Selluloosan liukeneminen ja regenerointi: Kohti muovittomia kalvoja systemaattisen suunnittelun avulla

Fossil-based plastics, especially in the packaging sector, create significant environmental and health burdens. They lead to persistent waste, marine pollution, and the accumulation of micro- and nanoplastics in organisms. These impacts highlight the urgent need for renewable alternatives that combine functionality and sustainability. While cellulose-based materials offer a biodegradable option to replace fossil-based films, current films lack flexibility and barrier properties required for demanding applications such as food packaging. This thesis addresses these challenges by engineering regenerated cellulose films through systematic design strategies using non-derivatizing solvent systems, ensuring preservation of the unique cellulose backbone and its inherent biodegradability. Three complementary approaches were explored: 1) increasing material utilization via hemicellulose-rich kraft pulps; 2) enhancing mechanical performance through controlled pulp blending; and 3) improving film functionality predictably by systematic plasticizer mixing. These strategies enabled precise control over dissolution, rheology, and film formation, supported by predictive regression models explaining up to 98% of the property variation. Hemicellulose retention improved process efficiency and film strength, while mixture design enhanced elasticity and toughness through multi-level molecular effects. Plasticizer choice and optimization achieved up to 50% higher strength and barrier improvements of 89% (water vapor) and 93% (oxygen) compared to traditional glycerol-plasticized films, surpassing commercial cellophane benchmarks. Predictive regression models enabled a data-driven approach to material design. These findings demonstrate that regenerated cellulose films can be tailored to meet packaging requirements while remaining biodegradable and structurally faithful to native cellulose. This work provides a scalable pathway toward plastic-free films, aligning with global circular economy goals and advancing cellulose-based materials as viable replacements for certain conventional plastics.