Cellulose–lignin blends are proposed as alternative precursors for carbon fiber (CF) production, offering a potential sustainable and cost-effective alternative to the expensive fossil-based polymers currently used. The characteristics of the precursor fibers including their crystallinity, the incorporated chemical structures and the distribution of the biopolymers have a significant influence on their carbonization behavior and the properties of the CFs. They are partly determined by the composition of the bio-based resources and the conditions used during the fiber fixation, i.e. the coagulation, an important processing step. In this work, 13C solid and 2D solution NMR methodologies were applied to investigate the impact of coagulation and thermostabilization conditions on cellulose and cellulose-lignin blends using a thin film model. Solid state NMR spectroscopy showed that the choice of the anti-solvent influenced the proportion of cellulose II versus amorphous regions in the coagulated films. Independent of the presence of lignin, the choice of anti-solvent seems to impact the rate of thermal reactions. After thermostabilization at 245 °C, the samples were investigated using a solution NMR protocol devised for cellulosic materials. At 275 °C, most of the samples became insoluble for solution NMR. However, solid state NMR revealed further changes in the chemical composition, which were dependent on both the presence of lignin and the choice of anti-solvent. This multi-faceted approach combining solid state and 2D solution NMR techniques provides a comprehensive understanding of the cellulose structure and the products formed for cellulose-lignin-based CFs, which is crucial for optimizing their properties and potential applications.

中文翻译：

---

基于 NMR 的方法在研究木质素和纤维素对生物基碳纤维生产的行为中的应用


纤维素-木质素共混物被提议作为碳纤维 （CF） 生产的替代前体，为目前使用的昂贵的化石基聚合物提供了一种潜在的可持续且具有成本效益的替代品。前驱体纤维的特性，包括其结晶度、掺入的化学结构和生物聚合物的分布，对其碳化行为和 CF 的性能有重大影响。它们部分取决于生物基资源的成分和纤维固定过程中使用的条件，即凝结，这是一个重要的加工步骤。在这项工作中，应用了 13C 固体和 2D 溶液 NMR 方法，使用薄膜模型研究了凝结和热稳定条件对纤维素和纤维素-木质素混合物的影响。固体 NMR 波谱表明，抗溶剂的选择会影响凝固膜中纤维素 II 与无定形区域的比例。与木质素的存在无关，抗溶剂的选择似乎会影响热反应的速率。在 245 °C 下热稳定后，使用为纤维素材料设计的溶液 NMR 方案研究样品。在 275 °C 时，大多数样品变得不溶于溶液 NMR。然而，固体 NMR 揭示了化学成分的进一步变化，这些变化取决于木质素的存在和抗溶剂的选择。这种结合固态和 2D 溶液 NMR 技术的多方面方法提供了对纤维素结构和纤维素-木质素基 CF 形成的产物的全面理解，这对于优化其性能和潜在应用至关重要。