| 1. |
- Bylin, Susanne, 1982
(författare)
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Mechanisms of Biopolymer Solvation: Development of a two-component ionic liquid solvent system
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ionic liquids are of potential interest in the processing of lignocellulosic biomass, and/or its components, for the purpose of producing renewable and value-added biomaterials. An understanding of how solvation can be achieved and the way in which the feedstock biopolymers are affected, however, needs to be gained prior to a viable implementation. In this thesis, the solvation of the wood biopolymers cellulose, xylan and lignin in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIMAc) in a novel combination with the second system component 1-methylimidazole (MIM) have been investigated:The solvation of dissolving pulp, beech xylan and LignoBoost lignin model materials, was studied using FBRM (focused beam reflectance measurements) particle characterization in combination with microscopic analysis (cellulose and xylan), determination of molecular weights (xylan and lignin) and 13C- and 31P-NMR (nuclear magnetic resonance spectroscopy) of lignin.It was concluded that the most efficient solvation of cellulose and xylan occurred using 3-4% and 9% IL (n/n anhydroglucose units and n/n anhydroxylose Units), respectively, while polymer integrity was maintained. Cellulose solvation was found to be greatly dependent on the IL to AGU ratio whereas xylan solvation varied greatly with temperature. Moreover, a theoretical model was developed for the solvation of cellulose in the present system. The solvation of lignin was achieved at ~20% lignin loading (w/w), in any combination of MIM/EMIMAc. Regeneration of lignin resulted in two sets of fractions; one exhibiting a general and higher apparent molecular weight (Mw) along with an enrichment of condensed/aliphatic ether linkages and aliphatic hydroxyls, and the other exhibiting a lower apparent Mw and an enrichment of carboxylic and phenolic groups. The knowledge of biopolymer solvation gained in the present solvent system provides future opportunities of tuning extraction and/or fractionation processes to suite the specifications of a particular biomass-derived product.
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| 2. |
- Andersson, Helene, 1983, et al.
(författare)
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Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
- 2013
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
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Tidskriftsartikel (refereegranskat)abstract
- Films of ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be used for extended release coatings in oral formulations. The permeability and microstructure of free EC/HPC films with 30% w/w HPC were studied to investigate effects of EC molecular weight. Phase separation during film spraying and subsequent HPC leaching after immersion in aqueous media cause pore formation in such films. It was found that sprayed films were porous throughout the bulk of the films after water immersion. The molecular weight affected HPC leaching, pore morphology and film permeability; increasing the molecular weight resulted in decreasing permeability. A model to distinguish the major factors contributing to diffusion retardation in porous films showed that the trend in permeability was determined predominantly by factors associated with the geometry and arrangement of pores, independent of the diffusing species. The film with the highest molecular weight did, however, show an additional contribution from pore wall/permeant interactions. In addition, rapid drying and increasing molecular weight resulted in smaller pores, which suggest that phase separation kinetics affects the final microstructure of EC/HPC films. Thus, the molecular weight influences the microstructural features of pores, which are crucial for mass transport in EC/HPC films.
