Eva González Carmona: Sustainable, semi-continuous and closed-loop production of regenerated cellulose films

Abstract: 

Plastics are an integral part of our everyday lives due to their wide applicability, durability, and cost-effective production. However, many plastic products, especially flexible packaging, are used only once and then discarded. The short lifespan of plastics and their limited recyclability have become an increasing environmental threat by contributing to the depletion of fossil resources and the pollution of aquatic environments.

New policies and regulations are emerging to address and mitigate these challenges while simultaneously encouraging the development of eco-friendly alternatives derived from renewable resources, such as cellulose.

The aim of this doctoral thesis was to develop a sustainable and closed-loop process, based on the Ioncell technology, for the production of cellulosic films. The influence of the technical process parameters and the characteristics of the cellulose solutions on the processability and properties of the films was investigated. Additionally, the recyclability of the produced films was evaluated.

The optimal semi-continuous process compatible with existing industrial operations, consisting of a continuous extrusion system with an independent and also continuous washing and drying line, resulted in homogeneous, thin, and transparent films with excellent mechanical properties. Furthermore, film recyclability was demonstrated by the production of recycled films and fibers through the same process. Over two cycles, these products exhibited mechanical properties comparable to those obtained from virgin pulp.

All films produced in this research are thinner and stronger than cellophane, their commercial counterpart, while exhibiting similar optical and barrier properties. Consequently, these films could be applied in the same applications as cellophane, such as packaging, membranes, or battery separators.

In conclusion, the results of this research are very promising and demonstrate the significant potential of these films to become a feasible, sustainable alternative to commercial films.

Keywords: cellulose, regenerated cellulose films, ionic liquid, dry-jet wet extrusion, recycling 

Opponent: Prof. Tatiana Budtova, ParisTech, France

Custos: Prof. Michael Hummel, Aalto University School of Chemical Engineering 

Link to electronic thesis: Thesis available for public display 7 days prior to the defence at Aalto University's public display page.

Link to the remote defense: LINK