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Thermoset resins using technical lignin as a base constituent
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Institute of Technology.ORCID iD: 0000-0003-4226-8593
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The need to find sustainable paths for our society is imminent to tackle environmental concerns of today. The majority of all plastic materials are produced from crude oil but in the future a much larger portion must originate from renewable resources to address some of these problems. Aromatic molecules are often used when producing rigid and thermally stable polymeric materials but there are few natural sources for them. One is, however, the wood component lignin that is produced on a large scale from chemical pulping processes of biomass. Lignins aromatic structures could be an alternative for non-renewable aromatics in e.g. thermoset applications.

The heterogeneity of lignin does however present some problems in terms of e.g. dispersity, solubility, diverse functionality, and varying polymer backbone structure. To tackle these challenges, work-up of lignin and thorough characterization are important to be able to produce materials with predetermined, predictable, properties. Technical lignins have functional groups that can be utilized as chemical handles for further modifications required for different material systems e.g. phenols, aliphatic hydroxyls, and carboxylic acids.

This thesis focuses on how to utilize solvent fractionated, relatively well-characterized, LignoBoost Kraft lignin to produce thermoset resins by chemical modification and a crosslinking procedure. An efficient procedure to selectively allylate the phenolics, the most abundant functionality, of the lignin fractions has been developed and evaluated as well as a curing procedure using a thiol crosslinker and a thiol-ene reaction. The produced materials were analysed with regards to material properties, density, and morphology. The resins based on the selectively allylated lignin fractions were furthermore evaluated as a potential matrix for carbon fibre composites. It was shown that the material samples could be processed by pre-impregnating carbon fibres and form composite materials. The molecules of the lignin fraction were also used as core substrates in a ring-opening polymerization to produce functional star co-polymers. The procedure was evaluated and it could be shown that the lignin backbone was subjected to substantial structural changes of lignin inter-unit linkages.

Lignin being one of the few large resources of naturally occurring aromatics has a big potential to be used for material applications where rigidity and thermal stability is important. This thesis attempts to add a few pieces towards such a goal.

Abstract [sv]

Behovet av att hitta hållbara tillvägagångssätt för vårt samhälle ökar hela tiden för att bemöta dagens miljöutmaningar. Större delen av alla plastmaterial tillverkas idag av råolja men i framtiden måste en mycket större del produceras från förnyelsebara råvaror för att hantera några av dessa problem. Aromatiska molekyler används ofta vid tillverkning av styva och termiskt stabila material, dock finns det få naturliga källor för sådana. En är emellertid träkomponenten lignin som produceras i stor skala i kemisk massatillverkning. Lignins aromatiska strukturer kan vara ett alternativ för icke-förnyelsebara aromatiska molekylära byggstenar i t.ex. härdplastsapplikationer.

Lignins heterogenitet ger upphov till vissa problem i termer av t.ex. dispersitet, löslighet, olika funktionalitet och varierande polymerskelettstruktur. För att hantera dessa problem är upparbetning av lignin och noggrann karaktärisering viktigt för att material med förutbestämda och förutsägbara egenskaper ska kunna tillverkas. Tekniskt lignin har funktionella grupper som kan användas som kemiska handtag för modifieringar som krävs för användning i olika materialsystem.

Denna avhandling fokuserar på hur lösningsmedelsfraktionerad, relativt välkarakteriserad, LignoBoost Kraftlignin kan användas för att producera termiskt härdande hartser genom kemisk modifiering och tvärbindning. Ett effektivt sätt att selektivt allylera ligninfraktionernas fenol-grupper, den vanligaste av de funktionella grupperna, har utvecklats och utvärderats såväl som en härdningsprocedur med hjälp av en tiol-tvärbindare och tiol-en-kemi. De producerade materialen analyserades med avseende på materialegenskaper, densitet och morfologi. Harts baserad på en av de selektivt allylerade ligninfraktionen undersöktes även som en potentiell matris för kolfiberkompositer. Det kunde påvisas att genom för-impregnering av kolfibrer kunde kompositmaterial tillverkas. Molekylerna i de olika ligninfraktionerna användes även som kärnor för att producera funktionella sampolymerer genom ringöppningspolymerisation. Det kunde påvisas att ligninets molekylära uppbyggnad blev kraftigt påverkat av tekniken då intramolekylära bindningar bröts upp.  

Lignin som tillhör en av de mycket få stora naturligt förekommande råvarorna för aromatiska strukturer har stor potential för användning i materialapplikationer där hög styvhet och termisk stabilitet är viktiga egenskaper. Den här avhandlingen försöker bidra med några pusselbitar mot ett sådant mål. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. , p. 57
Series
TRITA-CBH-FOU ; 2020:2
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-265010ISBN: 978-91-7873-402-3 (print)OAI: oai:DiVA.org:kth-265010DiVA, id: diva2:1377180
Public defence
2020-01-31, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation
Note

