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Enhanced formability and mechanical performance of wood hydrolysate films through reductive amination chain extension
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-0626-0802
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-1631-1781
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2015 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 117, 346-354 p.Article in journal (Refereed) Published
Abstract [en]

An O-acetyl-4-O methylglucuronoxylan-rich wood hydrolysate (WH), generated by the hydrothermal treatment of hardwood, was chain extended using di- and tri-functionalized amino chain extenders through reductive amination. Chain extension was achieved via facile one- or two-step syntheses. The carbohydrate chain extension efficiency, molecular weights, and branching patterns were determined through a combination of SEC, 1HNMR, FUR and elemental analysis. The mild reaction conditions enabled an increase in the molecular weight while preserving the initial structures of the hemicelluloses. The chain extension strategy developed in this study was demonstrated to significantly improve the formability and mechanical performance of WH films, allowing for the water-casting production of coherent films with higher ratios of WH - 70-85% (w/w) - and reducing the need for co-components. Chain-extended WHs produced stronger and more ductile films than corresponding formulations prepared from unmodified WH. Films made from ethylenediamine chain-extended WH mixed with 30% (w/w) carboxymethyl cellulose showed a tensile strength of 62 MPa and a strain-to-failure of 3.3%. Additionally, chain-extended WHs produced films with an oxygen permeability as low as 0.2 cm(3) mu M m(-2) day(-1) kPa(-1) at 50% RH.

Place, publisher, year, edition, pages
2015. Vol. 117, 346-354 p.
Keyword [en]
Wood hydrolysate, Xylan, Reductive amination, Oxygen barrier, Packaging Film
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-160041DOI: 10.1016/j.carbpol.2014.09.067ISI: 000346263800044ScopusID: 2-s2.0-84908424370OAI: diva2:793338
VINNOVA, 2009-04311

QC 20150306

Available from: 2015-03-06 Created: 2015-02-13 Last updated: 2015-04-14Bibliographically approved
In thesis
1. Strategies for Renewable Barriers with Enhanced Performance
Open this publication in new window or tab >>Strategies for Renewable Barriers with Enhanced Performance
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Forest biomass is expected to play an increasingly important role in tomorrow´s global bio-economy as one of the main renewable sources of materials, chemicals and energy. In the framework of the biorefinery concept, the forestry industry is looking for new processes to utilize several fractions in the biomass (cellulose, hemicelluloses, lignin etc.), thereby generating value-added by-products, an economically sustainable process, and new market opportunities. The work presented in this thesis aims to develop oxygen barrier films and coatings based on the hemicelluloses-rich biorefinery fraction, referred to as wood hydrolysate (WH). These WHs were obtained from the aqueous process liquor after the hydrothermal treatment of hardwood. The WH-based films and coatings are intended to meet the increasing demand of bio-based and biodegradable barrier materials in multi-layered laminates for the food-packaging sector. This work has employed four strategies to provide control and enhancement of the mechanical and barrier properties of WH: I) a selective choice of up-grading pre-treatments of the WH aqueous liquor, II) the incorporation of layer silicates into the barrier formulation, III) chain-extension of the hemicellulose chains present in the WH via reductive amination, and IV) the development of wood hydrolysate polyelectrolyte complexes (PEC) with quaternized cellulose (QC). It has been demonstrated that the crude WH, with almost no upgrading pre-treatment, produced coatings with the best performance in terms of low oxygen permeability. Furthermore, the addition of naturally occurring layered silicates into the WH-based film formulations led to a decrease in water vapor permeability, and a considerably lower oxygen permeability at 80% relative humidity. Moreover, the chain-extension approach was shown to significantly enhance the formability and mechanical performance of WH-based films, making it possible to produce cohesive films with a higher proportion of WH, 70–85% (w/w) and to reduce the content of co-components in the films. The WH/QC-PEC-based films exhibited by far the best tensile properties, better than those previously obtained with carboxymethyl cellulose as a co-component in an equal amount, with a tensile strain-at-break as high as 7 %.

Abstract [sv]

Vedbiomassa väntas spela en viktig roll i framtidens bioekonomi som en förnybar råvara för material, baskemikalier och energi. Genom att betrakta skogindustriella processer som ett bioraffinaderi och utnyttja fler vedfraktioner i biomassan (cellulosa, lignin och hemicellulosor m.fl.) via nya processer och metoder kan mervärdesprodukter och en ekonomiskt hållbar process skapas och nya inkomstkällor och marknader genereras. Avhandlingsarbetes mål har varit att skapa barriärfilmer och –bestrykningar baserade på hemicellulosa-rika så kallade vedhydrolysat (WH), vattenbaserade fraktioner som generats vid hydrotermisk extraktion av lövved. De WH-baserade filmerna och bestrykningarna är avsedda att utgöra biobaserade och nedbrytbara barriärskikt i flerskiktade matförpackningslaminat. Avhandlingsarbetet har resulterat i fyra strategier som kontrollerar och förbättrar barriär- och mekaniska egenskaper hos WH: I) selektiv upprening av förbehandling av hydrolysaten, II) inblandning av skiktade silikatpartiklar i formuleringarna, III) kedjeförlängning av hemicellulosapolymererna i WH via reducerande aminering, samt IV) skapandet av polyelektrolytkomplex (PEC) mellan WH och katjonisk cellulosa (QC). 

Den WH som förbehandlades minst gav upphov till bättre syrgasbarriärer än WH som upprenades i högre grad. Tillsats av silikatpartiklar till filmformuleringarna resulterade i filmer med lägre permeabilitet för vattenånga och i synnerhet en förbättring av syrgasbarriäregenskaperna vid 80% relativ fuktighet. Kedjeförlängning förbättrade signifikant filmbildningsegenskaperna liksom de mekaniska egenskaperna vilket gjorde det möjligt att skapa koherenta filmer med en högre andel WH, 70 – 85% (w/w) och en lägre andel tillsats. PEC-baserade filmer uppvisade de överlägset bästa mekaniska egenskaperna, med en töjbarhet på upp till 7%, jämfört med tidigare WH-baserade filmer där lika delar karboxymetylcellulosa använts som tillsats.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. 69 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:17
Wood hydrolysate, xylan, birch, layered silicates, oxygen barrier, packaging, film, coating, reductive amination, chain-extension, cationic cellulose, polyelectrolyte complexes, hemicellulose, vedhydrolysat, xylan, björk, silikat, syrgasbarriär, förpackningar, film, bestrykning, reducerande aminering, kedjeförlängning, katjonisk cellulosa, polyelektrolytkomplex, hemicellulosa
National Category
Polymer Technologies Paper, Pulp and Fiber Technology Textile, Rubber and Polymeric Materials
Research subject
Fibre and Polymer Science
urn:nbn:se:kth:diva-164098 (URN)978-91-7595-510-0 (ISBN)
Public defence
2015-05-08, Kollegiesalen, Brinellvägen 8, Stockholm, 13:00 (English)
VINNOVA, 2009-04311

QC 20150414

Available from: 2015-04-14 Created: 2015-04-13 Last updated: 2015-04-14Bibliographically approved

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