It is in the nature of the human species to find solutions of complex technical problems and always strive for improvements. The development of new materials is not an exception. One of the many man-made materials is carbon fibre (CF). Its excellent mechanical properties and low density have made it attractive as the reinforcing agent in lightweight composites. However, the high price of CF originating from expensive production is currently limiting CF from wider utilisation, e.g. in the automotive sector.   The dominating raw material used in CF production is petroleum-based polyacrylonitrile (PAN). The usage of fossil-based precursors and the high price of CF explain the strong driving force of finding cheaper and renewable alternatives. Lignin and cellulose are renewable macromolecules available in high quantities. The high carbon content of lignin is an excellent property, while its structural heterogeneity yields in CF with poor mechanical properties. In contrast, cellulose has a beneficial molecular orientation, while its low carbon content gives a low processing yield and thus elevates processing costs.   This work shows that several challenges associated with CF processing of each macromolecule can be mastered by co-processing. Dry-jet wet spun precursor fibres (PFs) made of blends of softwood kraft lignin and kraft pulps were converted into CF. The corresponding CFs demonstrated significant improvement in processing yield with negligible loss in mechanical properties relative to cellulose-derived CFs. Unfractionated softwood kraft lignin and paper grade kraft pulp performed as good as more expensive retentate lignins and dissolving grade kraft pulp, which is beneficial from an economic point of view.   The stabilisation stage is considered the most time-consuming step in CF manufacturing. Here it was shown that the PFs could be oxidatively stabilised in less than 2 h or instantly carbonised without any fibre fusion, suggesting a time-efficient processing route. It was demonstrated that PF impregnation with ammonium dihydrogen phosphate significantly improves the yield but at the expense of mechanical properties.   A reduction in fibre diameter was beneficial for the mechanical properties of the CFs made from unfractionated softwood kraft lignin and paper grade kraft pulp. Short oxidative stabilisation (&lt;2 h) of thin PFs ultimately provided CFs with tensile modulus and strength of 76 GPa and 1070 MPa, respectively. Considering the high yield (39 wt%), short stabilisation time and promising mechanical properties, the concept of preparing CF from lignin:cellulose blends is a very promising route. / Det ligger i människans natur att hitta lösningar på komplexa tekniska problem, samt att alltid sträva efter förbättringar. Utvecklingen av nya material är inget undantag. Ett av flera material utvecklade av människan är kolfiber. Dess utmärkta mekaniska egenskaper samt låga densitet har gjort det attraktivt som förstärkningsmaterial i lättviktskompositer. Det höga priset på kolfiber, vilket härstammar ur en kostsam framställningsprocess, har förhindrat en mer utbredd användning i exempelvis bilindustrin.   Det dominerande råmaterialet för kolfiberframställning är petroleumbaserad polyacrylonitril (PAN). Användandet av fossila råvaror och det höga priset på kolfiber förklarar den starka drivkraften att hitta billigare och förnyelsebara alternativ. Lignin och cellulosa är förnyelsebara makromolekyler som finns tillgängliga i stora kvantiteter. Det höga kolinnehållet i lignin gör det mycket attraktivt som råvara för kolfiberframställning, men dess heterogena struktur ger en kolfiber med otillräckliga mekaniska egenskaper. Däremot har cellulosa en molekylär orientering som är önskvärd vid framställning av kolfiber, men dess låga kolinehåll ger ett lågt processutbyte som i sin tur bidrar till höga produktionskostnader.             Det här arbetet visar att många av de problem som uppstår med kolfiber från respektive råvara kan kringgås genom att utgå från blandningar av desamma. Prekursorfibrer från blandningar av kraftlignin och kraftmassa från barrved tillverkade med luftgapsspinning konverterades till kolfiber. Utbytet för kolfibrerna som framställdes var mycket högre än vid framställning från endast cellulosa. Ofraktionerat barrvedslignin och kraftmassa av papperskvalitet presterade lika bra som de dyrare retentatligninen och dissolvingmassan, vilket är fördelaktigt ur ett ekonomiskt perspektiv.   