Cellulose is the most abundant biopolymer in the world and the main component of paper. Modern society requires electronic devices to be more flexible and environmental friendly, which makes cellulose as a good candidate for the next generation of green electronics. However, lots of researches employed “paper-like” petroleum-based polymers to fabricate electronics rather than using real cellulose paper. Cellulose, as a representative of environmental friendly materials, caught into people's attention because of its sustainable nature, ease of functionality, flexibility and tunable surface properties, etc. There are some general challenges about using cellulose for electronics, such as its non-conductivity, porosity and roughness, but these features can be taken advantages of on certain occasions. This thesis focuses on the study of cellulose-based electronic devices by chemical or physical modification of microfibrillated cellulose (MFC). Particularly, three electronic devices were fabricated, including ionic diodes, electric double layer supercapacitors, pseudocapacitors. In addition, a rational design of dye-sensitized solar cell was investigated, although it was not directly cellulose-based, it led the way to the next generation of cellulose-based solar cells. The extraordinary physical and chemical properties of MFC were successfully leveled in those devices, in addition, inspiring and effective fabrication methods were proposed and carried out to solve the major problems faced by paper-based electronics, such as conductivity, flexibility, packaging and designs.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13102号 / 論農博第2848号 / 新制||農||1051(附属図書館) / 学位論文||H29||N5034(農学部図書室) / (主査)教授 矢野 浩之, 教授 金山 公三, 教授 辻井 敬亘 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / The present study aimed to extract nanocellulose crystalline (NCC) and nanofibrillated (NCF), and recover of lignin from oil palm mesocarpfiber (also known as palm pressed fiber). Initially, the fibers were subjected to pulping acetosolv followed by bleaching with peroxide in basic medium. The crude fiber, bleached and post acetosolv were characterized physically, chemically and morphologically. To obtain the NCC a 23 factorial design was used. NCF was obtained by combinations of the number and size of steps chamber microfluidizer. The nanocelulose obtained by acid hydrolysis (NCC) and microfluidization (NCF) was characterized by X-ray diffraction (XRD), zeta potential and particle size. According to the results, the pre-treatments were efficient, removing a significant amount of amorphous components, promoting a greater exposure of the pulp. The lignin rich fraction, called black liquor, had a yield of 62 % compared to the lignin initially present. Nanocellulose suspensions obtained showed typical gelatinous appearance and zeta potential of -26.6 mV and -40.6 mV, which configures stability.The crystallinity index of cellulose polymorphs I and II for nanocelulose crystal obtained by pre-treatment 1 was 65%, and for the other nanofibrilada nanocrystals obtained from the pre-treatment 2 were crystallinity of 70 and 61%, respectively. The nanostructures obtained still showed good thermal stability, demonstrating a greater microfibrillated nanocelulose to 267 Â C to 250 Â C the crystal. Furthermore, nanostructures were observed with typical cellulose lengths (L) between 172-404 nm and a diameter (D) lying between 5 and 12 nm, which reproduces aspect ratios (L / D) as high as 39. This demonstrates that the nanocelulose produced can be displayed as reinforcement in polymer matrices, among other applications. / O presente trabalho teve por objetivo extrair nanocelulose, cristalina (NCC) e microfibrilada (NCF), e recuperar lignina de fibras da prensagem do mesocarpo do dendÃ. Inicialmente, as fibras foram submetidas adois tipos de prÃ-tratamentos (1. mercerizaÃÃo seguida de branqueamento e 2. polpaÃÃo acetosolv seguida de branqueamento). As fibras brutas, pÃs acetosolv e branqueadas foram caracterizadas fÃsica, quÃmica e morfologicamente. Para obtenÃÃo da NCC, foi utilizado