## 2 Cellulose Morphology
Regenerated cellululos are more stable than natural cellululos due to the Cellulose II structure having more intersheet hydrogen bonding [35; 47]. Crystallinity Index (CI) can be used to characterise cellulose quality and structure by quantifying the amount of crystalline material within a cellulose pulp solution; however, typical techniques, such as X-ray diffraction (XRD), do not account for amorphous regions of the cellulose, which can vary greatly depending on feedstock source [45; 48]. Regardless, CI can be utilised in the characterisation of various feedstocks and used as an indicator of cellulose quality, especially when considering end-use applications and when comparing samples within a subset by the same equipment. The CI of natural cellulose (100% hemp past and wood pulp) and regenerated cellulose (100% viscose and Lyocell hemp) fibres was determined by the authors using an XRD instrument (Bruker D8 Discover, CuK\(\alpha\) wavelength of 1.5418 A). The diffractogram data were collected at 1.5\({}^{\circ}\)/min scan speed with a step increment of 0.02\({}^{\circ}\). Results are illustrated in Figures 2 and 3. Figure 2: X-ray diffractograms of four different cellulose sources: two natural fibres (wood pulp and 100% hemp past) and two regenerated cellulosic fibres (100% viscose and lyocell hemp). Figure 2 displays the X-ray diffractogram of the natural and regenerated cellulosic fibres analysed. The two natural fibres (wood pulp and 100% hemp bast) exhibited similar diffraction patterns, with peaks centered at 20 = 14.8, 22.4, and 34.4\({}^{\circ}\), indicating a Cellulose I structure. The diffraction patterns of the two regenerated cellulosic fibres (100% viscose and lyocell hemp) resembled each other, with peaks positioned at 20 = 12, 20, and 21.5\({}^{\circ}\), indicating a Cellulose II structure. The slight left shift in the peak position for regenerated cellulose fibres compared to the natural cellulose fibres can be attributed to the processing of cellulosic fibres to turn these into regenerated cellulosic fibres [49]. The essential processing of regenerated cellulosic fibres can cause changes in the conformation of hydroxymethyl groups while the backbone conformation remains unchanged. Figure 3 displays the CI of the four cellulosic fibres calculated using the data shown in Figure 2. The peak height was used for the determination of CI for these four cellulose-based samples. The diffractogram data were processed using OriginPro(r) 2022 (OriginLab, Northhampton, MA, USA) and DIFFRAC.EVA V7 (Bruker, Ettlingen, Germany) software. The crystallinity index of the specimen was calculated by taking into account the area under crystalline and amorphous peaks using the equation below [48]. \[Crystallinity\ Index=\frac{Area\ under\ the\ crystalline\ peaks}{Total\ area\ under\ crystalline\ peaks\ and\ amorphous\ region}\]  
The average CI obtained ranged from 65 to 71%. As can be seen from Figure 3, the CI values of the two natural cellulosic fibres (100% hemp bast and 100% wood pulp) are comparable and do not differ significantly from one another (\(p\) = 0.275). On the other hand, the CI values of the two regenerated cellulosic fibres examined for this study--Lyocell hemp and 100% viscose--are comparable (\(p\) = 0.316) and substantially higher than those of the natural cellulosic fibres. The standard deviation on the CI obtained for the 100% viscose fibres is higher than for the other three fibres; it was attributed to the heavy crimp of the viscose fibres that affected the diffraction angle. Overall, the difference observed between the CI of the natural (Cellulose I) and regenerated cellulosic (Cellulose II) fibres indicate differentiation between the two polymorphs,  
Figure 3: Crystallinity index obtained from the X-ray diffractograms of four different cellulose sources (average of three replications). suggesting this type of analysis is useful for differentiation of different cellulose feedstocks based on fibre crystallinity.