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Title of the thesis: Dissolution and regeneration of cellulose: Towards plastic-free films via systematic engineering.

Thesis defender: Pauliina Ahokas
Opponent: Prof. Thomas Rosenau; BOKU university, Austria
Custos: Assistant Prof. Jukka Niskanen, Aalto University School of Chemical Engineering

Dissolution and regeneration of cellulose: Towards plastic-free films via systematic engineering

Fossil based plastics are a significant source of persistent waste and environmental harm, especially in packaging, where products are used only briefly but remain in nature for centuries and contribute to the growing micro‑ and nano-plastics problem. This doctoral thesis examines how biodegradable cellulose films can be developed to replace these plastics in demanding packaging applications. Although cellulose based materials are renewable and biodegradable, existing films do not always meet the flexibility and barrier property requirements of applications such as food packaging. The aim of the study was to improve the performance of regenerated cellulose films without compromising their biodegradability. The work investigated how the composition and molecular structure of the raw material, as well as the choice of plasticizers, affect the films’ strength, flexibility, and resistance to water vapor and oxygen. Non derivatizing solvent systems made it possible to preserve the natural biodegradability of cellulose while still tailoring film properties for specific applications. The goal was to develop solutions that allow cellulose based materials to genuinely compete with conventional plastics. The thesis is highly relevant in the context of sustainable materials research and the promotion of a circular economy. The work combines materials science, chemical engineering, and statistical modelling to provide a systematic framework for designing cellulose films for industrial needs. The findings show that hemicellulose rich pulps improve dissolution and mechanical properties, that blending pulps of different molecular weights allows predictable adjustment of film properties, and that combining plasticizers yields films with mechanical and barrier properties surpassing those of commercial cellophane. Predictive modelling revealed clear connections between raw material composition, processing and the final film properties. The results demonstrate that regenerated cellulose films can be designed to meet the requirements of modern packaging while preserving their biodegradability. The knowledge gained supports both the development of sustainable packaging materials and future research on cellulose blends and plasticizers. Overall, the thesis provides scientific foundations and practical tools for developing renewable materials and supports the transition toward a circular economy and bio based packaging solutions.
 

cellulose dissolution, cellulose regeneration, crystallinity, hemicellulose, linear regression modeling, mixture design, molecular weight, permeability, plasticization, pulp reactivity, rheology, tensile properties

Thesis available for public display 7 days prior to the defence at .

Contact information: pauliina.ahokas@vtt.fi