Stabilisering är det mest tidskrävande processteget i kolfibertillverkning. I det här arbetet visades det att prekursorfibrerna kunde stabiliseras på kortare än två timmar, eller direktkarboniseras utan någon sammansmältning av fibrerna. Detta indikerar att en tidseffektiv produktion kan vara möjligt. Impregnering av prekursorfibrerna med ammoniumdivätefosfat ökade utbytet avsevärt, men med lägre mekaniska egenskaper som bieffekt.           Kolfibrernas mekaniska egenskaper ökade vid en diameterreduktion. En kort oxidativ stabilisering under två timmar i kombination med tunna prekursorfibrer gav kolfiber med en elasticitetsmodul på 76 GPa och dragstyrka på 1070 MPa. Att göra kolfiber från blandningar av lignin och cellulosa är ett lovande koncept om det höga utbytet (39%), den korta stabiliseringstiden samt de lovande mekaniska egenskaperna tas i beaktande. / <p>QC 20190226</p>

The aim of this thesis is to explore how theoretical studies on handicrafts may be rewarding and usefull for a craftsman. The aim is also to explore how quality is defined within crafts and to explore different aesthetic qualities that can be achieved within the craft of cabinetmaking. In addition, the aim is also to broaden the view on how skillfullnes may be expressed within the craft of cabinetmaking. The work begins with theoretical studies of two craft philosophers - David Pye and Soetsu Yanagi. Then, their ideas are applied practically through the making of two pieces of furniture. Aesthetic expressions characterized by randomness, imperfection and irregularity is specially sought after. The conclusions of the thesis shows that theoretical studies may be benefiting and rewarding for a craftsman. / Syftet med detta arbete är att visa hur teoretiska studier om hantverk är utvecklande och användbara för en praktiserande hantverkare. Syftet är också att undersöka vad som definierar gott hantverk samt att undersöka vilka olika estetiska kvalitéer som kan åstadkommas inom snickerihantverket. Dessutom vill arbetet bredda synen på hur skicklighet och förståelse för materialet trä kan uttryckas. Arbetet inleds med teoretiska studier av två hantverksfilosofer - David Pye och Soetsu Yanagi. Därefter tillämpas deras idéer praktiskt genom tillverkningen av två möbler. Särskilt fokus läggs på att åstadkomma estetiska uttryck som präglas av slump, imperfektion och irregularitet. Slutsatserna visar att ett teoretiska studier kan bredda en praktiserande hantverkares syn på vad som är möjligt att åstadkomma inom snickerihantverket samt att materialet trä tillåter en bredd av uttryck.

La biomasse lignocellulosique comprend les sous-produits agricoles et industriels pouvant être utilisés comme matière première dans des bioprocédés variés destinés à produire des molécules d'intérêt énergétique ou chimique. Ces ressources lignocellulosiques, peuvent notamment être fournies par l'industrie papetière qui est particulièrement adaptée pour les bio-raffineries modernes car elle est en capacité de produire en grande quantité un substrat ayant une faible teneur en lignine et sans composés inhibiteurs. La bagasse de canne à sucre est également un substrat prometteur par sa composition chimique simple et son abondance dans les pays tropicaux. Lors de l'utilisation de ces substrats, l'hydrolyse enzymatique constitue une étape cruciale permettant la transformation des fibres de cellulose en une source de carbone fermentescible. Si les aspects biochimiques de cette étape d'hydrolyse font l'objet de nombreuses recherches et de développements, les réactions sous haute teneur en matière sèche font apparaître des limitations physiques qui sont beaucoup moins étudiées et analysées mais constituent des verrous scientifiques et technologiques qui freinent actuellement l'utilisation de cette ressource abondante et durable. Ce travail s'inscrit dans ce contexte et propose l'étude de cette étape d'hydrolyse enzymatique de la lignocellulose en s'intéressant conjointement aux aspects biochimiques et physiques de façon à aller vers une compréhension et une maîtrise des transferts (de masse, de chaleur) dans les réactions à forte concentration en substrat. La stratégie adoptée a consisté à réaliser et analyser des réactions d'hydrolyse sous différentes conditions opératoires en travaillant dans un premier temps sur des concentrations intermédiaires (suspension semi-diluée), c'est-à-dire en introduisant, mais de façon limitée, les complexités dues aux interactions entre particules/fibres de lignocellulose. Les résultats obtenus sont ensuite utilisés pour élaborer une stratégie adaptée aux fortes concentrations. Les aspects physiques analysés sont essentiellement le comportement rhéologique du milieu réactionnel ainsi que la morpho-granulométrie des objets en suspension. Différentes métrologies, tant in-situ que ex-situ, ont été mises