Ductile wood fiber-based materials through sonication and plasticization
Time: Fri 2025-03-14 10.00
Location: Kollegiesalen, Brinellvägen 8, Stockholm
Video link: https://kth-se.zoom.us/j/67603017310
Language: English
Subject area: Fibre and Polymer Science
Doctoral student: Adrian Eliasson , Ytbehandlingsteknik, Eva Malmström
Opponent: Professor Orlando Rojas, The University of British Columbia, Kanada
Supervisor: Professor Eva Malmström, Wallenberg Wood Science Center, Ytbehandlingsteknik; Professor Lars Wågberg, VinnExcellens Centrum BiMaC Innovation, Linné Flow Center, FLOW, Fiberteknologi, Wallenberg Wood Science Center; Professor Mikael S. Hedenqvist, Polymera material, Wallenberg Wood Science Center; Anders Brolin, Stora Enso AB; Professor Anette Larsson, Chalmers tekniska högskola
QC 20250218
Abstract
Today’s society is highly dependent on plastic materials having essentialqualities such as formability, but they have severe drawbacks like limitedrecyclability. Thus, it is highly desirable to find alternatives to these materials,especially for single-use applications as in the packaging industry. In recentyears, biopolymers such as cellulose have been of significant interest asalternatives for plastic.However, biopolymers are challenging as they are extracted from nature aspolymers with predefined length and chemical structure that are difficult tomodify. To improve moldability among other properties, biopolymers needmulti-step modifications, often requiring large quantities of chemicals and lossof desired inherent properties.Here, ultrasonication is used to increase the sorption of plasticizers, e.g., glycerolor urea, onto cellulose to increase the ductility of the materials. The ductilityincreases from 10% achieved for only sonicated materials to 40% for materialssonicated with glycerol. This is due to glycerol on the fiber’s surface whichreduces the capacity of forming strong fiber joints and causes slippage. This isevidenced by the stress-strain curves of the glycerol-plasticized materials, whichexhibit a region of plastic deformation not usually seen in paper-like materials.Furthermore, the effects of glycerol on fiber wall levels are observed throughboth scattering experiments and DMA. The scattering shows that the fiber in awater-free glycerol swollen state retains a state typical for water-swollen fibers.The trend is proportional to the glycerol content. The DMA shows a thermaltransition for the fiber wall level related to glycerol content. This thesisdemonstrates that ultrasonication of pulp in the presence of plasticizer impartsductility to the corresponding material which may hold promise for the future.The concept is reliant on the combinations of ultrasonication, plasticizer and theunique fines formed during ultrasonication.