um planejamento fatorial 23, enquanto a NCF foi obtida por meio de combinaÃÃes de nÃmero de passos e tamanho de cÃmara do microfluidizador de alta pressÃo. As nanoceluloses obtidas por hidrÃlise Ãcida (NCC) e por microfluidizaÃÃo (NCF) foram caracterizadas por difraÃÃo de raio X (DRX), potencial zeta e anÃlise termogravimÃtrica (TGA). De acordo com os resultados, os prÃ-tratamentos foram eficientes, removendo quantidade significativa de componentes amorfos, promovendo uma maior exposiÃÃo da celulose e um consequente aumento do Ãndice de cristalinidade. A fraÃÃo rica em lignina, denominada licor negro, apresentou rendimento de 62% em relaÃÃo ao conteÃdo de lignina inicialmente presente. As suspensÃes de nanocelulose obtidas apresentaram aspecto gelatinoso tÃpico e potencial zeta variando de -26,6 mV a -40,6 mV, o que configura estabilidade. Os Ãndices de cristalinidade dos polimorfos de celulose I e II, para nanocelulose cristalina obtida atravÃs do prÃ-tratamento 1 foi de 65%, quanto aos outros nanocristais e nanofibrilada obtidas do prÃ-tratamento 2 apresentaram cristalinidade de 70 e 61%, respectivamente. As nanoestruturas obtidas apresentaram ainda boa estabilidade tÃrmica, demostrando-se maior para a nanocelulose microfibrilada, 267 ÂC contra 250ÂC para as cristalinas. Foram observadas, ainda, nanoestruturas de celulose tÃpicas com comprimentos (L) entre 172 nm a 404 nm e diÃmetros (D) situados entre de 5 nm e 12 nm, o que reproduziu razÃes de aspecto (L/D) tÃo altas quanto 39. Isso demonstra que as nanocelulose produzidas podem ser indicadas como reforÃo em matrizes polimÃricas, dentre outras aplicaÃÃes.

Papers are coated in order to improve the properties of the surface, to improve printability and to include new functionalities like barriers properties. Typical coating formulation contains a high number of components, some are made from minerals and others are manufactured from petroleum. The barrier properties of today's paper based packages are plastics and/or aluminum             foil. Environmentally friendly substitutie of these nonrenewable materials are needed.  Nanocellulose is a promising material                 and of a growing interest as an alternative to petroleum-based materials, since nanocellulose films/coatings have been shown to have excellent mechanical and barrier properties.   This project aimed to evaluate nanocellulose in combination with minerals in paper coatings. The project had two approaches. One was to evaluate the barrier properties of MFC coatings with mineral included. The second part was about coatings for           printing matters, and evaluation of the possibility to replace petroleum-based binders in the coating color with MFC. Barrier properties were evaluated by measuring the air permeability of the coatings. The properties of the coating affecting the         printability in offset printing examined was the surface energy, the gloss, the roughness of the coatings, the strength and the offset ink setting.   Carboxymethylated nanocellulose formed denser films and had superior barrier properties compared with enzymatically pretreated nanocellulose. Adding of minerals did not affect the barrier properties of the MFC coatings to a significant extent.         Therefore, minerals cannot be added to enhance the barrier but it can be added to reduce the cost of the coating process without losing any barrier properties.                                 The print quality depends on how the ink interacts with the coating. These coatings did have a relatively high surface energy, which is preferable for printing with waterborne ink. It was also shown that the absorption abilities increased when the amount of MFC was increased. However, offset printing demands high surface strength and addition of MFC in the coating color                     drastically decreased the strength. This means that the coatings produced in this work are not strong enough and thereby not           suitable for offset printing. However other printing technologies put lower demand on surface strength and are still possible.

