Two different series of biobased polyethylene (BioPE) were used for the manufacturing of biocomposites, complemented with thermomechanical pulp (TMP) fibers. The intrinsic hydrophilic character of the TMP fibers was previously modified by grafting hydrophobic compounds (octyl gallate and lauryl gallate) by means of an enzymatic-assisted treatment. BioPE with low melt flow index (MFI) yielded filaments with low void fraction and relatively low thickness variation. The water absorption of the biocomposites was remarkably improved when the enzymatically-hydrophobized TMP fibers were used. Importantly, the 3D printing of BioPE was improved by adding 10% and 20% TMP fibers to the composition. Thus, 3D printable biocomposites with low water uptake can be manufactured by using fully biobased materials and environmentally-friendly processes.

2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl₂). The effect of two different concentrations of CaCl₂ (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl₂ led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices.

The capability of laccase from Myceliophthora thermophila to drive oxidative polymerization of Eucalyptus globulus Kraft lignin (KL) was studied as a previous step before applying this biotechnological approach for the manufacturing of medium-density fiberboards (MDF) at a pilot scale. This method, which improves the self-bonding capacity of wood fibers by lignin enzymatic cross-linking, mimics the natural process of lignification in living plants and trees. An interesting pathway to promote these interactions could be the addition of lignin to the system. The characterization of E. globulus KL after enzymatic treatment showed a decrease of phenolic groups as well as the aromatic protons without loss of aromaticity. There was also an extensive oxidative polymerization of the biomolecule. In the manufacture of self-bonded MDF, the synergy generated by the added lignin and laccase provided promising results. Thus, whenever laccase was present in the treatment, MDF showed an increase in mechanical and dimensional stability for increasing amounts of lignin. In a pilot scale, this method produced MDF that meets the requirements of the European standards for both thickness swell (TS) and internal bonding (IB) for indoor applications.

Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture sorption capacity and cytotoxicity, as preliminary tests for evaluating its suitability for wound dressing and similar applications. During the high-consistency enzymatic treatment it was found that only the treatment of the O₂-delignified pine pulp resulted in fibrillation into nano-scale. For 3D printing trials, the material needed to be fluidized further. By 3D printing, it was possible to fabricate various structures from the high-consistency enzymatic nanocellulose. However, the water sorption capacity of the structures was lower than previously seen with porous nanocellulose structures, indicating that further optimization of the material is needed. The material was found not to be cytotoxic, thus showing potential as material, e.g., for wound dressings and for printing tissue models.