PI: Eva Malmström, KTH
PhD Student: Adrian Eliasson, KTH
Duration: 4 years starting spring 2021
It has previously shown that it is possible to anchor various polymers (chemically or by physiosorption) to a range of cellulose substrates1,2 and that the corresponding materials’ properties are influence by the chemical nature of the polymer grafts.3,4 For this project, we are particularly inspired by the results obtained when -caprolactone (PCL) was grafted from kraft pulp fibers to form PCL-g-pulp which could be mixed with neat kraft pulp and formed into sheets using a Rapid-Köthen sheet former.5 Interestingly, it was found that the grafted polymer made it possible to hot-press the sheets together, into laminates, without need for any matrix polymer. This suggests that there is substantial chain interaction between the grafted polymers on adjacent sheets – can these form sufficient domains to allow for thermoforming?
The purpose of the project is to investigate if sufficient mobility/shear-planes can be accomplished by the introduction of a minor amount of polymers The idea is that the added phase/domains should provide sufficient flow properties to allow for thermo-processing under relevant conditions (temperature, pressure and time) to result in stable lignocellulose-based materials. This study is proposed to be undertaken on substrates of various length scales (pulp fibres – nanofibrils) and by various chemical approaches.
Objectives ________________________________________________________________________________________________ _________
Scientific: Enhanced fundamental understanding (chemistry-structure-property relationships) on what governs thermoplasticization of lignocellulose-based materials.
Technical: Chemistries for covalent and non-covalent modification. Molecular characterization of polymer grafts and their spatial distribution on the substrate (chromatography, spectroscopy and scattering techniques). Processing protocols for assessing the thermoformable properties. Material characterization.
Description of how this project addresses the hypotheses in FibRe __________________________________________
The polymer modification can be directed to take place on the surfaces of fibres/fibrils or in the intermediate phase (also containing lignin). The proposed project aims to generate fundamental understanding that will help to corroborate or falsify both FibRe´s hypotheses.
1Carlmark, A.; Larsson, E.; Malmström, E. “Grafting of cellulose by ring-opening polymerisation – A review” Eur. Pol. J. 2012, 1646-1659
2Malmström E.; Carlmark, A. “Controlled grafting of cellulose fibres – an outlook beyond paper and cardboard” Polym. Chem. 2012,3, 1702-1713
3Engström, J.; Jimenez, A.; Malmström, E. ”Nanoparticle rearrangement under stress in networks of cellulose nanofibrils using in situ SAXS during tensile testing” Nanoscale 2020, 12, 6462-6471
4Engström J.; Benselfelt, T.; Wågberg, L.; D’Agosto, F.; Lansalot, M., Carlmark, A.; Malmström E. “Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state” Nanoscale 2019, 11, 4287-4302
5Bruce, C.; Nilsson, C.; Malmström, E.; Fogelström, L. “Paper-sheet biocomposites based on wood pulp grafted with poly(e-caprolactone)” J. Appl. Polym. Sci. 2015, DOI: 10.1002/APP.42039