<p>Today, the majority of materials used for single-use packaging are petroleum-based synthetic polymers. With increased concern about the environmental protection, efforts have been made to develop alternative biodegradable materials from renewable resources. Starch offers an attractive alternative since it is of low cost and abundant. However, the starch material is brittle without plasticizer and the mechanical properties of starch materials are highly sensitive to moisture.</p><p>In nature, the plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. This interesting combination of properties is attributed to a network based on cellulose microfibrils. Inspired by this, microfibrillated cellulose (MFC) reinforced starch-based nanocomposites films and foams were prepared. Films with a viscous matrix and MFC contents from 10 to 70wt% were successfully obtained by solvent casting. The films were characterized by DSC, DMA, FE-SEM, XRD, mercury density measurements, and dynamic water vapor sorption (DVS). At 70wt% MFC content a high tensile strength together with high modulus and high work of fracture was observed. This was due to the nanofiber and matrix properties, favourable nanofiber-matrix interaction, a good dispersion of nanofibers and the MFC network.</p><p>Novel nanocomposite foams were obtained by freeze-drying aquagels prepared from 8wt% solutions of amylopectin starch and MFC. The MFC content was varied from 10 to 70wt%. For composite foam with MFC contents up to 40wt%, improved mechanical properties were observed in compression. The mechanical properties depended both on the cell wall properties and the cell-structure of the foam. The effect of moisture (20-80% RH) on the dynamical properties of composite foam with 40wt% MFC was also investigated and compared to those of neat starch foam. Improved storage modulus was noted with MFC content, which was a result of the nanofiber network in the cell-wall. In addition, the moisture content decreased with MFC content, due to the less hydrophilic nature of MFC.</p>

Ce travail se situe dans un contexte de développement de matériaux barrières pour l'emballage alimentaire papier-carton utilisant des microfibrilles de cellulose (MFC), ce qui donne une dimension renouvelable, recyclable, et biodégradable. Pour cela, deux stratégies ont été étudiées : l'utilisation des MFC pour la formation d'une couche barrière laminée à l'état humide sur carton, et en tant qu'additif dans une sauce de couchage barrière base aqueuse. Il a été montré que l'utilisation des MFC pour la production de couches barrières est prometteuse dans les deux cas. La lamination de MFC sur carton a permis d'obtenir de bonnes propriétés barrières à l'oxygène et à la graisse en utilisant des MFC hautement fibrillées. L'association carton-MFC a présenté une forte adhésion après séchage, permettant d'éviter l'utilisation de colle. Dans le cas du couchage composite, en vue de diminuer la viscosité et améliorer la barrière, il a été trouvé préférable d'utiliser un faible taux de MFC dans un alcool polyvinylique (PVOH) complètement hydrolysé ayant un faible degré de polymérisation. L'ajout de MFC dans une sauce de couchage composite a montré leur capacité à améliorer la cinétique de séchage du PVOH. L’utilisation combinée de MFC et de charges lamellaires a présenté un effet de synergie sur leurs états de dispersions dans une solution de PVOH, permettant leur utilisation pour l'amélioration de la barrière à la vapeur d'eau en conditions humides, tout en évitant la formation d'agrégats qui détérioreraient la barrière à l'oxygène. Ce travail a contribué à démontrer le potentiel des MFC pour la formation de couches barrières, ouvrant la voie au développement de nouveaux matériaux d'emballages plus responsables. / This study takes place in a context of development of paper-based barrier packaging materials, using of microfibrillated cellulose (MFC) that brings renewability, recyclability, and biodegradability. Two strategies have been investigated: the wet lamination of a MFC barrier layer on board, and the use of MFC as additive in a water-based barrier coating colour. The promising use of MFC for the formation of barrier layers has been demonstrated in both cases. The wet lamination of MFC on board led to good oxygen and grease barrier properties, using highly fibrillated MFC. The board-MFC complex presented a strong adhesion after drying, without requiring glue. In the case of barrier coating, in order to obtain a low viscosity suspensions leading to high barrier layers, the use of highly fibrillated MFC mixed with a fully-hydrolysed poly(vinyl alcohol (PVOH) of low degree of polymerisation has been preferred. The addition of MFC in PVOH demonstrated its potential for improving the drying behaviour of water-barrier barrier coating colours. The combined use of MFC and layered silicates evidenced a synergistic effect on their dispersion in a PVOH solution, leading to an improved water vapour barrier while avoiding the formation of aggregates that otherwise damage the oxygen barrier. The work contributed to demonstrate the potential of MFC to be used for the formation of barrier layers, paving the way for the development of more sustainable barrier packaging materials.

