Hybrid Reinforcement of Carboxymethyl Cellulose Films with Nanocellulose, Bentonite, and Ceramic Industry Waste: Structural, Thermal, and Morphological Characterization

Abstract

In this study, biodegradable hybrid polymeric films were developed by reinforcing a carboxymethyl cellulose (CMC) matrix with nanocellulose (NC), bentonite, and ground fired ceramic waste recovered from the vitrified ceramic industry. Seven formulations were prepared by the solvent casting method, and their structural, thermal, thermomechanical, and morphological properties were characterized by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA/DTGA), dynamic mechanical analysis (DMA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). DSC analysis revealed endothermic peaks at 240–248 °C corresponding to the onset of thermal degradation, while DTGA curves showed a two-stage degradation behavior for all formulations. The incorporation of inorganic reinforcements markedly improved thermal stability: the temperature at 10% mass loss (T10%) increased from 150 °C for pure CMC to 207 °C for the ceramic-waste-containing films, and the highest T50% value (397 °C) and char yield (40.2%) were recorded for F7 (80% CMC, 10% NC, 10% ceramic waste), confirming a thermal barrier effect. DMA results showed that F4 (85% CMC, 10% NC, 5% bentonite) exhibited the highest storage and loss modulus values, whereas excessive bentonite loading reduced stiffness through agglomeration. FT-IR spectra indicated that interactions between the components were governed by hydrogen bonding and physical mixing rather than covalent bonding, and SEM-EDX analyses revealed more homogeneous filler dispersion at low loading levels. Accordingly, F4 and F7 were identified as the optimum formulations for dynamic mechanical stiffness and thermal stability, respectively.