Cellulose and hemicelluloses have attracted increasing interest as renewable biopolymers because of their abundance. Furthermore, the recognition of biomass as a sustainable and renewable source of biofuels has driven research into the assembly and disassembly of polymers within plant cell walls. Cellulose thin films are useful in the study of interactions between cellulose and hemicelluloses, and quartz crystal microbalances with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and atomic force microscopy (AFM) are widely used to investigate polymer adsorption/desorption at liquid/solid interfaces. In this study, smooth trimethylsilyl cellulose (TMSC) films were spincoated onto gold QCM-D sensors and hydrolyzed into ultrathin cellulose films upon exposure to aqueous HCl vapor. The adsorption of arabinoglucuronoxylan (AGX) and arabinoxylan (AX) onto these cellulose surfaces was studied. The effects of structure, molar mass and ionic strength of the solution were considered. Increasing ionic strength increased AGX and AX adsorption onto cellulose. While AGX showed greater adsorption onto cellulose than AX by QCM-D, the trend was reversed in SPR experiments. The combination of QCM-D and SPR data showed a greater amount of water was trapped within the AX films. Both adsorbed AGX and AX films were subsequently visualized by AFM. Images from AFM showed AGX and AX adsorbed as aggregates from water, while AGX and AX adsorbed from CaCl2 yielded smaller xylan particles with more numerous globular structures on the cellulose surfaces. Images from AFM of xylan films on bare gold surfaces also showed layers of uniform aggregates that were consistent with AX and AGX aggregation in solution. / Master of Science

The aim of the study was to find out the relationship between the DP and the tensile properties of different regenerated cellulose fibers. During the process to make regenerated cellulose fibers from wood, the reduction in DP of cellulose is a necessary process to enable fiber extrusion. The reduction of the DP is usually from 1000 to 350 (Coley 1953). The reduction in DP is necessary, first to make the cellulose soluble, and then further decrease in DP is required to control the viscosity of the solution to minimize the mechanical difficulties during processing faced. It is a fact that the reduction in DP is a compromise which is necessary, as reduction in DP means reduction in tensile properties of the fiber produced. The reduction in DP is optimized to make the process both processing and the final product more feasible. The relation in DP and the strength of the fibers is rather obvious i.e. higher the DP higher the tensile strength, but researchers have different views regarding the relationship. By the experiments performed by us we tried to come to a conclusion regarding the difference in opinions. Different types of regenerated cellulose fibers were collected from various sources. Both wet and dry tenacities of 19 different viscose, bamboo viscose, kupro viscose, modal and Tencel fibers were determined. The fiber linear density was also measured, but for some samples we had to take the fiber density value as provided by the manufacturer, due to the limitation of the instrument regarding the fiber length and low fiber linear density. Then out of all the samples 10 were selected (based on our and company’s interest). SEC analysis was used to determine the DP of the samples. These tests were not carried out by us but by MoRe Research. The results of both the analysis were gathered, analyzed and commented upon. / Program: Master Programme in Textile Technology

The objectives of the research are to establish the process of obtaining regenerated fibers and films from wood pulp and bagasse pulp with the ionic liquid 1-Butyl-3-methylimidazolium Chloride (BMIMCl) as a solvent; to study the impacts on tensile strength of different spinning parameters; to find the optimal spinning condition, and to obtain regenerated cellulose products with flame retardant properties. Solutions were obtained by dissolving cellulose (wood/bagasse) pulp into the BMIMCl. The solutions were extruded in a dry-jet and wet-spinning method using water as a coagulation bath. The obtained fibers were tested to evaluate the properties such as tensile strength, thermal property, thermal mechanical property, crystal order, and ionic liquid residue in obtained fiber. The orthogonal experiments were designed to find out the strongest affective variable and the optimal condition of the spinning process. The regenerated cellulose films with melamine resin or zinc oxide were obtained. Their flame retardant properties were tested. Cellulose fiber with melamine resin was also obtained. Thermo-gravimetric analyzer (TGA) was used to measure the thermal properties of obtained products, and to calculate their activation energies. Dynamic mechanical analysis (DMA) was used to determine the thermal mechanical properties of obtained fibers. Wide angle X-ray diffraction (WAXD) was used to measure the degree of crystallinity and degree of crystal orientation. The tensile strength was tested by a tensile machine. To evaluate the quantity of ionic liquid residue in the regenerated fibers, the instrumental methods of FT-IR and Mass Spectrometry were applied. Research results indicated increases in the degree of crystallinity and storage modulus under a higher fiber drawing speed. Both regenerated bagasse fibers and regenerated wood fibers had similar thermal properties. However, the regenerated bagasse fibers showed a higher degree of crystallinity and a higher tenacity than the regenerated wood fibers obtained under the same condition. The study also revealed water treatment would be helpful for eliminating the ionic residue in regenerated fibers. It was also found the concentration of cellulose in the BMIMCl solution affected the tensile strength of regenerated fiber mostly. Certain amount of melamine or zinc oxide nanoparticles contained in the cellulose matrix could improve the flame retardant property effectively. / text