en œuvre et apportent des résultats complémentaires. Les études ont été menées sur un substrat de référence, le papier Whatman, et deux substrats à vocation industrielle: la pâte à papier et la bagasse de canne à sucre. La stratégie d'étude porte sur les aspects suivants: (i) le suivi de l'évolution des comportements rhéologiques et des propriétés morphologiques des suspensions au cours de l'hydrolyse, (ii) l'étude des mécanismes d'hydrolyse lors de la dégradation des substrats, (iii) l'étude de l'impact de la composition et de la structure des substrats sur les cinétiques de solubilisation et d'hydrolyse, (iv) la quantification de la contribution des différentes activités enzymatiques, seules ou en mélange par une approche physique multi-échelle et (v) le contrôle et l'optimisation des conditions d'alimentation dans un procédé discontinu alimenté (fed-batch) afin d'atteindre des conditions de milieu concentré. Les chapitres 1 et 2 de ce document sont consacrés à une étude bibliographique du sujet et à la présentation des matériels et méthodes mis en œuvre. Le troisième chapitre présente les résultats obtenus et leur analyse. Il est constitué de trois sections: tout d'abord une étude des propriétés des différents enzymes ou cocktail d'enzymes utilisés, des substrats retenus et des suspensions avec, notamment, la détermination des régimes semi-dilués et concentrés. Ensuite sont présentées et analysées les hydrolyses effectuées en milieu semi-dilué. Les mécanismes d'hydrolyse (fragmentation, solubilisation, hydratation et séparation des agglomérats) sont étudiés pour diverses concentrations et divers enzymes/cocktails. Enfin les résultats en milieu concentré sont présentés dans une dernière section. / Lignocellulosic biomass consists of several agriculture and industrial by-products that can be used as raw material for several bioprocesses to obtain range of products. Among lignocellulosic sources, the pulp & paper industry is appropriated for modern bio-refining thank to pulp with low lignin content and free of inhibitory compounds. Besides, sugarcane bagasse is a very promising feedstock because of its simple chemical composition and its abundancy especially in tropical countries. In the bioconversion of lignocellulose, enzymatic hydrolysis is a crucial step that allows the transformation of cellulosic and hemicellulosic fibers into fermentable carbon sources. The lack of knowledge about physical limitations and hydrolysis mechanisms, especially at high dry matter content, stands as the main barrier which forbids the scale-up of bio-refinery processes. Thus, the efficient and sustainable use of lignocellulosic resources is currently a major challenge and need to be investigated. In this context, this PhD focused on the enzymatic hydrolysis of lignocellulose by both physical and biochemical approaches. The strategy consisted in carrying out and in analyzing the hydrolysis reactions under different operating conditions with semi-dilute suspensions. Then, obtained results were used to develop a hydrolysis strategy for concentrated suspensions. Different methodologies, in- and ex-situ analyses, were implemented and provided complementary results. From physical approach, analyses consisted in rheological behavior of suspensions as well as the morpho-granulometry of particles. The study was carried out on a reference substrate, Whatman paper, and on two industrial substrates, paper pulp and sugarcane bagasse. The strategy aimed to investigate different stakes: (i) evolution of rheological behaviors and the morphological properties of suspensions, (ii) hydrolysis mechanisms during the degradation of substrates, (iii) impact of substrate composition and structure on solubilization and hydrolysis kinetics, (iv) quantification of the contribution of single enzyme and enzyme mixture activities by multi-scale physical approaches and (v) control and optimization of feeding parameters for fed-batch process in order to access to concentrated suspension. Chapters 1 and 2 of this document are devoted to a research bibliographic and presentation of materials and methods. The third chapter presents obtained results and discussion in three sections. The first one is a study of the properties of different enzymes and substrates, in particular, the determination of semi-dilute and concentrated regime. Subsequently the enzymatic hydrolysis at semi-dilute regime is presented to highlight the hydrolysis mechanisms (fragmentation, solubilization, solvation and agglomerate separation) in relationship with enzyme mixtures and dosages. Finally, results in concentrated regime are discussed in the final section.

