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Wood hydrolysates- New concepts in renewable material design
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wood hydrolysates (WHs) are biomasses obtained in processes involving hydrothermal treatments of wood. WHs are rich in hemicelluloses and lignin. Instead of complicated extraction processes, such as precipitation, or extensive purification, this work utilizes the crude WHs. These WHs were successfully developed into oxygen-barrier films and coatings and a conceptual model was established to predict biomass matrix performance from molecular structures and interactions.

Free standing films and coatings from blends of WHs and either chitosan or carboxylmethyl cellulose (CMC) as a co-component, were produced. The films had an excellent oxygen-barrier performance which was even better than the corresponding films prepared from highly purified hemicelluloses. From a fundamental point of view, the Hansen solubility parameter (HSP) theory revealed the interactions between molecules in WHs, as well as in WH-based blends, which shed light on the great barrier performance of WH-based films. The hypothesis was that these strong interactions increased the mutual molecular affinity in the matrix, which led to a denser molecular packing and hence a good oxygen-barrier performance. The positron annihilation lifetime spectroscopy (PALS) measurements quantified the free volumes in the WH-based matrices. The HSP results, free volume size and distribution and thermal analyses supported the hypothesis well.

The HSP model was then used as a tool for designing oxygen-barrier coatings from WH-based blends. Using the HSP model, the interactions between different WHs and CMC were calculated and quantified. According to our hypothesis, the oxygen-barrier performance could thus be predicted. The free volume from PALS, oxygen permeability (OP) results were generally in consistence with the prediction from HSP model, which shows the potential of the HSP model for designing formulations of WHs for oxygen-barrier coatings for food packaging. 

To realize an industrially feasible and efficient process for WH-based barrier coating layers, some new approaches were attempted. Previously, coatings were prepared manually from WH-based blends. Now, a creative spray drying (SPD) coating technique was developed for a reproducible, efficient coating process of WHs with no additives or second components. Also, glyoxal crosslinking improved the ductility of the WH-based coatings which in turn improved the quality and oxygen-barrier performance of the coatings. Finally, scanning electron microscopy (SEM) integrated with a micro-tensile test device made it possible the real-time observation of coating surfaces during the deformation process. This can successfully analyze the mechanical performance of the coatings without being influenced by substrate.

In summary, the WHs present a viable and very promising resource for green barrier design.

Abstract [sv]

Hydrolysat är processvätskor från träindustrin. Istället för komplicerade utvinningsprocesser av ren hemicellulosa från processvätskor, används här det oförädlade hydrolysatet, som innehåller till största delen hemicellulosa och en del lignin. Den här avhandlingen beskriver hur vi framgångsrikt utvecklade detta hydrolysat till syrgasbarriärfilmer och bestrykningar som kan användas till matförpackningar samt hur modellering av strukturerna och interaktionerna mellan hydrolysatets komponenter kan förutsäga deras prestanda som barriärmaterial.

Fristående filmer och bestrykningar skapades från blandningar av vedhydrolysat och en samkomponent: antingen kitosan eller karboximetylcellulosa (CMC). Filmerna hade utmärkta syrgasbarriäregenskaper som till och med var bättre än filmer beredda av motsvarande renade hemicellulosa. Hansens löslighetsparametersteori (HSP) påvisade och kvantifierade interaktioner mellan molekylerna i både hydrolysat och hydrolysat-baserade blandningar vilket ger en förståelse för de goda barriäregenskaperna. Vår hypotes var att dessa starka interaktioner ökade affiniteten i matrisen vilket leder till tät molekylär packning och därmed bra syrgasbarriäregenskaper. Med Positron annihiliation lifetime spectroscopy (PALS) uppmättes de fria volymerna i de hydrolysat-baserade matriserna. HSP resultaten, storlek och fördelning av fri volym, samt termisk analys, verifierade hypotesen väl.

HSP-modellen användes sedan för att prediktera kompositionen hos syrgasbarriärbestrykningar från hydrolysat-baserade blandningar. Genom att använda HSP-modellen, kan interaktionerna mellan olika hydrolysat och CMC beräknas och interaktionerna i matrisen utvärderas. De fria volymerna uppmätta med PALS, syrepermeabilitet (OP)-resultaten var generellt överensstämmande med förutsägelserna från HSP-modellen, vilket visar potentialen för HSP- modellen som verktyg i formuleringen av barriärbestrykningarr för matförpackningar.

