The application of cellulose fibers with varieties of allomorphs is of much interest. However, the crystal structural changes of certain allomorphs during the wet chemistry process are often ignored. In this work, the recrystallization behavior of softwood pulp cellulose IIII back to cellulose Iβ with tg conformation by hydrothermal treatment at different temperatures is carefully evaluated and calculated. The treatment contributed to the distortion of crystallites and lower crystallinity including the formation of intermediate amorphous phase at 60 °C. Higher hydrothermal temperature (100 °C) resulted in the reversion to cellulose I (59.7%) as well as retention of 12.5% of cellulose III, suggesting the uncompleted recrystallization during the process. With the loosened fibril structure and more amorphous regions, the thermal stability of recrystallized cellulose I is significantly dropped, far below that of original cellulose I/III materials. This study may provide new thoughts on the industrial processing and application of the polymorphic cellulose materials.

中文翻译：

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水热处理纤维素 III 的再结晶行为：多晶型和结晶度的动态变化

具有多种同质异形体的纤维素纤维的应用备受关注。然而，湿化学过程中某些同种异形体的晶体结构变化往往被忽视。在这项工作中，针叶木浆纤维素 IIII 通过水热处理在不同温度下重结晶为具有 tg 构象的纤维素 Iβ 的重结晶行为被仔细评估和计算。该处理导致微晶变形和降低结晶度，包括在 60°C 下形成中间非晶相。较高的水热温度 (100 °C) 导致转化为纤维素 I (59.7%) 以及保留 12.5% 的纤维素 III，表明该过程中未完全重结晶。随着松散的原纤维结构和更多的无定形区域，重结晶纤维素 I 的热稳定性显着下降，远低于原始纤维素 I/III 材料。该研究可能为多晶型纤维素材料的工业加工和应用提供新的思路。