## 4 L-MMCF Manufacturing Process
### Preparation of Feedback  
The feedstock for L-MMCF is any lignocellulosic material (i.e., comprised of holocell-lose (cellulose and hemicellulose), lignin, extractives, and ash), with the relative proportion of lignocellulosic content dictating the chemistry and conditions required for conversion to high alpha-cellulose suitable for L-MMCF production [71]. Regardless of the source, the fibres first need to be chipped or cut into consistently sized pieces to ensure evenness during the pulping process. The ideal wood chip size is 20 mm long by 4-5 mm thick, though chips 10-30 mm long and 3-6 mm thick are acceptable [36; 38]. Wood feedstocks can be processed with chip crushers, which are similar to decorticators utilised in hemp processing for manual separation of hurd from host fibre. Decortication is comprised of cutting (the equivalent of chipping), milling (the equivalent of debarking), and then screening to separate high cellulose past from lower-cellulose hurd. Chip crushing, or decortication for alternative agricultural feedstocks, allows for better penetration of cooking liqus in the dissolving pulp process. This is discussed further in Section 5. The feedstock is screened to remove contaminants, including particulate matter (e.g., dirt, rocks), fine particles \(<\) 2 mm in thickness, and irregular chips (i.e., knots, larger chips) [38; 72]. As shown in Table 2, industrial hemp bas can be utilised as a biomass resource for the L-MMCF process; additional research needs to be completed on hemp hurd to confirm suitability. Regardless of suitability, the bas and hurd components need to be separated to properly remove the hemi-cellulose, lignin, and extractive content, as bas fibre contains less hemi-cellulose and lignin than hurd (Table 2) and requires different pulping processing conditions. The feedstock should also be analysed prior to pulping for baseline characterisation. It will need to be reassessed throughout the L-MMCF manufacturing process to ensure the quality of the pulp and proper removal of contaminants. The characteristics assessed at this stage include:  
1. Carbohydrate content: * Alpha-, beta-, and gamma-cellulose in pulp: Alpha cellulose in undegraded pulp has a high molecular weight; beta cellulose is soluble in NaOH (S18), but can be precipitated when neutralised, and gamma cellulose remains soluble in the NaOH solution, even after neutralisation, and consists primarily of hemicellulose [73; 74]. Both hemicellulose (gamma) and amorphous cellulose (beta  
Figure 5: Flow diagram of L-MMCF processing steps, including end-use applications. cellulose, which may be the result of cellulose deterioration during the pulping process), are removed prior to solvent dissolution. * Alpha cellulose content: The L-MMCF spinning requires a very high alpha-cellulose content of more than 90% for L-MMCF fibre properties, such as tensile strength [17; 75]. As shown in Table 2, plant biomass has a much lower alpha cellulose content, requiring additional processing steps to acquire the higher percentage. * Hemicellulose: Gamma, or hemicellulose, should be less than 5% of the total cellulose content, based on dry weight to ensure a higher quality of pulp [76]. 2. Extractives: solvent and hot water-soluble components (e.g., fats, waxes, and terpenes), tannins, and inorganic salts. Extractive concentration can increase with the age of the feedstock (i.e., the older the plant, the more extractives are present) [77]. Extractives can lead to reduced strength and yellowing or discolouration in refined pulps [37; 77]. Generally, extractives do not survive the Kraft pulping process, though they do increase chemical consumption in cooking and can cause foaming issues in the pulping process, both of which are undesirable. Extractives content can be reduced by \"seasoning\" the chips in a pile for several months before feeding them into the mill, which is equivalent of hemp stalk retting.