Food packaging should ensure the safety and quality of food, minimize spoilage and provide an easy way of storing and handling it. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. Using both experimental data and computer modelling, this thesis explains some aspects of how the structure of barrier coatings influences the mass transport of oxygen with the aim of obtaining essential knowledge that can be used to optimize the performance of barriers. Barrier coatings are produced from polyvinyl alcohol and kaolin blends that are coated onto a polymeric support. The chemical and physical structures of these barriers were characterized according to their influence on permeability in various climates. At a low concentration of kaolin, the crystallinity of polyvinyl alcohol decreased; in the thinner films, the kaolin particles were orientated in the basal plane of the barrier coating. The experimental results indicated a complex interplay between the polymer and the filler with respect to permeability. A computer model for permeability incorporating theories for the filled polymeric layer to include the polymer crystallinity, addition of filler, filler aspect ratio and surrounding moisture was developed. The model shows that mass transport was affected by the aspect ratio of the clay in combination with the clay concentration, as well as the polymer crystallinity. The combined model agreed with the experiments, showing that it is possible to combine different theories into one model that can be used to predict the mass transport. Four barrier coatings: polyethylene, ethylene vinyl alcohol + kaolin, latex + kaolin and starch were evaluated using the parameters of greenhouse gas emissions and product costs. After the production of the barrier material, the coating process and the end-of-life handling scenarios were analysed, it emerged that starch had the lowest environmental impact and latex + kaolin had the highest. / Food packaging is required to secure the safety and quality of food, as well as minimize spoilage and simplify handling. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. This thesis focuses on the mass transport of oxygen in order to gain deeper knowledge of, and thereby optimise, the performance of barrier coatings. This experimental study, together with computer modelling, characterized the structure of barrier materials with respect to the mass transport process. The performance of the barriers was evaluated based on the parameters of environmental impact and product costs. As the long-term aim is to use non-petroleum-based barrier coatings for packaging, these should be evaluated by assessing the properties of the material in question, its functionality and its environmental impact to provide more insight into which materials are desirable as well as to develop technology. The results from this study indicate that several parameters (the orientation, concentration and aspect ratio of the clay and the polymer crystallinity) influence the properties of a barrier. Using this knowledge, researchers and food packaging engineers can work toward improving and customising renewable barriers. / VIPP

Converting wood into paper is a complex process involving many different stages, one of which is pulping. Pulping involves liberating the wood fibres from each other, which can be done either chemically or mechanically. This thesis focuses on the most common chemical pulping method, the kraft cooking process, and especially on a recently developed improvement of the impregnation phase, which is the first part of a kraft cook. Extended impregnation kraft cooking (EIC) technique is demonstrated to be an improvement of the kraft pulping process and provides a way to utilize softwood to a higher degree, at higher pulp yield. We demonstrate that it is possible to produce softwood (Picea abies) kraft pulp using a new cooking technique, resulting in a pulp that can be defibrated without inline refining at as high lignin content as 8% on wood, measured as kappa numbers above 90. Lignin is the wood constituent that holds the wood fibres together in the wood matrix. The new cooking technique uses the differences in reaction rate between the diffusion and consumption of hydroxide ions; it is used to ensure a homogenous impregnation of wood chips at lower impregnation temperatures and longer impregnation times than are generally used in the industry. The applied