Comparative Research between Rhizome and Culm of Phyllostachys pubescens Based on Thermal Analysis

A systematic study was conducted on P. pubescens by analyzing thermal characteristics of its rhizome and culm (1.5 m) at different ages, using various analyses such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetry (TG). For both the rhizome and culm of P. pubescens, the relative crystallinity (Cr) of cellulose increased and then appreciably decreased with increasing age, but the rhizome contained about 10% less Cr than culm. However, the glass transition temperature (Tg) of culm (268.8 to 273.8 °C) was higher than in the rhizome (213.9 to 219.4 °C). The extrapolated initial decomposition temperature (Te) of 1-, 3-, and 5-year-old rhizome were 263.7 °C, 266.1 °C, and 263.9 °C, respectively; the Te of culms of the same age were 289.7 °C, 282.8 °C, and 283.4 °C, respectively. Variance analysis showed no significant differences in the Te of either rhizome or culm of different ages. Taking the chemical characteristics into consideration, it was concluded that the rhizome has a stable composition and good heat resistance.