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| 3. |
- Bashir, Tariq
(författare)
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Conjugated Polymer-based Conductive Fibers for Smart Textile Applications
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electrically conductive or electro-active fibers are the key components of smart and interactive textiles, which could be used in medical, sports, energy, and military applications in the near future. The functionalization of high-performance textile yarns/fibers with conjugated polymers can produce conductive fibers with better electro-mechanical properties, which is difficult with commonly used spinning techniques. In this thesis work, textile-based conductive yarns/fibers were prepared by coating viscose and polyester (PET) yarns with the conjugated polymer PEDOT. For coating purposes, an efficient technique called chemical vapor deposition (CVD) was used, which is a solventless technique and can produce PEDOT polymer layers with high conductivity values. The polymerization of EDOT monomer vapors and coating of oxidant (FeCl3 or FepTS) enriched viscose and PET yarns took place simultaneously. The PEDOT-coated viscose and polyester yarns showed relatively high conductivity values, which could be sufficient for many electronic applications. The polymerization process and the quality of PEDOT polymer strongly depends on different reaction conditions. In this research work, the impact of most of these reaction parameters on the electrical, mechanical, and thermal properties of PEDOT-coated conductive yarns was considered separately. Under specific reaction conditions, it was found that viscose fibers were successfully coated with PEDOT polymer and showed rather high electrical conductivity (≥ 15 S/cm). However, due to the acid hydrolysis of viscose fibers in FeCl3 solutions, the mechanical properties were drastically reduced. In order to improve the mechanical properties of conductive yarns, a relatively stable and chemical-resistant substrate (PET) was coated with PEDOT polymer. Comparative studies between PEDOT-coated viscose and PET conductive yarns showed that the electrical and mechanical properties were enhanced by changing the substrate material. Later on, PEDOT-coated conductive fibers were treated with silicone elastomer solution and due to the thin silicone layers, the hydrophobic properties, flexibility, and durability of coated yarns was improved. Furthermore, a novel electrical resistance-measuring setup was developed, which can be used not only for fibers but also for fabric structures. The electrical characterization of PEDOT-coated conductive yarns showed that it can be used effectively for sensitive fibers without damaging their surface morphology. Finally, the use of conductive yarns as stretch sensors was evaluated. For this purpose, small rectangular knitted patches of conductive yarns were prepared and then the change in electrical resistance values at different extension percentages (5–50%) was investigated. The constant variations in electrical resistance values at different extension and relaxation cycles for longer periods of time revealed that the conductive yarns produced have the potential to be used as stretch sensors for monitoring of vital signs in medical and sports applications.
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| 4. |
- Bosmans, Toon, 1988, et al.
(författare)
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Assembly of Debranched Xylan from Solution and on Nanocellulosic Surfaces
- 2014
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 15:3, s. 924-930
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Tidskriftsartikel (refereegranskat)abstract
- This study focused on the assembly characteristics of debranched xylan onto cellulose surfaces. A rye arabinoxylan polymer with an initial arabinose/xylose ratio of 0.53 was debranched with an oxalic acid treatment as a function of time. The resulting samples contained reduced arabinose/xylose ratios significantly affecting the molecular architecture and solution behavior of the biopolymer. With this treatment, an almost linear xylan with arabinose DS of only 0.04 was obtained. The removal of arabinose units resulted in the self-assembly of the debranched polymer in water into stable nanoparticle aggregates with a size around 300 nm with a gradual increase in crystallinity of the isolated xylan. Using quartz crystal microbalance with dissipation monitoring, the adsorption of xylan onto model cellulose surfaces was quantified. Compared to the nonmodified xylan, the adsorption of debranched xylan increased from 0.6 to 5.5 mg m(-2). Additionally, adsorption kinetics suggest that the nanoparticles rapidly adsorbed to the cellulose surfaces compared to the arabinoxylan. In summary, a control of the molecular structure of xylan influences its ability to form a new class of polysaccharide nanoparticles in aqueous suspensions and its interaction with nanocellulose surfaces.
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| 5. |
- Fatarella, Enrico, et al.
(författare)
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Polymeric composition comprising functionalized PEEK
- 2014
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Patent (populärvet., debatt m.m.)abstract
- The present invention relates to a polymeric composition comprising functionalized polyetheretherketone (PEEK) of formula (II), in admixture with a co-polymer having a melting point lower than the melting point of the non-functionalized PEEK of formula (I). The invention further relates to the use of said composition for the preparation of fibers having antibacterial, decontaminant and self-cleaning properties, useful, for example, for making sanitary garments, such as sanitary coats and masks and for making, for example, filters for ventilation systems and filters for kitchen hoods.
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| 6. |
- Moriana, Rosana, et al.