The performance of regenerated cellulose (RC) films and capsules was investigated for their applications in oral controlled drug delivery. Regenerated cellulose films were prepared by non-solvent-mediated, phase inversion of native and depolymerized cotton linter solutions (methylolcellulose; cellulose dissolved in dimethyl sulfoxide/ paraformaldehyde solvent system) in water as well as by phase inversion of native cotton linter solutions in organic non-solvents followed by thermal annealing. These films were monolithic in dry state and formed porous structures when hydrated. Irrespective of the degree of polymerization of the starting cellulose source or the use of organic non-solvents, the cellulose chain length was not significantly altered and cellulose was in an amorphous state. Flux analysis in diffusion cells, using ethanol-water mixtures as the solvent medium, indicated that the films take up solvent to form porous routes for transport of solute. The amount of solvent uptake required to form these routes was greater for films prepared from depolymerized cotton linter. Ionic and hydrophobic solutes traverse the films using the porous pathways following hydration of the film. Blended RC films were prepared by combining native and depolymerized cotton linter solutions in varying ratios and phase-inverting in water, followed by thermal annealing. Porosity, pore size and water uptake of the hydrated films decreased, while the length of the transport pathway (tortuosity) increased, as the fraction of depolymerized cellulose increased in the blended films. Differences in methylene blue dye adsorption on phase-inverted vs. phase-inverted and thermally annealed RC films indicated that the type of non-solvent utilized for phase-inversion does not affect the internal RC film structure during the phase-inversion process. However, as the boiling point of the non-solvent increased, the amount of irreversible polymer consolidation and formation non-swelling domains (hornification) increased during the thermal annealing process. This, in turn, led to reduced porosity and solute flux through these RC films. Two-piece cellulose capsules were fabricated by phase-inversion of methylolcellulose solutions in water using a dip-coating approach. Zero-order release rates for a number of drugs increased as their water solubility increased. The release of water soluble drugs occurred by osmotically-driven convection and diffusion through the pores in the capsule wall, while the release of moderate to poorly soluble drugs predominantly occurred by diffusion. Moreover, as the drug solubility increased, the apparent permeability of the drugs through the capsule wall decreased, which indicated that the inward osmotic flux of water reduced the diffusivity of the drug through the pores. The hydraulic permeability of the cellulose capsules was determined to be higher than for conventional ethylcellulose and cellulose acetate coated osmotic drug delivery systems, indicating that the cellulose-based capsules may be better suited for osmotic drug delivery.

Biobased all-cellulose composites (ACCs), in which the matrix and the reinforcement are made out of the same material, have gained a noticeable increased attention in recent years. Their successful application would solve the commonly faced challenges with natural fiber composites regarding their chemical antipathy between the hydrophilic fiber and the usually hydrophobic polymer matrix, while still keeping the advantages of being environmental friendly. Moreover, the use of man-made continuous regenerated cellulose fibers for this purpose could result in unidirectional all-cellulose composites with excellent mechanical properties. In this study, a new processing technique for unidirectional all-cellulose composites, reinforced with continuous regenerated cellulose nanocomposite fibers, has been developed, where the fibers are wound directly after the coagulation bath and then welded together while still being swelled in order to form all-cellulose composite sheets without the need of adding any additional solvent or chemicals. Scanning electron microscopy and tensile testing were used to investigate and compare the microstructure and mechanical properties, of a reference material without nanoreinforced fibers and two variants reinforced with 2 % cellulose nanocrystals (CNCs) and 2 % halloysite nanotubes (HNTs). Analysis revealed that transparent all-cellulose composites with a high compaction degree and minimal warpage during shrinkage, showing high mechanical properties could be made. However, the addition of nanoreinforcements did not lead to any improvements.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Chemistry, Durban University of Technology, Durban, South Africa, 2015. / This thesis forms part of the Council for Scientific and Industrial Research, Forestry and Forest Products Research Centre (CSIR-FFP) biorefinery project which aims at developing and implementing novel industrial processes production of cellulose textile fibres. The focus of this study is to investigate the dissolution of South African Eucalyptus raw (unbleached) and final (bleached) dissolving pulp and saw dust wood in an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and the co-solvents [dimethylsulfoxide (DMSO)] or [dimethylformamide (DMF)] mixtures, to obtain regenerated cellulose by the further addition of water and acetone. The IL/co-solvent mixtures were able to dissolve the raw and final pulp samples at 120 ˚C for 6 hours whereas the sawdust wood dissolved in 10 hours. The IL/DMF mixture gave higher cellulose recoveries of 41.88 % for the raw pulp, 49.89 % for the final pulp sample and 32.50 % for sawdust wood while the IL/DMSO mixture gave a recovery of 15.25 % for the raw pulp sample, 36.25 % for the final pulp sample and 17.83 % for the sawdust wood sample. The regenerated cellulose materials were characterized by Fourier Transformer Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Thermo gravimetric Analysis (TGA) and Powder X-Ray Diffraction (pXRD), and compared with a standard microcrystalline of cellulose. It was observed that the FTIR and NMR spectra of the regenerated cellulose and MCC were similar which then indicates that no chemical reaction occurred during the dissolution and regeneration process of cellulose. SEM and X-ray diffraction (XRD) patterns of the results showed that after dissolution the cellulose I (native form), the crystalline structure was completely converted into cellulose II (amorphous) structure, and this was due to the removal of lignin and decrease in cellulose crystallinity. TGA results showed that the regenerated cellulose samples have higher char yields compared to the MCC which is due to the IL remaining in the regenerated cellulose. It was also observed that the addition of the co-solvents decreased the viscosity of the IL mixture, facilitating dissolution of the cellulose that led to additional swelling and reduction of the recalcitrant nature of the cellulose crystalline structure and intermolecular interactions. This led to increased accessibility and dissolution of the cellulose. The findings in this study have the potential to bring ILs closer to applications for biomass technology in particular for an economically viable dissolution method for biomass because ILs have a benefit of being easily separated from the anti-solvent, which provides a simple solution for IL recycle ability and re-use. The novel aspect of this study is: . This is the first study in the South African context to examine the influence of the lignin on the dissolution and regeneration of Eucalyptus sawdust wood and dissolving pulp. / D

