Preparation and characterization of corn cob cellulose acetate for potential industrial applications

Abstract

Background: Locally generated biopolymers are amenable to further processing to widen their industrial applications. The study was aimed at generating low-cost cellulose acetate from corn cob residue and its characterizations for potential applications in biopolymer industries. Methods: Cellulose was extracted from the corn cob residue using the sodium hydroxide method. Acetylation of the cellulose to obtain corn cob cellulose acetate was carried out by adding appropriate quantities of a glacial acetic and acetylating mixture of acetic anhydride and sulphuric acid. The corn cob native cellulose and corn cob cellulose acetate were characterized using scanning electron microscopy (SEM) to examine their morphology, Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD) for structural elucidation while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to investigate their thermal properties. Results: - Two corn cellulose acetate samples with degree of substitutions 1.87 and 2.65 for samples CDA and CA respectively were obtained. They had improved solubilities in some organic solvents compared to the corn cob cellulose. The SEM examination showed the surface of the corn cob native cellulose (NC) was smooth and had a regular bundle-like structure while acetylation destroyed the original cellulose structure. Cellulose acetate samples showed a cluster-like structure with different sizes and a rough flake-like surface. FTIR and XRD studies showed that acetyl groups substituted cellulose hydroxyl groups. While FTIR study showed that the cellulose acetates had sharp bands between 1728 cm-1 to 1733 cm-1 and around 1368 cm-1 wavenumber unlike the corn cob cellulose sample, the data generated from XRD study indicated that acetylation of the corn cob cellulose led to 47% and 77% decrease in the crystallinity of CDA and CA samples respectively. The thermal analysis data from DSC and TGA studies confirmed that the acetylation improved the corn cob cellulose's thermal stability as indicated by the degradation of cellulose acetate samples at higher temperatures. Conclusion: The study concluded that low-cost cellulose acetate generated from corn cob residue could be potentially employed as a renewable, biodegradable, biocompatible polymer for industrial applications.