The exact mechanism behind the disintegration of chemical pulp fiber into cellulose nanofibers is poorly understood. In this study, samples were subjected to various homogenization cycles, indicating that the mechanism is a stepwise process. In the earlier stages of the mechanical process, a large amount of macrofibrils were created as the larger structures disappeared. Upon mechanical treatment these macrofibrils disappeared despite the increasing yield of cellulose nanofibers. The proposed model expands the understanding of the disintegration pathway and may provide additional insight as to how wood cells are converted into microfibrils.

The characteristics of two novel types of technical lignin, namely Ecohelix (EH) and CleanFlow black lignin (CFBL), isolated from two different pulping process side streams, were analyzed. EH and CFBL were analyzed in terms of general composition, chemical functionalities, molar mass distribution, and thermal stability. For comparison, two relevant types of commercially available lignosulfonate and kraft lignin were used. The results showed that EH contains a large amount of sulfonated lignin, together with carbohydrates and ash. As such, it can be considered a lignin-carbohydrate hybrid molecule. CFBL was found to contain 91.5% Klason lignin and the lowest amount of carbohydrates (0.3%). EH showed the highest content of aliphatic OH groups (5.44 mmol/g) and CFBL a high content of phenols (4.73 mmol/g). EH had a molecular weight of 31.4 kDa and a sufficient thermal stability. CFBL had the lowest molecular weight (M-w = 2.0 kDa) and thermal stability of all kraft lignins analyzed in this study. These properties highlighted that EH is a suitable building block for material development and that CFBL is a promising material for the production of biofuel and biochemicals.

To investigate the dispersibility of dried cellulose nanofibers (CNFs), various additions (glycerol, octanol, glycol, and sodium perchlorate) were added to CNFs prior to drying. Glycerol was the only species to show any significant effect on re-dispersibility. The sedimentation was slower, and the transmittance of the solution was comparable to that of its undried counterpart. Increasing the amount of glycerol showed a clear trend with regard to dispersibility. The mechanical properties of films were maintained for samples that were dried and redispersed in the presence of glycerol.

A series of optically transparent composites were made by using tunicate cellulose membranes, in which the naturally organized cellulose microfibrillar network structure of tunicate tunics was preserved and used as the template and a solution of glycerol and citric acid at different molar ratios was used as the matrix. Polymerization through ester bond formation occurred at elevated temperatures without any catalyst, and water was released as the only byproduct. The obtained composites had a uniform and dense structure. Thus, the produced glycerol citrate polyester improved the transparency of the tunicate cellulose membrane while the cellulose membrane provided rigidity and strength to the prepared composite. The interaction between cellulose and polyester afforded the composites high thermal stability. Additionally, the composites were optically transparent and their shape, strength, and flexibility were adjustable by varying the formulation and reaction conditions. These composites of cellulose, glycerol, and citric acid are renewable and biocompatible and have many potential applications as structural materials in packaging, flexible displays, and solar cells.

The hemicellulose xyloglucan can be utilized to measure exposed cellulose surfaces for pulp fibers. This was shown by correlating a refining series with the adsorbed amount of xyloglucan, and by swelling cellulose fibers to various degrees by increasing the charge density. The method is specific to cellulose and could be used to quantify refining or to determine hornification.

Lignin has a very complex structure, and this is partly due to the monomers being connected by many different types of covalent bonds. Furthermore, there are multiple covalent bonds between lignin and polysaccharides in wood, and it is known that the structure of lignin covalently bound to the hemicellulose xylan is different to lignin bound to the hemicellulose glucomannan. Here, synthetic lignin (DHP) is synthesized at different pH and it is shown that lignin made at lower pH has a structure more similar to the lignin bound to xylan, i.e., having higher relative content of beta-O-4 ethers. It is hypothesized that xylan due to its carboxylic acids forms a locally lower pH and thus "direct" the lignin structure to have more beta-O-4 ethers. The biological significance of these results is discussed.

In a recent study, it was suggested that there could be direct associations between cellulose and lignin in mild alkaline cooked pulps. The observation was based on studies showing that the molecular straining of lignin was similar to that of cellulose. This finding has serious ramifications for technical production of pulps as it could expand on what is known about recalcitrant lignin removal during pulping. Herein, we investigate the possible interaction between cellulose and lignin discussing possible mechanisms involved at the nano-and molecular-scales, and present support for that the removal of hemicellulose by hot water extraction or mild kraft pulping causes strong interactions between lignin and cellulose.