Understanding the effect of lignin chemistry on the graphitic structure of lignin derived carbon fibres

碳纤维具有低密度、高强度和高刚性，因此可用于轻质材料，从而提高能源效率并节省燃料。然而，商业碳纤维的生产价格昂贵，目前依赖于石油基前驱体聚丙烯腈(PAN)和中间相沥青的使用。木质素是一种丰富的生物聚合物，可以作为一种低成本的可再生碳纤维前驱体。然而，迄今为止生产的木质素衍生碳纤维的强度和硬度是可变的，通常不足以满足大多数结构复合材料的应用。在这个项目中，我们将了解木质素的化学结构如何影响碳纤维中碳原子的排列，碳排列的形成机制以及由此产生的材料特性。这种结构-性质的相关性需要一种跨学科的方法，将木质素的化学分析与材料生产和分析相结合，以期从化学工程实践出发，设计出一种成本效益高的生产方法。前体纤维将被稳定、碳化，然后石墨化，以确定碳产率，并探索演变中的微观结构。材料性能将通过与OM/SEM横截面归一化的拉伸测试来测量。重要的是，将使用拉曼光谱和X射线衍射(重点是单纤维/少纤维X射线衍射法)详细研究碳纤维的新出现的石墨化结构，以将石墨化顺序与木质素化学相关联。鉴于影响碳纤维强度和硬度的因素多种多样，在该项目期间产生的大量数据集将使我们能够建立统计相关性，将聚合物化学效应与加工效应分开。

Carbon fibres have low density and high strength and stiffness and are hence used in lightweight materials, resulting in improved energy efficiency and fuel savings. However, the production of commercial carbon fibres is expensive and at present relies on the use of the petroleum-based precursors polyacrylonitrile (PAN) and mesophase pitch. Lignin is an abundant biopolymer and could be a low-cost renewable carbon fibre precursor. However, the strength and stiffness of lignin derived carbon fibres produced to date is variable and generally insufficient for most structural composite applications. In this project, we will understand how the chemical structure of lignin affects the arrangement of carbon atoms in the carbon fibres, the mechanisms by which the carbon arrangement forms and hence the arising material properties. This structure-property correlation requires an interdisciplinary approach that combines chemical analysis of lignin with materials production and analysis, with a view to chemical engineering practice, to design a cost-efficient production method. Precursor fibres will be stabilized, carbonized, and then graphitised to determine carbon yield, and explore the evolving microstructure. Material properties will be measured by tensile testing normalized to OM/SEM cross-sections. Importantly, the emerging graphitic structure of the carbon fibres will studied in detail using Raman spectroscopy and X-ray diffraction (with a focus on single/few fibre XRD) to correlate graphitic order with lignin chemistry. Given the variety of factors that can influence carbon fibre strength and stiffness, the large data set generated during this project will enable us to establish statistical correlations, separating the effect of polymer chemistry from processing effects.