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Eco-Friendly Cellulose Nanofibrils Designed by Nature: Effects from Preserving Native State
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0002-1336-5119
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.ORCID iD: 0000-0001-5818-2378
(English)Manuscript (preprint) (Other academic)
National Category
Materials Engineering Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-262841OAI: oai:DiVA.org:kth-262841DiVA, id: diva2:1362799
Note

QC 20191023

Available from: 2019-10-21 Created: 2019-10-21 Last updated: 2019-10-23Bibliographically approved
In thesis
1. Eco-friendly Holocellulose Materials for Mechanical Performance and Optical Transmittance
Open this publication in new window or tab >>Eco-friendly Holocellulose Materials for Mechanical Performance and Optical Transmittance
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cellulosic materials can be sustainable replacements for fossil-based plastics; yet for some applications improvements are needed for mechanical properties, optical transmittance and eco-friendly characteristics. In this thesis, holocellulose materials are investigated for this purpose, and processing-structure-property relationships are discussed. Molded fibers, without added polymer binder, is of particular interest for semi-structural applications, where facile recycling is possible with highly preserved fiber properties.

Mild delignification is carried out to obtain ramie fibers, spruce holocellulose fibers and holocellulose nanofibrils. The chemical composition, molar mass, crystallinity, fiber length/width, and single fiber strength are measured. Fibers and fibrils show well-preserved native structure. Using water-based hot-pressing, fibers and fibrils are processed into different fiber network materials, including paper structures of 50% porosity, high density molded fibers, and high density nanopaper films. Biocomposites are obtained through methyl methacrylate impregnation and polymerization with molded fibers as reinforcing networks. Fiber orientation is quantified using 2D X-ray diffraction, mechanical properties are determined by tensile testing, and optical properties are measured by transmittance/haze tests in an integrating sphere. Holocellulose materials show much superior mechanical properties and optical transmittance to comparable materials based on industrially available kraft fiber grades. Strong effects from micro-, nano- and molecular scale structures are observed and discussed.

The colloidal stability, redispersibility, and surface modification of holocellulose nanofibrils, as well as recycling and 3D-shaping performance of paper-like structures are investigated. Eco-friendly characteristics include high fiber yield, reduced need for chemical modification and excellent recycling performance with reduced embodied energy in the final material. The enhanced performance of holocellulose materials, compared with materials from kraft fibers, are related to the effects of well-preserved cellulose and hemicellulose structures, as well as structural homogeneity at both molecular, nanofibril and fiber length scales.

Abstract [sv]

Cellulosa-baserade material från förnyelsebar råvara kan fungera som ersättning för fossilbaserade plaster. Den utvecklingen skulle underlättas av förbättrade mekaniska egenskaper, optisk transparens och förbättrad miljövänlig profil (återvinning, koldioxidutsläpp, energiåtgång). Material från holocellulosa analyseras, och relationer mellan process, struktur och egenskaper diskuteras.

Mild delignifiering används för att framställa ramie-fibrer, holocellulosa-fibrer från gran och nanofibriller från holocellulosa. Kemisk sammansättning, molekylvikt, kristallinitet, fiberlängd och diameter, och hållfasthet hos enskilda fibrer studeras. Med hjälp av formpressning, framställs olika typer av material baserade på fibernätverk. Det innefattar pappers-strukturer med 50% porositet, formpressade fibrer, och nanopapper. Biokompositer framställs genom impregnering med metylmetakrylat och polymerisering i närvaro av ett förstärkande nätverk av holocellulosa-fibrer.

Fiberorientering kvantifieras med 2D röntgenspridning, mekaniska egenskaper mäts genom enaxliga dragprov och optiska egenskaper mäts genom att använda en integrerande sfär. Material från holocellulosa har mycket bättre egenskaper än motsvarande material baserade på blekta fibrer från kraft-processen. Starka effekter från struktur på molekylär, nano och mikroskala diskuteras och analyseras i arbetet.

För nanofibriller från holocellulosa undersöks kolloidal stabilitet, återdispergering, ytmodifiering och dessutom återvinning och tredimensionell formning av pappersliknande strukturer. Miljövänliga attribut inkluderar högt fiberutbyte, minskat behov av kemisk modifiering och mycket goda återvinnings-prestanda. Förbättrad prestanda hos holocellulosa-material jämfört med kraft-fibrer, beror på effekter från välbevarad cellulosa, och hemicellulosa, liksom strukturell homogenitet på molekylär, nano och fiberskala.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. p. 73
Series
TRITA-CBH-FOU ; 2019:60
National Category
Paper, Pulp and Fiber Technology Materials Engineering Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-262895 (URN)978-91-7873-351-4 (ISBN)
Public defence
2019-11-19, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 2019-10-23

Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2019-10-23Bibliographically approved

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Yang, XuanReid, Michael S.Olsén, PeterBerglund, Lars

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