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Extraction of polymeric rapeseed straw hemicelluloses for renewable films
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-2041-5786
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. , 55 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:16
Keyword [en]
rapeseed straw/canola straw, hemicellulose, xylan, mannan, extraction, characterization, severity factor, hemicellulose film
National Category
Polymer Chemistry
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-185737ISBN: 978-91-7595-939-9OAI: oai:DiVA.org:kth-185737DiVA: diva2:923274
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
List of papers
1. Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation
Open this publication in new window or tab >>Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation
2015 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 133, 179-186 p.Article 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.

Keyword
Rapeseed/canola straw, Extraction, Autohydrolysis, Alkaline extraction, Xylan, Glucomannan, Film
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-175899 (URN)10.1016/j.carbpol.2015.07.023 (DOI)000361920900024 ()26344270 (PubMedID)2-s2.0-84937926293 (ScopusID)
Funder
Swedish Research Council Formas, 2013-844
Note

QC 20151113

Available from: 2015-11-13 Created: 2015-10-26 Last updated: 2016-04-28Bibliographically approved
2. The impact of extraction severity on polymeric hemicelluloses isolated from rapeseed straw
Open this publication in new window or tab >>The impact of extraction severity on polymeric hemicelluloses isolated from rapeseed straw
(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-185843 (URN)
Funder
Swedish Research Council Formas
Note

QC 20160428

Available from: 2016-04-28 Created: 2016-04-28 Last updated: 2016-04-28Bibliographically approved

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