Preparation and characterisation of biocomposite materials based on chitosan and banana peel powder: structure, morphological, and thermal stability

Abstract In this study, biocomposite films based on chitosan (CS) and banana peel powder (BPP) were prepared by solution casting with 1, 3, and 5 mass% BPP content. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were conducted to determine the structure and morphology of the prepared films, while TGA was conducted to evaluate the thermal stability. FTIR spectra of the biocomposites showed the shift in the –OH bonding along the 3235 cm −1 , suggesting a hydrogen bond interaction between the –OH, –NH from the neat CS and the –OH from the BPP. The XRD results further supported the hydrogen bond interaction, as the addition of BPP resulted in a decrease in the peak intensities and a shift to higher angles as the BPP loading was increased. This was attributed to the decrease in crystallinity of neat CS, caused by the change in the crystal structure of neat CS as the BPP particles penetrated the lattice structure. The SEM images of neat CS showed a smooth surface with cracks, while all the biocomposites showed no cracks. The addition of 1 and 3 mass% of BPP showed well-dispersed BPP aggregates embedded in the surface of CS, which further supported improved interfacial adhesion through the strong hydrogen bonding. The TGA results of the biocomposites showed lower thermal stability with the addition of BPP; the maximum degradation temperature decreased from 280 °C (neat CS) to 265 °C with the addition of 5 mass% BPP. This suggests that BPP disrupts the polymer chain movement within CS, which then leads to reduced crystallinity and thermal stability.