Modern chemical technology is an efficient tool for solving problems, particularly within the complex environment of the pulp and paper industry, and the combination of experimental studies, mill data and mass balance calculations are of fundamental importance to the development of the industry. In this study various examples are presented, whereby chemical technology is of fundamental importance. It is well documented that under normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without problems. However, in the case of  alternatives to the kraft recovery boiler, knowledge of more precise data of the molten salts is required for the design calculations. In this study the viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at temperatures relevant for a recovery boiler, i.e. similar to water at room temperature. The presence of non-process elements (NPE) in a typical pulp mill has been investigated. The main input is with regards to the wood, and anticipated problems include; deposits in evaporators, high dead-load in liquor streams, plugging of the upper part of the recovery boiler and decreasing efficiency in the causticization department. Efficient green liquor clarification is of the greatest importance as an efficient kidney for many NPE. Mill data and calculations show that the magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be highly beneficial. The prehydrolysis liquor will contain both sugars and acetic acid. It is however not possible to fully replace the sulphuric acid of the viscose spinning bath with acetic acid of own production. The sulphuric chemicals from the viscose plant can be partly taken care of in the kraft recovery area as well as the viscose plant which can be supplied with alkali and sulphuric acid. Zinc-containing effluents from the viscose plant can be treated with green liquor to precipitate zinc sulphide. / Modern chemical technology is an extremely efficient tool for solving problems particularly in a complicated environment such as the pulp and paper industry. Here, examples are studied during which chemical technology is of fundamental importance. At normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without hindrance. However, for certain kraft recovery boiler alternatives, knowledge of more precise data of the molten salts is required. The viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at relevant temperatures. The main input of non-process elements (NPE) is down to the wood, and known problems include deposits in evaporators and decreasing efficiency in the causticization department. Green liquor clarification is an efficient kidney for many NPE. Magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be of significant interest, as the handling of both alkali and sulphuric compounds can be integrated. Problems will however arise as the capacity of the pulping line and the chemical recovery has to be adjusted.

