AbstractInterest in using kapok (Ceiba pentandra L.)–based cellulose in composite preparation is growing due to its advantages, including cost- effectiveness, light weight, non-toxicity, and biodegradability. In this study, chloroform, sodium chlorite, and sodium hydroxide were used for wax removal, delignification, and hemicellulose removal, respectively. It was observed that the air entrapment inside kapok fiber disappeared after it was treated with alkali. The structure became completely flattened and similar to a flat ribbon-like shape when examined using a vapour pressure scanning electron microscope (VPSEM). Fourier transform infrared (FTIR) spectroscopy was used to characterize the untreated and treated kapok fibers. The peak at 898 cm−1, which is attributed to the glucose ring stretching in cellulose, was observed for the obtained cellulose samples. Peaks corresponding to lignin (1505 and 1597 cm-1) and hemicellulose (1737 and 1248 cm-1) disappeared. The results of differential scanning colorimetry (DSC) indicated that the degradation of cellulose appeared as an exothermic peak at about 300 to 350 °C. The activation energy for thermal decomposition of kapok cellulose and its hemicelluloses was 185 kJ/mol and 110 kJ/mol, respectively. The activation energy for thermal decomposition can be used as an alternative approach to determine the purity of cellulose.