

The aim of the present work is to synthesize new nanocomposites based on an acrylic polymeric matrix loaded with cellulose nanowhiskers (CNWs). The acrylic copolymer was prepared by free-radical copolymerization of two monomers widely used for coating applications, namely 2-ethylhexylacrylate (EHA) and glycidyl methacrylate (GMA) bearing epoxy moieties, while CNWs were extracted from ramie fibers by the means of acid hydrolysis. A series of nanocomposites with various CNW loadings were obtained by solvent casting and were further crosslinked by an UV-induced curing. The extent of the crosslinking was substantiated by Fourier transform infrared spectroscopy (FTIR) whereas morphological, thermo-mechanical as well as optical properties were evaluated before and after the crosslinking by Scanning Electronic Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Dynamical Mechanical Analysis (DMA) and Polarized Optical Microscopy (POM). Thus it was demonstrated that strong interactions occur between the polymeric matrix and CNW, contributing to a significant improvement of the thermal stability and mechanical properties of the nanocomposites. More importantly, nanocomposites exhibit at certain CNW loading interesting optical properties.