Développement de nouveaux matériaux d'emballage à base de micro- et nano-fibrilles de cellulose. Les micro- et nano-fibrilles de cellulose (MFC/NFC) sont des nanomatériaux issus de ressources renouvelables présentant un fort intérêt notamment pour le domaine de l'emballage. En plus des avantages naturels de la cellulose, ces matériaux offrent des propriétés barrières prometteuses (Oxygen, graisse), de bonnes propriétés de résistance mécanique ainsi que la possibilité de produire des films transparents. L'objectif de cette thèse était de développer par des procédés d'endution un carton barrière au gaz et aux graisses en utilisant les MFC/NFC. Différentes suspensions de MFC/NFC ont été premièrement characterisées puis utilisées pour la production de films afin de déterminer leurs propriétés intrinsèques. Des films modèles ont ensuite été développés avec la production de composites matrice/MFC. Une dernière partie était focalisée sur l'introduction de MFC/NFC dans des sauces de couchage afin de développer une couche barrière à la surface d'un carton. Un démonstrateur a ainsi été validé à l'échelle pilote. Le potentiel des MFC/NFC a été démontré comme agent de séchage et comme composant principale d'une couche barrière. Mots clès: Micro- et nano-fibrilles de cellulose, couche barrières, procédés d'enduction / Development of new packaging materials based on micro- and nano-fibrillated cellulose. The micro- and nanofibrillated cellulose (MFC/NFC) are nanomaterials from revewable resource with a high interest and partly for the packaging development. MFC combined both interesting properties (high tensile strength, good barrier to oxygen and grease, good transparency) and the advantages of natural cellulose source. The objective of this thesis was to develop a barrier packaging board based on MFC/NFC by coating processes. Firstly, the study focussed on the characterisation of the MFC suspensions, on the manufacturing of MFC self-standing films and on the determination of their properties. Secondly, the development of MFC based composites was studied as model films. The last part was devoted to the introduction of MFC in coating colours in order to develop a barrier layer at the board surface. Trials at pilot scale demonstrated the industrial feasibility of this product. The potential of the use of MFC/NFC was demonstrated to be used as a drying additive and a main composant of barrier layer. Keywords: Micro- and nanofibrillated cellulose, barrier layer, coating processes

Genom laborativa försök skulle avvattning och retention av nanocellulosa i en DDA (Dynamic drainage analyzer) undersökas. Detta genom att tillsätta retentionskemikalier i varierande mängder för att se hur det påverkade avvattningen. Uppdragsgivaren var Innventia och laborationerna utfördes på SP:s laboratorium där DDA instrument fanns tillgängligt. DDA instrumentet liknar den maskin som används för papperstillverkning och därför anses det vara möjligt att kunna avvattna nanocellulosa på liknande instrument. Målet med examensarbetet var att få fram en nanocellulosafilm med goda barriärsegenskaper men också se hur tillsats av bärarfibrer påverkar filmens egenskaper. Målet var också att se om retention och avvattningstiden för nanocellulosa hänger ihop och om det går att få fram repeterbara resultat. Två olika viror undersöktes också i de laborativa experimenten i DDA, en som benämns som Albanyviran och en som benämns som Stratexviran. Albanyviran är tätare än Stratexviran och effekten av viratäthet på retention och avvattningstid undersöktes. Nanocellulosa eller Mikrofibrillär cellulosa (MFC) är ett nytt och förnybart material som utvinns ur träfibrer och karakteriseras av sitt geléaktiga utseende[4]. Nanocellulosan lämpar sig utmärkt för en mängd olika produkter t.ex. som barriär, enskilt i form av filmer eller i blandade produkter. Vid tillverkning av nanocellulosa används en homogenisator som sönderdelar cellulosafibrer till fibriller och fibrillaggregat. Detta var tidigare ett problem då fibrerna satte igen homogenisatorn och tillverkningen var mycket energikrävande[4]. När det gäller filmtillverkning av nanocellulosa kvarstår problemet när det kommer till avvattningen. Nanocellulosan späddes till önskad koncentration och innan de laborativa försöken kördes den genom en homogenisator för att dispergera fibrillerna i vätskan efter spädningen. Bärarfibrerna slogs upp i en uppslagare med två liter kranvatten för att sedan tillsättas till den homogeniserade nanocellulosan. Under försöket i DDA varierades mängden och andelen MFC (mikrofibrillär cellulosa) och bärarfibrer (Modorefmassa). Till