Thermal decomposition of native cellulose: Influence on crystallite size

The thermal degradation behavior of crystalline cellulose has been investigated using thermogravimetry, differential thermal analysis, and derivative thermogravimetry in a nitrogen atmosphere. Three cellulose samples, Halocynthia, cotton, and commercial microcrystalline cellulose Funacel, were used in this study to analyze the influence on crystallite size. They all belongs to cellulose Iβ type and those crystallite sizes calculated from the X-ray diffractometry profiles by Scherrer equation were very different in the order Halocynthia > cotton > Funacel. The thermal decomposition of cellulose shifted to higher temperatures with increasing crystallite size. However, activation energies for the thermal degradation were the almost the same among the samples: 159-166 kJ mol−1. These results indicated that the crystal structure does not affect the activation energy of the thermal degradation but the crystallite size affects the thermal degradation temperature.