Thermal and Mechanical Properties of Natural Rubber Composites Reinforced with Cellulose Nanocrystals from Southern Pine

There is currently a considerable interest in developing bio-based and green nanocomposites in industrial and technological areas owing to their biodegradability, biocompatibility, and environmental friendliness. In this study, a bio-based nanosized material, cellulose nanocrystals (CNC), extracted from southern pine pulp was employed as a reinforcing agent in a natural rubber (NR) matrix. NR/CNC nanocomposites were prepared by a solution mixing and casting method. The morphology, thermal, and mechanical properties of the nanocomposites were investigated using scanning electron microscopy, Fourier transform-infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermal gravimetric analysis, and differential scanning calorimetry. The CNC displayed a gradient dispersion in the nanocomposites, and no microscaled aggregates were observed. Both the tensile strength and modulus of the nanocomposites increased with the addition of CNC, accompanied by a slight decrease in elongation at break. The storage modulus also improved with the addition of CNC, which served as good evidence of the reinforcing tendency of CNC in the NR matrix. The thermal stability of the nanocomposites showed an insignificant decrease in CNC addition. The glass transition temperature of the nanocomposites was not influenced by CNC.