MFC och bärarfibersuspensionen i DDA:n tillsattes sedan två retentionskemikalier vid varje försök, C-PAM PL-1520 och EKA NP-780 i varierande mängder. Efter avvattningen i DDA:n pressades filmen vid olika tryck och tider för att därefter mäta filmernas ytvikt och syrgasbarriär. Den film som ansågs mest lämplig gällande avvattning i DDA under försöken var vid 0,2 % med 90 % MFC och 10 % bärarfibrer. Filmen gav den högsta retentionen, en god syrgasbarriär och var lätt att hantera. Det som kan ses från resultaten av syrgasbarriären är att vid 0,2 % med 90 % MFC och 10 % bärarfibrer erhölls det lägsta OTR (oxygen transmission rate) -värdet på 0,53 vilket visar på en bra syrgasbarriär. Retentionen för det försöket var det högsta på 87,1 % medan avvattningstiden låg på närmare 250 sekunder. Avvattningstiderna var höga, dock så var det vid denna totalkoncentration ibland svårt att se när avvattningen avslutades då tiden klockades manuellt. Det som kan ses utifrån resultaten är att bärarfibrerna inte påverkar filmerna negativt utan kan gynna både så retentionen och syrgasbarriären blir bättre, dock fås en högre ytvikt och avvattningstiderna blir längre. / Through laboratory experiments, dewatering and retention of nanocellulose in a DDA (Dynamic Drainage Analyzer) were analysed. By adding retention chemicals in varied amounts, the effects on the dewatering was shown. The Job initiator was Innventia and the laboratory work were made at SP's laboratory where the DDA instrument was available. The DDA instrument is similar to the machine that is used for paper manufacturing in a large scale and therefore, it could be possible to dewater nanocellulose on a similar instrument. The goal of the thesis was to develop a nanocellulose film with good barrier properties but also to see how adding carrier fibers effect the properties of the film. The goal was also to see if the retention and dewatering time of nanocellulose are connected and whether it is possible to obtain repeatable results. Two different wires were also examined in the laboratory experiments in a DDA, the Albanywire and the Stratexwire. The Albany wire was denser than the Stratex wire and the effect that the density caused on retention and dewatering time was examined. Nanocellulose or Microfibrillated cellulose (MFC) is a new and renewable material that is made from wood fibers and is characterized by its gelatinous appearance. [4] Nanocellulose is suited for a variety of products, such as barriers, alone in the form of films or mixed in products. In the manufacture of nanocellulose a homogenizer is used which decomposes cellulose fibers to fibrils fibril aggregate. This was previously a problem while the fibers clogged the homogenizer and the production had a high energy consumption. [4] When it comes to making a nanocellulose film the problems with dewatering remains. The nanocellulose was diluted to the desired concentration and before the laboratory experiments it was run through a homogenizer, to disperse the fibrils in the liquid after the dilution. The carrier fibers was prepared in a blender with two liters of tap water before it was added to the homogenized nanocellulose. During the experiment in the DDA the amount and proportion of the MFC (microfibrillar cellulose) and carrier fibers (Modorefmassa) was varied. To the MFC and carrier fiber suspension in the DDA two retention chemicals were added in each experiment, C- PAM PL -1520 and EKA NP- 780 in varying amounts. After the dewatering of nanocellulose in the DDA the films were pressed at different pressures and times, thereafter the oxygen permeability was analyzed. The film that was considered the most suitable referring to dewatering in the DDA during the attempts was at 0.2 % with 90 % MFC and 10 % carrier fibers. The film gave the highest retention, a good oxygen barrier and was easy to handle. What can be seen from the results of the oxygen barrier measurement is that at 0.2 % with 90 % MFC and 10% carrier fibers obtained the lowest value OTR (oxygen transmission rate), which indicates on a good oxygen barrier. Retention at this concentration was the highest at 87.1 %, while the drainage time was nearly 250 seconds. The dewatering time was high, however during this concentration it’s sometimes difficult to see when the dewatering ended while the time was clocked manually. Conclusions from the results are that the carrier fibers doesn’t have a negatively effect on the films, rather they can benefit both the retention and oxygen barrier, however a higher paper weight was obtained and the dewatering time became longer.

