Sustainable Materials from Organosolv Fibers and Lignin, Kraft Fibers, and Their Blends

• Published in: Polymers 2024-01, Vol.16 (3), p.377
• Main Authors: Ruwoldt, Jost, Chinga-Carrasco, Gary, Tanase-Opedal, Mihaela
• Format: Article
• Language: English
• Subjects: Added-lignin thermoformed pulp; added-lignin thermoformed pulps; Analysis; Anatomy; Biomass; Cellulose fibers; Chemical processes; Contact Angle; Fiber length; Fibers; Fines content; green materials; High temperature; Hydrophobicity; Identification and classification; Kraft fibers; Kraft pulp; Lignin; Lignocellulose; Methods; Mixtures; molded pulp; Morphology; Moulded pulp; Organosolv; Organosolv fiber; organosolv fibers; Organosolv lignin; Paper products; Plastic pollution; Properties; Stiffness; Sulfuric acid; Surface morphology; Sustainable materials; Tensile Strength; thermoforming; Water resistance; Wetting
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym16030377

The aim of this study was to investigate new materials from organosolv fibers, organosolv lignin, kraft fibers, and their blends. The organosolv fibers showed reprecipitated lignin on the surface, a comparably low fiber length of 0.565 mm on average, and a high fines content of 82.3%. Handsheets were formed and thermopressed at 175 °C and 50 MPa, yielding dense materials (1050-1100 kg/m ) with properties different to that of regular paper products. The thermopressing of organosolv fibers alone produced materials with similar or better tensile strength (σ = 18.6 MPa) and stiffness (E* = 2.8 GPa) to the softwood Kraft reference pulp (σ = 14.8 MPa, E* = 1.8 GPa). The surface morphology was also smoother with fewer cavities. As a result, the thermopressed organosolv fibers exhibited higher hydrophobicity (contact angle > 95°) and had the lowest overall water uptake. Combinations of Kraft fibers with organosolv fibers or organosolv lignin showed reduced wetting and a higher density than the Kraft fibers alone. Furthermore, the addition of organosolv lignin to Kraft fibers greatly improved tensile stiffness and strength (σ = 23.8 MPa, E* = 10.5 GPa), likely due to the lignin acting as a binder to the fiber network. In conclusion, new thermopressed materials were developed and tested, which show promising potential for sustainable fiber materials with improved water resistance.