För att utveckla en industriellt realistisk och effektiv process för produktion av hydrolysat-baserade bestrykningar provades flera angreppssätt. Först gjordes bestrykningar manuellt från hydrolysat-baserade blandningar och dessa hade utmärkta syrebarriäregenskaper. Sedan utvecklades en spraytorkningsbeläggningsteknik (SPD) som en reproducerbar, effektiv bestrykningsprocess för hydrolysat utan tillsatser eller andra samkomponenter. Dessutom förbättrade töjbarheten hos bestrykningarna genom tvärbindning med glyoxal vilket i sin tur förbättrade kvalitet och syrgasbariäregenskaperna för bestrykningen. SEM integrerat med en dragprovutrustning gjorde det möjligt att i realtid observeraytan av bestrykningen under deformationsprocessen. Detta gjorde det möjligt att studera de mekaniska egenskaperna för beläggningarna utan inverkan av substratet.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , 74 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2013:26
Keyword [en]
wood hydrolysate, oxygen barrier, coatings, films, hemicellulose, lignin, CMC, chitosan, HSP, PALS, spray drying, SEM with tensile test, glyoxal crosslinking.
Keyword [sv]
vedhydrolysat, syrebarriäregenskaper, ytbeläggningar, filmer, hemicellulosa, lignin, CMC, kitosan, HSP, PALS, spraytorkning, SEM med dragprovning, glyoxal tvärbindning.
National Category
Polymer Technologies
Identifiers
URN: urn:nbn:se:kth:diva-122167ISBN: 978-91-7501-743-3 (print)OAI: oai:DiVA.org:kth-122167DiVA: diva2:621150
Public defence
2013-06-04, K2, Teknikringen 28, KTH, 100 44 Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Formas, 243-2008-129Vinnova, 2009-04311
Note

QC 20130515

Available from: 2013-05-15 Created: 2013-05-13 Last updated: 2013-05-15Bibliographically approved
List of papers
1. Barrier Films from Renewable Forestry Waste
Open this publication in new window or tab >>Barrier Films from Renewable Forestry Waste
2010 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 9, 2532-2538 p.Article in journal (Refereed) Published
Abstract [en]

Biobased free-standing films and coatings with low oxygen permeability were designed from a wood hydrolysate according to a recovery and formulation procedure that provides added value to wood converting industrial processes. Wood components released to the wastewater in the hydrothermal treatment of spruce wood were recovered and converted to an oligo- and polysaccharide-rich, noncellulosic fraction that was utilized in film formulations in a range of concentrations and compositions. Free-standing smooth and transparent films as well as coatings on thin PET were prepared and characterized with respect to oxygen permeability, tensile properties, structure, and water vapor transmission. With oxygen permeabilities as low as below I cm(3) mu m m(-2) day(-1) kPa(-1) and with adequate mechanical properties, the films and coatings show promising property profiles for renewable packaging applications.

Keyword
Added values, Barrier films, Bio-based, Films and coatings, Freestanding films, Hydrothermal treatments, Industrial processs, Low oxygen, Oxygen permeability, Packaging applications, Property profiles, Spruce wood, Transparent films, Water vapor transmission, Wood components, Agriculture, Coatings, Mechanical properties, Oxygen, Oxygen permeable membranes, Wastewater, Wastewater treatment, Water vapor, Wood
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-26701 (URN)10.1021/bm100767g (DOI)000281629600045 ()2-s2.0-77956536494 (Scopus ID)
Note
QC 20101129Available from: 2010-11-29 Created: 2010-11-26 Last updated: 2017-12-12Bibliographically approved
2. Conceptual approach to renewable barrier film design based on wood hydrolysate
Open this publication in new window or tab >>Conceptual approach to renewable barrier film design based on wood hydrolysate
2011 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 4, 1355-1362 p.Article in journal (Refereed) Published
Abstract [en]

Biomass is converted to oxygen barriers through a conceptually unconventional approach involving the preservation of the biomass native interactions and macromolecular components and enhancing the effect by created interactions With a co-component. A combined calculation/assessment model is elaborated to understand, quantify, and predict which compositions that provide an intermolecular affinity high enough to mediate the molecular packing needed to create a functioning barrier. The biomass used is a wood hydrolysate, a polysaccharide-rich but not highly refined mixture where a fair amount of the native intermolecular and intramolecular hernicelluloses-lignin interactions are purposely preserved, resulting in barriers with very low oxygen permeabilities (OP) both at 50 and 80% relative humidity and, considerably lower OPs than coatings based on the corresponding highly purified spruce hemicellulose, O-acetyl galactoglucomannan (AcGGM). The component interactions and, mutual affinities effectively mediate an immobilization of the chain segments in a dense disordered structure, modeled through the Hansen's solubility parameter concept and quantified on the nanolength scale by positron annihilation lifetime spectrum (PALS).

