Novel Improvements in Thermal and Hydrophobic Properties of Chitosan Reinforced by Rice Husk Ash

Abstract

Several bio-composites of chitosan (CS), as the hydrophilic natural polymer, were prepared by composition with 2, 5, 10 and 15 wt% of rice husk ash (RiHA), as the bio-based filler, via solution casting. These composites were obtained with the aim to improve the hydrophobicity, thermal stability, and degradation mechanism of pure chitosan. The resulting bio-composites were characterized by scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and FT-IR spectroscopy as well as XRD analysis. The SEM images showed amorphous morphology, irregular shape, and the number averaged size of 32 μm for the RiHA particles dispersed in the composites. Investigation of thermal properties of the RiHA-reinforced chitosan composites by TGA/DTG and DSC measurements has revealed some improvements in the thermal behavior of chitosan by the RiHA filler. For instance, the composite made of 15 wt% filler was found to be thermally more stable as it degrades at significantly higher temperatures than the composites containing other portions of the filler. Unlike the other samples that are degraded in three-steps, the weight loss of the composite having 15 wt% of RiHA occurs in two steps. Additional experiments showed that the composites are more hydrophobic than virgin chitosan and the hydrophobicity of the samples is increased by increasing their RiHA component.