cooking temperatures are also substantially lower than those used in conventional kraft pulping systems, promoting uniform delignification. This results in a narrower kappa number distribution than in lab-cooked conventional kraft pulp. High-kappa-number pulps were investigated for pulp sheet properties such as tensile strength, tensile stiffness, and compression strength. It was demonstrated that an EIC pulp of kappa number 95 has strength properties comparable to those of a conventional pulp of kappa number 82. Comparing the effects of starch multilayers on conventional and EIC pulps reveals similar effects. The use of the starch multilayer treatment increased the tensile index and decreased the tensile stiffness and short-span compression test (SCT) indices. The EIC technique has also been used to produce a series of bleachable-grade pulps. The results indicate the possibility of increasing the lignin content of the pulp entering the oxygen delignification stage, since the reject content of gently defibered pulp is lower than 0.1% at kappa number 49. In this thesis, we recommend that wood chips be impregnated for 2 h at 110 °C to neutralize acidic compounds in the wood and impregnate the chips with cooking chemicals, and that the ensuing cook be performed at 135–140 °C, depending on the target kappa number. We also recommend increasing the available amounts of cooking chemicals in the impregnation stage by using a higher liquor-to-wood ratio and keeping the alkali profile fairly high in the ensuing cook. This concept will reduce the amount of reject material, increase the pulping uniformity, and increase the selectivity towards lignin degradation in the kraft cook. / Omvandling av ved till papper är en komplicerad process som består av många olika steg där ett är massaframställningen (eng. pulping). Massaframställning medför att vedfibrerna frigörs från varandra på kemisk eller mekanisk väg. Denna avhandling fokuserar på den vanligaste kemiska metoden, sulfatkokning och speciellt den nyligen utvecklade förbättringen av impregnerings fasen, som är den första delen av ett sulfatkok. Här visas att Extended Impregnation kraft Cooking (EIC) innebär en förbättring av sulfatkokningen och ett sätt att uppnå högre vedutnyttjande vid högre utbyte för barrved. Vi visar att det är möjligt att producera barrvedsmassa med en ny kokningsprincip som resulterar i en massa som är defibrerbar utan inline-raffinering vid så högt lignin innehåll som 8% (på ved), mätt som kappatal över 90. Lignin är den vedkomponent som håller ihop vedfibrerna i vedmatrisen. Kokningsprincipen utnyttjar skillnaderna i reaktionshastighet mellan diffusion och konsumtion av hydroxidjoner och nyttjas till att skapa en homogen impregnering av vedflisen vid lägre impregneringstemperatur och under längre tid än vad som vanligen används i industrin. De använda koktemperaturerna är också betydligt lägre än vid konventionell sulfatkokning vilket gynnar jämn delignifiering. Detta resulterar i en smalare kappatalsfördelning jämfört med laboratoriekokade konventionella massor. Massor med höga kappatal undersöktes med avseende på egenskaper hos handark, såsom dragstyrka, dragstyvhet och kompressionsstyrka Det visades att handark från EIC massa vid kappatal 95 hade jämförbara styrkeegenskaper med konventionell massa vid kappatal 82. Vid jämförelse av effekten av stärkelse multilager på konventionella och EIC massor avslöjar liknande effekter. Användningen av stärkelsemultilager ökade dragindex och minskade dragstyvhets- och kompressions index (SCT, short-compression test). Kokprincipen har även använts för att ta fram en serie blekbara massor. Resultaten visar på möjligheten att öka lignininnehållet i massan in till i syrgasdelignifierings-steget eftersom spetinnehållet för milt defibrerad massa var lägre än 0,1% vid kappatal 49. I den här avhandlingen rekommenderar vi att vedflis impregneras i 2 timmar vid 110 °C för att neutralisera sura komponenter i veden och impregnera flisen med kokkemikalier, samt att utföra det efterföljande koket vid 135–140 °C beroende på önskat kappatal. Vi rekommenderar även att öka den tillgängliga mängden kokkemikalier i impregneringssteget genom att använda högre vätske-ved förhållande och att hålla alkali profilen relativt hög i det efterföljande koket. Detta koncept reducerar spetmängden, ger jämnare kokning och ökar selektiviteten för nedbrytning av lignin i sulfatkoket. / QC 20120216