QC 2019-12-12

Available from: 2019-12-12 Created: 2019-12-11 Last updated: 2020-01-13Bibliographically approved
List of papers
1. Allylation of a lignin model phenol: a highly selective reaction under benign conditions towards a new thermoset resin platform
Open this publication in new window or tab >>Allylation of a lignin model phenol: a highly selective reaction under benign conditions towards a new thermoset resin platform
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2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 98, p. 96281-96288Article in journal (Refereed) Published
Abstract [en]

The lack of aromatic material constituents derived from renewable resources poses a problem to meet the future demands of a more sustainable society. Lignin is the most abundant source of aromatic structures found in nature and is a highly interesting source for material applications. Development of controlled chemical modification routes of lignin structures are crucial in order to further develop this area. In this study allyl chloride is used to selectively modify a lignin phenol in the presence of other lignin functionalities, i.e. aliphatic hydroxyls and conjugated alkenes, under mild reaction conditions in quantitative yields. For this, coniferyl alcohol was used as a model compound in the present study. The modification was carried out in ethanol as the synthesis media. Studies on the effect of reaction time and temperature revealed optimum conditions allowing for a quantitative yield without any detectable levels of byproducts as studied with NMR, FT-IR and FT-Raman. The thermal stability of the formed product was determined to be up to at least 160 degrees C through DSC measurements. In addition, as a proof of concept, the use of the allylated monomer to form crosslinked films using free radical thiol-ene polymerization was demonstrated.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-199018 (URN)10.1039/c6ra21447a (DOI)000385633100109 ()2-s2.0-84991578448 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20170119

Available from: 2017-01-19 Created: 2016-12-22 Last updated: 2019-12-11Bibliographically approved
2. Renewable Thiol-Ene Thermosets Based on Refined and Selectively Allylated Industrial Lignin
Open this publication in new window or tab >>Renewable Thiol-Ene Thermosets Based on Refined and Selectively Allylated Industrial Lignin
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2017 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 5, no 11, p. 10918-10925Article in journal (Refereed) Published
Abstract [en]

Aromatic material constituents derived from renewable resources are attractive for new biobased polymer systems. Lignin, derived from lignocellulosic biomass, is the most abundant natural source of such structures. Technical lignins are, however, heterogeneous in both structure and polydispersity and require a refining to obtain a more reproducible material. In this paper the ethanol-soluble fraction of Lignoboost Kraft lignin is selectively allylated using allyl chloride by means of a mild and industrially scalable procedure. Analysis using 1H-, 31P-, and 2D HSQC NMR give a detailed structural description of lignin, providing evidence of its functionalization and that the suggested procedure is selective toward phenols with a conversion of at least 95%. The selectively modified lignin is subsequently cross-linked using thermally induced thiol-ene chemistry. FT-IR is utilized to confirm the cross-linking reaction, and DSC measurements determined the Tg of the thermosets to be 45-65 °C depending on reactive group stoichiometry. The potential of lignin as a constituent in a thermoset application is demonstrated and discussed.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
Controlled refinery, Ethanol, Lignoboost Kraft lignin, Scalable procedure, Selective allylation, Thiol-ene thermoset
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-218122 (URN)10.1021/acssuschemeng.7b02822 (DOI)000414825900151 ()2-s2.0-85033478836 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20171124

Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2019-12-11Bibliographically approved
3. Transforming technical lignins to structurally defined star-copolymers under ambient conditions
Open this publication in new window or tab >>Transforming technical lignins to structurally defined star-copolymers under ambient conditions
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2019 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 21, no 9, p. 2478-2486Article in journal (Refereed) Published
Abstract [en]

Transforming biomass derived components to materials with controlled and predictable properties is a major challenge. Current work describes the controlled synthesis of starcopolymers with functional and degradable arms from the Lignoboost (R) process. Macromolecular control is achieved by combining lignin fractionation and characterization with ring-opening copolymerization (ROCP). The cyclic monomers used are epsilon-caprolactone (epsilon CL) and a functional carbonate monomer, 2-allyloxymethyl-2-ethyltrimethylene carbonate (AOMEC). The synthesis is performed at ambient temperature, under bulk conditions, in an open flask, and the graft composition and allyl functionality distribution are controlled by the copolymerization kinetics. Emphasis is placed on understanding the initiation efficiency, structural changes to the lignin backbone and the final macromolecular architecture. The present approach provides a green, scalable and cost effective protocol to create well-defined functional macromolecules from technical lignins.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-252978 (URN)10.1039/c9gc00835g (DOI)000468627300033 ()2-s2.0-85065578205 (Scopus ID)
Note

QC 20190814

Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-12-11Bibliographically approved
4. Lignin-Based Thermosetting Resins as a Renewable Material with Unexpected Morphology
Open this publication in new window or tab >>Lignin-Based Thermosetting Resins as a Renewable Material with Unexpected Morphology
(English)Manuscript (preprint) (Other academic)
Keywords
Lignin fractions, Aryl allyl ethers, Thiol-ene thermoset, Mechanical properties, Small- and Wide Angle X-ray Scattering
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-265154 (URN)
Available from: 2019-12-11 Created: 2019-12-11 Last updated: 2019-12-12Bibliographically approved

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The full text will be freely available from 2020-06-01 09:38
Available from 2020-06-01 09:38

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Jawerth, Marcus

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7891011121310 of 13
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