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Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-2041-5786
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.ORCID iD: 0000-0002-8992-3623
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-1631-1781
2015 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 133, p. 179-186Article in journal (Refereed) Published
Abstract [en]

Polymeric hemicelluloses were extracted by autohydrolysis and alkali from a biomass feed consisting of the stems of rapeseed straw according to a full statistical factorial screening design. Water extraction yielded fractions rich in galactoglucomannan, while alkaline extraction yielded primarily xylan. The extracted galactoglucomannan and xylans had similar molecular weights, while the yield of xylan was higher than the yield of galactoglucomannan. The extracted hemicellulose fractions also contained some lignin (7-15%) and traces of Ca, K, Na, and Si. Free-standing films were prepared from the hemicellulose fractions with different xylan:galactoglucomannan ratios. The rapeseed xylan films showed strain-to-break values >60% without any added plasticizers.

Place, publisher, year, edition, pages
2015. Vol. 133, p. 179-186
Keywords [en]
Rapeseed/canola straw, Extraction, Autohydrolysis, Alkaline extraction, Xylan, Glucomannan, Film
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-175899DOI: 10.1016/j.carbpol.2015.07.023ISI: 000361920900024PubMedID: 26344270Scopus ID: 2-s2.0-84937926293OAI: oai:DiVA.org:kth-175899DiVA, id: diva2:870276
Funder
Swedish Research Council Formas, 2013-844
Note

QC 20151113

Available from: 2015-11-13 Created: 2015-10-26 Last updated: 2018-09-07Bibliographically approved
In thesis
1. Extraction of polymeric rapeseed straw hemicelluloses for renewable films
Open this publication in new window or tab >>Extraction of polymeric rapeseed straw hemicelluloses for renewable films
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Polymeric hemicelluloses with high molecular weight were extracted from rapeseed straw with a straight forward hydrothermal extraction method, evaluated and refined by statistical factorial screening design and ‘severity factor’ analysis. The influence of the extraction conditions, time, temperature and pH of the extraction liquid, on the composition, molecular weight, yield and properties was unveiled. The initial statistical screening design provided critical knowledge in how the extraction parameters affect yield, lignin and sugar composition as well as molecular weight of the extracts. A more elaborate extraction study which encompassed a greater temperature range and variation of the pH in the hydrothermal liquid combined with ‘severity factor’ modeling on the molecular weight of the extracts provided deeper insights of the effect of the extraction conditions. Water and acid extraction resulted in glucomannan rich extracts. Glucomannan isolated with acid was more degraded than the glucomannan isolated with water. From an environmentally perspective water extraction is preferred to obtain glucomannan due to the corrosive nature of acid. The molecular weight of the dissolved glucomannan during water extraction increased with temperature. Xylan was co-extracted at the higher extraction temperature. Alkaline extraction yielded an extract rich in xylan, where the total amount and the molecular weight of xylan increased with alkali charge. The xylan was more degraded at the highest temperature, 140 °C, and the highest alkali charge. All different extractions yielded co-extracted lignin, especially during high charge of alkali, but the straw was never fully delignified or the cellulose fibres liberated. Some extracts, selected from the statistical screening study, were utilized as raw materials for renewable plastic films.  The glucomannan films were very fragile, while the xylan films had remarkable strain-at-break of 60 – 80 % without any added plasticizer.

Place, publisher, year, edition, pages
Stockholm: Kungliga Tekniska högskolan, 2016. p. 55
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:16
Keywords
rapeseed straw/canola straw, hemicellulose, xylan, mannan, extraction, characterization, severity factor, hemicellulose film
National Category
Polymer Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-185737 (URN)978-91-7595-939-9 (ISBN)
Presentation
2016-05-20, K2, Teknikringen 28, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council Formas, 2013-844
Note

QC 20160428

Available from: 2016-04-28 Created: 2016-04-26 Last updated: 2016-04-28Bibliographically approved
2. Biopolymers and materials from rapeseed straw biorefining
Open this publication in new window or tab >>Biopolymers and materials from rapeseed straw biorefining
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Rapeseed straw was fractionated through a hydrothermal process into its hemicellulose, lignin and cellulose components. In the first step, hemicellulose-rich fractions were extracted. Xylan-rich fractions with high molecular weight, 30,000 – 50,000 g/mol, were obtained at 110 °C and 1.5 M NaOH. Neutral and acidic conditions yielded extract rich in glucomannan with co-extracted xylan and lignin.After hemicellulose extraction, the straw was subjected to a soda cooking step where the straw was delignified and lignin solubilized. Two cooking times were evaluated in this step. A longer cooking time resulted in a lignin-rich precipitate and a cellulose pulp with a lower content of lignin compared with the shorter cooking time. Analysis showed rapeseed straw lignin consists of syringyl and guaiacyl aromatic structures. Peroxide bleaching of the pulp decreased the lignin content in the cellulose pulp further. Cellulose nanoparticles (CNF and CNC) were isolated from the bleached pulp. The CNF fraction was heterogenous in size while the CNC fraction was more homogenous in size with rod like aspects. Both were highly crystalline, with good thermal stability and high aspect ratio.Thin free-standing films of xylan were cast from water solution with mechanical integrity and very high strain-at-break > 80% even without added plasticizer.A surface modification process was developed where xylan was first pre-activated in alkali. This was followed by an etherification coupling reaction with glycidyl methacrylate and subsequently grafted by interfacial free radical graft polymerization with octadecyl acrylate chains. The resulting grafted xylan became hydrophobic and gained a thermoplastic behavior. It was blended with PCL matrix via melt-extrusion. The grafted xylan was homogeneously distributed within the biocomposite and the PCL matrix was reinforced while at the same time preserving the ability to elongate to tensile strains > 500%. Analogous biocomposites with unmodified xylan in a PCL matrix resulted in heterogenous mixtures and brittle tensile properties.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. p. 89
Series
TRITA-CBH-FOU ; 2018:38
Keywords
Rapeseed/canola straw, biorefinery, hemicelluloses, lignin, cellulose, cellulose nanoparticles, films, grafting, thermoplastic, biocomposites, rapshalm, bioraffinaderi, hemicellulosa, lignin, cellulosa, cellulosa nano partiklar, hemicellulosafilm, ympning, termoplastisk, biokompositer
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-234656 (URN)978-91-7729-913-4 (ISBN)
Public defence
2018-10-12, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180912

Available from: 2018-09-12 Created: 2018-09-07 Last updated: 2018-09-12Bibliographically approved

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Svärd, AntoniaBrännvall, ElisabetEdlund, Ulrica

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