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Biopolymers and materials from rapeseed straw biorefining
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
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 [en]
Rapeseed/canola straw, biorefinery, hemicelluloses, lignin, cellulose, cellulose nanoparticles, films, grafting, thermoplastic, biocomposites
Keywords [sv]
rapshalm, bioraffinaderi, hemicellulosa, lignin, cellulosa, cellulosa nano partiklar, hemicellulosafilm, ympning, termoplastisk, biokompositer
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-234656ISBN: 978-91-7729-913-4 (print)OAI: oai:DiVA.org:kth-234656DiVA, id: diva2:1246419
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
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, 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.

Keywords
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 (Scopus ID)
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
2. Rapeseed straw polymeric hemicelluloses obtained by extraction methods based on severity factor
Open this publication in new window or tab >>Rapeseed straw polymeric hemicelluloses obtained by extraction methods based on severity factor
2017 (English)In: INDUSTRIAL CROPS AND PRODUCTS, ISSN 0926-6690, Vol. 95, p. 305-315Article in journal (Refereed) Published
Abstract [en]

Rapeseed straw consists of a hard epidermis that is rich in hemicellulose and lignin and a sponge-like interior that consists mainly of cellulose. The stems were subjected to water, alkali or acid as extraction medium. The effects of the extraction conditions were quantified using severity factors and by comparing the effects of different extraction pHs, temperatures and times. Extraction with alkali resulted in a higher yield, 47 g/100 g straw in, compared to water, 6 g/100 g straw in, or an acidic, 5 g/100 g straw in, extraction process. An increase in temperature improved the extraction yield; in particular, more xylan was extracted at an elevated temperature and higher alkalinity. However, at high alkalinity, increased extraction temperatures led to a reduction in the recovery of glucomannan. The highest molecular weights (similar to 35,000 g/mol) of the extracted hemicelluloses were obtained using extraction procedures with 1.5 M NaOH at 110 degrees C and autohydrolysis at 150 degrees C. While these two parameter settings had very similar severity factors, extraction under basic conditions afforded an extract rich in xylan and low in lignin content, whereas autohydrolysis generated a glucomannan-rich extract.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Rapeseed/canola straw, Extraction, Autohydrolysis, Severity factor, Hemicellulose
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-200198 (URN)10.1016/j.indcrop.2016.10.038 (DOI)000390621600035 ()2-s2.0-85004143297 (Scopus ID)
Note

QC 20170202

Available from: 2017-02-02 Created: 2017-01-23 Last updated: 2018-09-07Bibliographically approved
3. Modified and thermoplastic rapeseed straw xylan: A renewable additive in PCL biocomposites
Open this publication in new window or tab >>Modified and thermoplastic rapeseed straw xylan: A renewable additive in PCL biocomposites
2018 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 119, p. 73-82Article in journal (Refereed) Published
Abstract [en]

Xylan extracted from rapeseed straw was chemically modified to gain hydrophobic and thermoplastic properties via macroinitiator formation followed by a free radical grafting-from polymerization with octadecyl acrylate. Biocomposites were then prepared by incorporation of 5 or 20% (w/w) rapeseed straw xylan into a poly(epsilon-caprolactone) (PCL) matrix by melt extrusion. The grafted xylan was homogeneously distributed within the biocomposite and reinforced the PCL matrix while at the same time preserving the ability to elongate to tensile strains > 500%. Analogous biocomposites made from unmodified xylan in a PCL matrix resulted in heterogeneous mixtures and brittle tensile properties.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Biocomposite, Grafting, Hemicellulose, Rapeseed/canola straw, Thermoplastic, Xylan
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-227505 (URN)10.1016/j.indcrop.2018.03.067 (DOI)000432763800009 ()2-s2.0-85045072624 (Scopus ID)
Funder
Swedish Research Council Formas, 2013-844
Note

QC 20180518

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-09-07Bibliographically approved
4. Corrigendum to “Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation” [Carbohydrate Polymers 133 (2015) 179–186](S0144861715006529)(10.1016/j.carbpol.2015.07.023)
Open this publication in new window or tab >>Corrigendum to “Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation” [Carbohydrate Polymers 133 (2015) 179–186](S0144861715006529)(10.1016/j.carbpol.2015.07.023)
2017 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 174, p. 1240-Article in journal (Other academic) Published
Abstract [en]

The authors regret that the original version of this article unfortunately contained a mistake in Table 5. The correct Table 5 and associated text is given below. “The rapeseed hemicellulose films presented here had strain-at-break values of 70% (C) and 90% (H), even with no added plasticizers (Table 5).” The authors would like to apologise for any inconvenience caused.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-234655 (URN)10.1016/j.carbpol.2017.07.037 (DOI)2-s2.0-85026534602 (Scopus ID)
Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2018-12-14Bibliographically approved
5. Rapeseed straw biorefinery
Open this publication in new window or tab >>Rapeseed straw biorefinery
(English)Manuscript (preprint) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-234654 (URN)
Note

QC 20180911

Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2018-09-11Bibliographically approved

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