Defence Jesse Jongstra: "Synthesis, characterisation and application of bio-based polyester(amides) and polyester(imides) derived from waste sugar beet pulp"
Promotors: 1st promotor: Prof Patrizio Raffa, 2nd promotor: Prof Cor Koning, 3rd promotor: Prof Paolo Pescarmona
Abstract: This thesis focuses on bio-based polymeric materials derived from sugar beet pulp waste, using the monomer GalX to develop functional polymers with tuneable properties. Polyester(amide)s combine the strength of amide bonds with the degradability of ester linkages. By varying the ester-to-amide ratio, key material properties can be controlled. Higher amide content enhances thermal stability and increases the glass transition temperature, while higher ester content improves biodegradability. Although the materials are not readily biodegradable under the used experimental conditions, clear trends show that degradation behaviour can be adjusted through polymer composition. Similar trends are observed across different polymer systems, confirming that material properties can be tuned through composition. Materials with varying ester-to-amide ratios exhibit comparable thermal stability but differences in biodegradation, with higher amide content suppressing degradation. Polyester(imide)s based on citric acid-derived building blocks also show adjustable thermal properties, with degradation behaviour influenced by both monomer composition and the used diol. These polymers are applied in solvent-borne coatings with either ester or urethane cross-links. Coating performance strongly depends on cross-linking density, where higher cross-linker ratios improve network formation, solvent resistance, and hardness. Overall, these results demonstrate that sugar beet pulp-derived polymers offer a versatile platform for sustainable materials, with properties that can be tailored for applications such as coatings and systems requiring controlled, slow biodegradation.