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-31287 (URN)10.1021/bm200128s (DOI)000289223500058 ()21366288 (PubMedID)2-s2.0-79953872797 (Scopus ID)
Note
Uppdaterad från submitted till published 20110506 QC 20110311Available from: 2011-03-11 Created: 2011-03-11 Last updated: 2017-12-11Bibliographically approved
3. Positron Lifetime Reveals the Nano Level Packing in Complex Polysaccharide-Rich Hydrolysate Matrixes
Open this publication in new window or tab >>Positron Lifetime Reveals the Nano Level Packing in Complex Polysaccharide-Rich Hydrolysate Matrixes
Show others...
2012 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, no 8, 3676-3681 p.Article in journal (Refereed) Published
Abstract [en]

Positron annihilation lifetime spectroscopy (PALS) was used to quantify the free volume and molecular packing in hydrolysate and hemicellulose-based barriers films, derived from process streams during wood processing operations. These hydrolysate films, comprising a fair share of lignin coexisting with poly- and oligo-saccharides, have very low but variable oxygen permeability but differ among themselves with respect to barrier performance as well as molecular weight, degree of branching, and monosaccharide residue main chain composition. From PALS measurements on hydrolysates, the free volume hole radius (r(h)), radius distributions (n(r(h))), volume-weighted hole sizes (<v(h)>(v)), and hole volume distributions (g(v(h))) were calculated showing that the hydrolysate matrixes are very densely packed with small holes. The results show a clear relationship between hydrolysate molecular architecture and composition, the nanolevel molecular packing, and the ability of suppressing the diffusion of oxygen through the film.

Keyword
Barrier performance, Degree of branching, Fair share, Hole radius, Hole size, Main chains, Molecular architecture, Molecular packings, Oxygen permeability, Positron annihilation lifetime spectroscopy, Positron lifetime, Process streams, Small Hole, Volume distributions, Wood processing
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:kth:diva-95094 (URN)10.1021/ac300152g (DOI)000302838500029 ()2-s2.0-84859887431 (Scopus ID)
Note

QC 20120515

Available from: 2012-05-15 Created: 2012-05-14 Last updated: 2017-12-07Bibliographically approved
4. Retrostructural model to predict biomass formulations for barrier performance
Open this publication in new window or tab >>Retrostructural model to predict biomass formulations for barrier performance
2012 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 8, 2570-2577 p.Article in journal (Refereed) Published
Abstract [en]

Barrier performance and retrostructural modeling of the macromolecular components demonstrate new design principles for film formulations based on renewable wood hydrolysates. Hardwood hydrolysates, which contain a fair share of lignin coexisting with poly- and oligosaccharides, offer excellent oxygen-barrier performance. A Hansen solubility parameter (HSP) model has been developed to convert the complex hydrolysate structural compositions into relevant matrix oxygen-permeability data allowing a systematic prediction of how the biomass should be formulated to generate an efficient barrier. HSP modeling suggests that the molecular packing ability plays a key role in the barrier performance. The actual size and distribution of free volume holes in the matrices were quantified in the subnanometer scale with Positron annihilation lifetime spectroscopy (PALS) verifying the affinity-driven assembly of macromolecular segments in a densely packed morphology and regulating the diffusion of small permeants through the matrix. The model is general and can be adapted to determine the macromolecular affinities of any hydrolysate biomass based on chemical composition.

Keyword
Molecular-Weight-Dependence, Positron-Annihilation, Films, Wood, Hydrolysate, Polystyrene, Lifetimes, Polymers, Matrices, Packing
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-101516 (URN)10.1021/bm300821d (DOI)000307422300041 ()2-s2.0-84865028395 (Scopus ID)
Note

QC 20120904

Available from: 2012-09-04 Created: 2012-08-30 Last updated: 2017-12-07Bibliographically approved
5. Innovative Approaches for Converting a Wood Hydrolysate to High-Quality Barrier Coatings
Open this publication in new window or tab >>Innovative Approaches for Converting a Wood Hydrolysate to High-Quality Barrier Coatings
2013 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 16, 7748-7757 p.Article in journal (Refereed) Published
Abstract [en]

An advanced approach for the efficient and controllable production of softwood hydrolysate-based coatings with excellent oxygen-barrier performance is presented. An innovative conversion of the spray-drying technique into a coating applicator process allowed for a fast and efficient coating process requiring solely aqueous solutions of softwood hydrolysate, even without additives. Compared to analogous coatings prepared by manual application, the spray-drying produced coatings were more homogeneous and smooth, and they adhered more strongly to the substrate. The addition of glyoxal to the aqueous softwood hydrolysate solutions prior to coating formation allowed for hemicellulose cross-linking, which improved both the mechanical integrity and the oxygen-barrier performance of the coatings. A real-time scanning electron microscopy imaging assessment of the tensile deformation of the coatings allowed for a deeper understanding of the ability of the coating layer itself to withstand stress as well as the coating-to-substrate adhesion.

Keyword
wood hydrolysate, hemicellulose, lignin, spray drying, coatings, real-time SEM, oxygen permeability, food packaging.
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-122166 (URN)10.1021/am401102h (DOI)000323875800017 ()2-s2.0-84883267826 (Scopus ID)
Funder
Vinnova, 2009-04311
Note

QC 20131004. Updated from manuscript to article in journal.

Available from: 2013-05-13 Created: 2013-05-13 Last updated: 2017-12-06Bibliographically approved

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