Today, the majority of materials used for single-use packaging are petroleum-based synthetic polymers. With increased concern about the environmental protection, efforts have been made to develop alternative biodegradable materials from renewable resources. Starch offers an attractive alternative since it is of low cost and abundant. However, the starch material is brittle without plasticizer and the mechanical properties of starch materials are highly sensitive to moisture. In nature, the plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. This interesting combination of properties is attributed to a network based on cellulose microfibrils. Inspired by this, microfibrillated cellulose (MFC) reinforced starch-based nanocomposites films and foams were prepared. Films with a viscous matrix and MFC contents from 10 to 70wt% were successfully obtained by solvent casting. The films were characterized by DSC, DMA, FE-SEM, XRD, mercury density measurements, and dynamic water vapor sorption (DVS). At 70wt% MFC content a high tensile strength together with high modulus and high work of fracture was observed. This was due to the nanofiber and matrix properties, favourable nanofiber-matrix interaction, a good dispersion of nanofibers and the MFC network. Novel nanocomposite foams were obtained by freeze-drying aquagels prepared from 8wt% solutions of amylopectin starch and MFC. The MFC content was varied from 10 to 70wt%. For composite foam with MFC contents up to 40wt%, improved mechanical properties were observed in compression. The mechanical properties depended both on the cell wall properties and the cell-structure of the foam. The effect of moisture (20-80% RH) on the dynamical properties of composite foam with 40wt% MFC was also investigated and compared to those of neat starch foam. Improved storage modulus was noted with MFC content, which was a result of the nanofiber network in the cell-wall. In addition, the moisture content decreased with MFC content, due to the less hydrophilic nature of MFC. / QC 20101118

The context of this thesis is a research project focused on the investigation of a renewable biopolymer-poly(lactic acid) (PLA) as a potential replacement of petroleum-based polymers in advanced nanocomposites reinforced with Microfibrillated cellulose (MFC). MFC is extracted from wood, which is a renewable, sustainable, carbon neutral and recyclable material. This advanced MFC-PLA bio- based composite material is expected to allow for the substitution of petroleum-based plastics in various markets and applications. The specific objectives of the thesis are: 1) to describe the morphological characterization of MFC used for prototype MFC-PLA composites, and 2) to determine the mechanical properties of the prototype MFC-PLA nanocomposites formulation generated in form of thin transparent films. In order to meet this objective it was necessary to: 2.1) develop a methodology for optical strain measurement in transparent thin films; and 2.2) develop an effective methodology for obtaining multiple mechanical properties from small number of specimens of prototype materials subjected to tensile tests. Two types of MFC, one obtained by courtesy of University of Maine and the other purchased from Innventia AB company, were investigated under a field emission scanning electron microscopy (FESEM). The micrographs obtained from FESEM showed that both types of MFC were of complex hierarchical structures, which did not allow qualitative characterization of the morphological features in terms of particulate composites nor cellular solids. Since prototype formulations of MFC-PLA composites were generated in small amounts (typically one Petri dish) in a form of thin transparent films, there was a need for quick and efficient assessment of their key mechanical properties that would provide feedback and guide further prototyping work. An optical measurement method based on digital image correlation (DIC) principle was developed to measure the deformation and strains of the tensile film samples. In our study, the accuracy and precision of the measurement of deformation were ±1.5 µm and 0.4 µm respectively. The corresponding accuracy and precision in terms of strains were ±30 µstrain and 75 µstrain respectively. This method can be successfully used to determine the critical mechanical properties, such as elastic modulus, toughness and Poisson's ratio, of transparent thin films by a single tensile test, all of which require precise strain measurement. In addition, this optical measurement method makes it possible to significantly simplify the testing for measuring essential work of fracture (EWF), an important material property of thin transparent films. In traditional method, measurement of EWF requires large amount of notched specimens. However, our study showed that only a small amount of notched specimens were needed to measure the EWF of a material. This method could not be successfully used to determine EWF from un-notched tensile specimens. / Graduation date: 2012 / Folder labeled "UMaine MFC aerogel" contains SEM micrographs of MFC from University of Maine (referred as type A MFC in the thesis). Two pieces of leaf-like flakes at different locations were cut by Focused Ion Beam (FIB) in order to observe the internal structure of the flakes. Folder "FIB_01 ": a series of SEM micrographs of FIB-cut flake at different magnification levels. Folder "FIB_02 ": another series of SEM micrographs of FIB-cut flake at various magnification levels. Folder labeled "Swedish MFC aerogel" contains SEM micrographs of MFC from Innventia AB company, Sweden (referred as type B MFC in the thesis). There is a series of SEM micrographs of type B MFC aerogel at various magnification levels in this folder.