Thermodynamic Toolkit for Chemical Recycling to Monomer
Time: Fri 2023-05-26 14.00
Location: F3, Lindstedtsvägen 26 & 28, Stockholm
Video link: https://kth-se.zoom.us/j/65895204148
Language: English
Subject area: Fibre and Polymer Science
Doctoral student: Linnea Cederholm , Fiber- och polymerteknologi, Wallenberg Wood Science Center
Opponent: Professor Louis Pitet, Hasselt University
Supervisor: Professor Karin Odelius, Polymerteknologi; Professor Minna Hakkarainen, Wallenberg Wood Science Center, Polymerteknologi; Doktor Peter Olsen, Wallenberg Wood Science Center, Biokompositer
QC 2023-04-27
Embargo godkänt av tf skolchef CBH Amelie Eriksson Karlström i mail 2023-04-26
Abstract
The design of polymeric materials for a circular economy is, to a largeextent, a challenge of thermodynamics. The work presented in this thesishas explored the thermodynamic features of ring-opening polymerizationand ring-closing depolymerization, to develop polymeric materials andrecycling strategies for chemical recycling to monomer.First, statistical copolymerization was explored as a tool for internal endcapping,in order to enhance the thermodynamic stability of an aliphaticpolyester. However, a drawback of the improved thermodynamic stabilitywas a negative impact on the recyclability. Next, the solvents effect on thethermodynamic equilibrium was studied. It was found that, apart from thedecreasing effect that dilution had on the ceiling temperature as aconsequence of the increased entropy, the properties of the solventstrongly influenced the equilibrium. This was studied for three differentsix-membered cyclic monomers, two lactones and one carbonate, whereceiling temperature of the more polar monomers where more influencedby the solvent effect. This solvent effect was used to realize chemicalrecycling to monomer of polylactide via ring-closing depolymerization,with high conversion and high selectivity. Finally, three different A–B–Atype block copolymers were designed. The influence of block componentson the mechanical properties and recyclability was investigated, showingthat the midblock chemical structure had a strong impact on the Young’smodulus, the elongation at break, as well as the on the ring-closingdepolymerization behavior.