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Alginate with maleic anhydride grafted linseed oil as compatibilizer
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.ORCID iD: 0000-0003-2109-9591
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-1631-1781
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Linseed oil was graft modified with maleic anhydride and introduced into alginate by coextrusion,producing filaments which are targeted to work as interphase compatibilizersbetween alginate and hydrophobic matrices. Modified oil was produced by a straightforwardair catalyzed radical chemistry based grafting of maleic anhydride onto the oil backbone.Additional esterification with dodecanol was also investigated. The structures of the modifiedoils were verified with 2D-NMR. Modified oil was blended with alginate and extruded intoCaCl2 forming thin filaments with diameters in the 130 - 260 m range. The impact of oilintegration into the alginate filaments and the effects of various modification chemistries onthe filament tensile properties were assessed with special emphasis on stress-at-break andcompared to values predicted by an empirical model relating the ‘stress to alginateconcentration’-ratio to prevailing conditions during filament drawing. Analogous alginatefilaments were prepared with chloric-, oxalic- and phytic acid calcium salts for comparisonwith alginate-oil hybrids to reveal the induced impact, with respect to composition andcharge, on the tensile performance.

Keywords [en]
Filament, fiber, alginate, linseed oil, maleic anhydride
National Category
Polymer Chemistry
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-239159OAI: oai:DiVA.org:kth-239159DiVA, id: diva2:1263848
Funder
Swedish Research Council Formas
Note

QC 20181119

Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2019-05-29Bibliographically approved
In thesis
1. POLYMER EXTRACTION AND UTILIZATION OF BROWN ALGAL BIOMASS
Open this publication in new window or tab >>POLYMER EXTRACTION AND UTILIZATION OF BROWN ALGAL BIOMASS
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aquaculture is a field with a world changing potential. The areas at sea are enormous and aquatic cultivations impact both the environment and local ecology far less than land based cultivations. In the realm of algae, abundancies exists of nutrition, water and accessible sunlight, but there is constant shortage of places to dwell. In an algae farm, the algae are given free space to dwell on a seeding line, the growth is massive. In the Swedish research project Seafarm, which this work belongs to, a 4500 m long line gives 15 kg/m of Saccharina latissima brown algae in each harvest. This is a thesis on how to process the algal biomass and generate materials. The algal component alginate, which is a natural charged polymer, is the main thread along the entire thesis, both in the beginning, when focus lies on extraction and in the end when alginate materials are made.

In an algal extraction-study the impact of chelation-strength parameter was assessed. Salts with different ability to chelate ions were used in the extraction process, sodium citrate was found to be the most promising extraction salt to liberate alginate.

A cyclic process, in which a sodium citrate solution was regenerated and reused, was developed and assessed. An interesting effect of the new process was that it allowed for a fractionation of alginate into several qualities with different uronic acid composition (the two building blocks of alginate). This fractionation was scaled up to supply enough alginate to support a material study to evaluate the individual properties of the different fractions.

Alginate gel filaments were made by extruding alginate into calcium chloride solution, in which if forms gels. Certain gels were also exposed to aluminum chloride. The filaments were tested for their tensile properties. An interesting trend in the relation between gel strength and uronic acid composition also inspired a theoretical study to establish the mechanism behind the observed trends. Gel-filaments were drawn in solutions of different alginate interacting salts, then dried into thin filaments and subjected to tensile testing. The treatments increased the modulus of the filaments and also increased their stress-at-break. The tensile properties were comparable to that of other natural derived fibers such as hemp fiber or cotton cellulose.

Compatibilizers were developed to tune the surface energy of the filaments and approach that of polymers used in fiber reinforced composites. The compatibilizers were made of linseed oil that was grafted with maleic anhydride to attach charged groups. The graft modified oil was added to alginate filaments which were tensile-tested.

Abstract [sv]

Akvakultur har världsförändringspotential. Havets vidder är enorma och akvatiska odlingar påverkar miljön och den lokala ekologin långt mindre än jordbruket på land. I algernas domäner finns det rikligt med näring, vatten och tillgängligt solljus, men det är en konstant brist på fria ytor att växa på. När en algfarm förser algerna med utrymmet på ett helt rep och de får växa ostört, då växer det så det knakar. I det svenska forskningsprojektet Seafarm, som finansierat detta arbete, ger ett 4500 m långt rep 15 kg/m Saccharina latissima brunalger, vid varje skörd. Den här avhandlingen är en studie i algbiomassabearbetning och hur nya material av biomassan kan framställas. Alginat, som är en av algens beståndsdelar, och en naturlig laddad polymer, är den röda tråden genom hela avhandlingen, både i början, där fokus låg på extraktion och i slutet där olika alginatmaterial preparerades.

I en inledande studie undersöktes effekten av kelatering vid extraktionerna. Salter med olika jonkelateringsförmåga användes i extraktioner, och användningen av natriumcitrat visade sig vara mest fördelaktigt i extraktionslösningar för att utvinna alginat.

Med utgångspunkt i den inledande extraktionsprocessen utvecklades en ny cyklisk process då natriumcitratlösningen regenererades och återanvändes. Den nya processen utvärderades och en intressant effekt var att den möjliggjorde utvinning av alginat i flera olika fraktioner med olika uronsyrasammansättning (de två byggstenarna i alginat). Denna fraktionering skalades upp för att renframställa tillräckligt med alginat för att kunna testa fraktionerna in en materialstudie.

I materialstudien gjordes geltrådar genom att extrudera alginat ner i en kalciumkloridlösning, där de gelade. Några geler exponerades också för aluminiumklorid. Trådarna dragprovades och resultaten visade ett intressant samband mellan gelstyrka och uronsyrasammansättning vilket inspirerade oss till att göra en teoretisk studie för att klarlägga ursprunget till trenden.

Geltrådar gjordes också till tunna fibrer i en process där de först extruderades, sedan drogs ut i olika saltlösningar och slutligen torkades. När fibrerna dragprovades visade det sig att de hade hög elasticitetsmodul och hög dragstyrka. Dragstyrkan var i samma storleksordning som t.ex. hampafiber eller bomullsfiber.

En kompatibilisator utvecklades för att anpassa ytenergin hos alginatfibrerna och i en riktning att för att likna plaster som brukar fiberförstärkas. Kompatibilisatorn framställdes av linolja som ympades med maleinsyraanhydrid för att fästa laddade grupper på den. Denna nya komponent inkorporerades i fibrer tillsammans med alginat och fibrerna dragprovades.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 88
Series
TRITA-CBH-FOU ; 2018:58
Keywords
Algae, Saccharina latissima, alginate, brown seaweed, extraction, filament, chelation, gel
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-239160 (URN)978-91-7873-025-4 (ISBN)
Public defence
2018-12-07, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council Formas, 2013-92
Note

QC 20181119

Available from: 2018-11-19 Created: 2018-11-16 Last updated: 2019-06-03Bibliographically approved

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