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Wood hydrolysate Barriers
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-0626-0802
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Wood hemicellulose is an abundant but fairly unexploited renewable feedstock. Recent studies have shown that hemicelluloses have a large potential for use in the food packaging industry as a sustainable alternative to the conventional oxygen-barrier materials used today. Such hemicelluloses are the main components of wood hydrolysates (WH), which are released in large quantities in many forestry process side streams. Recovering these hemicellulose-rich WH fractions and turning them into food packaging materials would be beneficial from both, an environmental and an economic point of view. However, in the development of packaging materials for large-scale applications, the high production costs to obtain the highly purified hemicellulose and their high moisture sensitivity are considered to be the two main limiting factors.In this study, a selective choice of the upgrading conditions during the recovery of WH and the incorporation of layered silicate particles in WH-based films and coating formulations are used as tools to control and tailor the barrier and tensile performances of the materials, enabling the design of renewable oxygen-barrier materials that are cost-effective and with improved properties. The WH originated from the aqueous liquor from hardwood hydrothermal treatment and upgraded according to one of three alternative routes (ultrafiltration, ultrafiltration followed by diafiltration, and ethanol precipitation) resulting in hemicellulose-rich fractions with different structures, compositions, and properties, which in turn resulted in different performances in terms of mechanical and oxygen-permeability properties. WH in its crudest form gave rise to coatings with the best oxygen-barrier performance, higher than the oxygen-barrier performance of pure hemicellulose coatings. The addition of montmorillonite or talc layered silicates as mineral additives in the WH-based films resulted in better water-vapor-barrier properties, and considerably improved oxygen barrier performance at a relative humidity as high as 80 %. The application of the WH-based films was therefore extended to a wider range of relative humidity conditions.

Abstract [sv]

Hemicellulosorna utgör en rikligt förekommande men underutnyttjad förnyelsebar råvara. Hemicellulosorna har en stor potential att kunna användas som material i matförpackningar som ett hållbart alternativ till de konventionella syrgasbarriärer som används idag. Hemicellulosor är huvudkomponenter i vedhydrolysat (WH) som frisätts i stora mängder i många träindustriella processvattenströmmar. Att utvinna dessa hemicellulosa-rika WH-fraktioner och omvandla dem till förpackningsmaterial skulle vara fördelaktigt, från såväl ett miljömässigt som ett ekonomiskt perspektiv. I utvecklingen av förpackningsmaterial i stor skala utgör dock de höga produktionskostnader som renframställning av hemicellulosa kräver, samt deras höga fuktkänslighet, de två viktigaste begränsande faktorerna.I detta arbete har två strategier utarbetats och tillämpats för att kontrollera och skräddarsy barriär- och mekaniska egenskaper hos framställda WH-baserade film- och bestrykningsmaterial; selektiva uppgraderingsförhållanden samt inkorporering av skiktade silikatpartiklar. Dessa strategier möjliggör design av syrgasbarriärer som är kostnadseffektiva och har förbättrade egenskaper. Det WH som användes var ett processvatten från en hydrotermisk behandling av lövved. Tre olika upparbetningsstrategier tillämpades och jämfördes (ultrafiltrering, ultrafiltrering följd av diafiltrering, samt fällning i etanol) och de hemicellulosa-rika fraktioner som erhölls från respektive upparbetning skilde sig åt i struktur, sammansättning och egenskaper, vilket i sin tur resulterade i material med olika prestanda i fråga om mekaniska egenskaper och syrgasbarriärförmåga. Den minst upparbetade WH-fraktionen gav upphov till beläggningar med bäst syrgasbarriärförmåga, bättre än beläggningar baserade på renframställd hemicellulosa. En tillsats av mineraladditiv i form av montmorillonit-lera eller talksilikater i de WH-baserade filmerna resulterade i förbättrad ångbarriärförmåga och markant förbättra syrgasbarriärförmåga vid relativa luftfuktigheter så höga som 80%. Applikationsområdet för WH-baserade filmer kan därmed utökas till att gälla ett bredare fuktighetsintervall.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 43 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2012:50
Keyword [en]
wood hydrolysate, xylan, hemicellulose, layered silicates, oxygen barrier, packaging, film, coaing, birch.
National Category
Textile, Rubber and Polymeric Materials Composite Science and Engineering
URN: urn:nbn:se:kth:diva-104821ISBN: 978-91-7501-503-3OAI: diva2:567541
2012-10-29, E36, lindstedtsvägen 3, KTH, Stockholm, 13:00 (English)
Vinnova, 2009-04311

QC 20121113

Available from: 2012-11-13 Created: 2012-11-13 Last updated: 2012-11-13Bibliographically approved
List of papers
1. Wood Hydrolysate Barriers: Performance Controlled via Selective Recovery
Open this publication in new window or tab >>Wood Hydrolysate Barriers: Performance Controlled via Selective Recovery
2012 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 2, 466-473 p.Article in journal (Refereed) Published
Abstract [en]

Films and coatings were produced from a noncellulosic polysaccaride-rich wood hydrolysate (WH) and the resulting oxygen barrier performance was improved by a selective choice of upgrading conditions. The WH was obtained from process water in the hydrothermal treatment of hardwood and subjected to one of three alternative upgrading treatments, resulting in xylan-rich fractions with significant differences in structure, composition, and properties of the recovered WH fractions, which in turn had a major impact on their performance with respect to tensile and oxygen barrier properties. The WH in the least upgraded state, the crudest fraction, produced films with the best performance in terms of oxygen permeability and was superior to corresponding films based on highly purified hemicellulose.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2012
National Category
Biochemistry and Molecular Biology
urn:nbn:se:kth:diva-90911 (URN)10.1021/bm201518d (DOI)000300115900021 ()2-s2.0-84856915601 (ScopusID)

QC 20120306

Available from: 2012-03-06 Created: 2012-03-05 Last updated: 2015-04-14Bibliographically approved

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