The Optimization of the Steam-Heat-Treated Process of Rattan (Calamus simplicifolius) Based on the Response Surface Analysis and Its Chemical Changes

The objective of this study is to investigate the impacts of steam heat treatment parameters (e.g., temperature, time, and pressure) on the impact toughness of rattan (Calamus simplicifolius). The Box–Behnken design response surface analysis was employed to optimize the steam heat treatment parameters. Impact toughness was selected as the evaluation index, with single-factor tests conducted as a baseline for comparison. Changes in chemical composition, cellulose crystallinity, and pyrolysis properties were analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, Thermogravimetry–Fourier transform infrared (TG-FTIR) spectra, and wet-chemistry methods for both untreated control samples and the heat-treated samples. The results show that a 1 h steam heat treatment at 160 °C under 0.1 MPa pressure has the optimal process parameters for the rattan. The achieved impact toughness value closely matches the predicted value at 71.29 kJ/m2. After the steam heat treatment, hemicellulose and cellulose contents decrease, whereas relative lignin content increases significantly, leading to improved toughness characteristics in Calamus simplicifolius samples. The TG results indicate that maximum weight loss occurs at temperatures of 352 °C, 354 °C, and 361 °C, respectively, for three different samples. This suggests that the thermal stability is enhanced as a result of the heat treatment. These findings will help optimize the heat treatments of the rattan material.