The structure and composition of denim jeans is complex. In addition to cotton, which is the dominating type of textile fibre, there may be up to about 20 % synthetic fibres. The synthetic fibres are found in the sewing thread and in the elastic yarns that are used to make stretch denim jeans. In total it was found that up to six different types of textile fibres may be present in the material. To be able to recycle cotton in jeans by producing regenerated cellulose fibres a very high purity with respect to cotton is required. The purpose with this project was to investigate the possibility to fractionate the textile material found in denim jeans to obtain a pure cotton fraction that can be used in the viscose process to produce regenerated cellulose fibres, which then can be used to manufacture new clothes. In this project traditional wet mechanical separation equipment found in the pulp and paper industry, in the form of a laboratory screen (used as a model for a pressure screen) and hydrocyclone, was used to fractionate the textile material from cut and shredded denim jeans. The degree of separation of synthetic fibres from cotton fibres was quantitatively evaluated by measuring the glucose content after acid hydrolysis. The results from the experimental work showed that there were runnability problems both regarding disintegration and fractionation. Regarding the fractionation, plugging was found to be a problem and no significant separation of synthetic fibres from cotton fibres was obtained with the conditions of the experiment. / Strukturen och sammansättningen i denimjeans är komplex. Utöver bomull, vilken är den dominerande typen av textilfiber, kan de innehålla upp till 20 % syntetiska fibrer i tyget. De syntetiska fibrerna finns i sytråden och i elastiska garner som används för att tillverka stretchdenimjeans. Den här studien visade att upp till sex olika typer av textilfibrer kan förekomma i materialet. För att kunna återvinna bomull i denimjeans genom att producera regenererade cellulosafibrer krävs en mycket hög renhet med avseende på bomull. Syftet med projektet var att undersöka möjligheten att fraktionera textilmaterialet i denimjeans för att erhålla en ren bomullsfraktion som kan användas i viskosprocessen för att tillverka regenererade textilfibrer, vilka sedan kan användas för att tillverka nya kläder. I projektet användes, inom massa och pappersindustrin traditionell våtmekanisk separationsutrustning i form av en laboratoriesil (här använd som en modell av en trycksil) och en hydrocyklon, för att fraktionera textilmaterialet från klippta och sönderslitna denimjeans. Separationsgraden av syntetiska fibrer från bomullsfibrer bestämdes kvantitativt genom att mäta glukoshalten efter sur hydrolys. Resultatet från det experimentella arbetet visade att det finns körbarhetsproblem både gällande uppslagning och fraktionering. För fraktioneringen visade sig pluggning vara ett problem och ingen signifikant separation av syntetiska fibrer från bomullsfibrer erhölls med förhållandena i experimentet.

Naturskyddsföreningen gav författarna uppgiften att undersöka förekommande viskosprocesser och alternativa regenereringsprocesser, detta för att identifiera hur hållbara de är ur ett miljöperspektiv och vilka processer som går att applicera på bambu. Detta för att se möjligheten att märka bambuviskos med Bra Miljöval och för att klargöra frekvent uppkommande frågor angående bambuviskos. Syftet är att se på de olika processernas kemiska innehåll samt vilka utsläpp de orsakar till luft och vatten. Ett delmål med rapporten är att den ska kunna användas som material vid vidareutveckling av kriterierna för Bra Miljöval Textil. Resultat som erhållits vid jämförelser av studerad litteratur är att de betydande faktorerna för miljöpåverkan från massaframställningen samt viskos- och lyocellprocessen beror av: använda kemikalier i processen, energianvändningen och vilken typ av energi, möjligheten till rening av utsläpp till luft och vatten samt återvinning av energi och kemikalier. Beroende på vilket råmaterial som används vid massaframställningen kan skillnader i markanvändning, användning av bekämpningsmedel och gödningsmedel samt upptagande av koldioxid skilja sig. Massa- och fiberframställning bör vara integrerade då energiförbrukning och mängd kemikalier kan minskas. Energin kan dessutom återvinnas till större utsträckning.Genom miljömärkningar från oberoende organisationer blir det lättare för konsumenter att göra miljömedvetna val och veta vad märkningarna står för. Sammanfattningsvis ska det påpekas att om regenererad bambu framställs som den görs idag är den ingen hållbar fiber, men sker framställningen i en integrerad process där kemikalier och energi återvinns samt rening av utsläpp till luft och vatten sker, kan bambuviskos bli en hållbar fiber för framtiden. The Swedish Society for Nature Conservation (SSNC) gave the authors the task to investigative present viscose processes and alternative regeneration processes to identify how sustainable they are from an environmental perspective, and examine which processes that can be applied to bamboo. This to see the possibility to label bamboo viscose with “Bra Miljöval” (Good Environmental Choice), which is the eco-label of SSNC, and to clarify the frequently emerging issues concerning bamboo viscose. The aim is to look at the various processes, their chemical content and the emissions they cause to air and water. Another objective of the report is that it can be used as material for further development of the criteria for “Bra Miljöval”.Results obtained when comparing the studied literature is that the significant factors of the environmental impact from the pulp production, the viscose and lyocell processes depends on: chemicals used in the process, energy and energy source, the possibility of purifying emissions to air and water and recycling of energy and chemicals. Depending on the raw materials used for pulp production, differences in land use, use of pesticides and fertilizers as well as absorption of carbon dioxide differ. Pulp and fibre production should be integrated to reduce energy consumption and the amount of chemicals used. The energy can also be recycled to a greater extent.Eco-labels from independent organizations will make it easier for consumers to make environmentally conscious choices and be aware of what the labels stand for.In conclusion, it should be noted that if the regenerated bamboo is produced as it is today, it is not a sustainable fibre. If the production is done through an integrated process in which chemicals and energy recovery and purification of air and water occurs, bamboo viscose can be a sustainable fibre for the future. / Program: Textilingenjörsutbildningen