(författare)
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Assessing the influence of cotton fibers on the degradation in soil of a thermoplastic starch-based biopolymer
- 2010
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Ingår i: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 31:12, s. 2102-2111
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Tidskriftsartikel (refereegranskat)abstract
- Biocomposites consisting of cotton fibers and a commercial starch-based thermoplastic were subjected to accelerated soil burial test. Fourier transform infrared (FTIR) spectrometry analysis was carried out to provide chemical-structural information of the polymeric matrix and its reinforced biocomposites. The effects that take place as a consequence of the degradation in soil of both materials were studied by FTIR-ATR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). When the polymeric matrix and the reinforced biocomposite are submitted to soil burial test, the infrared studies display a decrease in the C=O band associated to the ester group of the synthetic component as a consequence of its degradation. The crystalline index of both materials decreased as a function of the degradation process, where the crystalline structure of the reinforced biocomposite was the most affected. In accordance, the degraded reinforced biocomposite micrographs displayed a more damaged morphology and fracture surface than the degraded polymeric matrix micrographs. On the other hand, the same thermal decomposition regions were assessed for both materials, regardless of the degradation time. Kissinger, Criado, and Coats-Redfern methods were applied to analyze the thermogravimetric results. The kinetic triplet of each thermal decomposition process was determined for monitoring the degradation test. The thermal study confirms that starch was the most biodegradable polymeric matrix component in soil. However, the presence of cotton fiber modified the degradation rate of both matrix components; the degradability in soil of the synthetic component was slightly enhanced, whereas the biodegradation rate of the starch slowed down as a function of the soil exposure time. © 2010 Society of Plastics Engineers.
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| 7. |
- Nyflött, Åsa, 1986-
(författare)
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Structural Studies and Modelling of Oxygen Transport in Barrier Materials for Food Packaging
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The requirements of food packages are to ensure food safety and quality, to minimize spoilage, and to provide an easy way to store and handle food. To meet these demands for fibre-based food packages, barrier coatings are generally used to regulate the amount of gases entering a package, as some gases are detrimental to food quality. Oxygen, for example, initiates lipid oxidation in fatty foods. Bakery products may also be sensitive to oxygen.This thesis focused on mass transport of oxygen in order to gain deeper knowledge in the performance of barrier coatings and to develop means to optimize the performance of barrier coatings. This experimental study along with computer modelling characterized the structure of barrier materials with respect to the mass transport process.This project was performed as part of the multidisciplinary industrial graduate school VIPP (www.kau.se/en/vipp) - Values Created in Fibre Based Processes and Products – at Karlstad University, with the financial support from the Knowledge Foundation, Sweden, and Stora Enso.
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| 8. |
- Olsson, Carina, 1982, et al.
(författare)
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Dissolution and regeneration of wood saccharides in ionic liquids
- 2010
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Ingår i: Proceedings, 11th European Workshop of Lignicellulosics and Pulp. ; , s. 411-414
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cellulose is one of the most important sources of renewable biomaterials, but the number of solvents that are capable of dissolving cellulose is still today very limited. Among non-derivatizing solvents, there are even fewer alternatives. Imidazolium based ionic liquids make up a well studied group of solvents for cellulose that have many advantages such as being considered environmentally friendly, and relatively easy to recycle. Here a model substance of native cellulose, namely oligomeric cellulose with DP = 4.33 is used to study the interactions between cellulose and ionic liquid in solution using 1H NMR spectroscopy. It can be concluded that the oligocellulose is a suitable model substance, with a higher resemblance to polymeric cellulose than for example cellobiose that have previously been used but with maintained possibilities to give high resolution in 1H NMR spectres.
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| 9. |
- Barghi, Hamidreza, 1970, et al.
(författare)
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BULK HYDROPHILIC FUNTIONALIZATION OF POLYAMIDE 46
- 2013
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- A modified polymer as result of a bulk functionalization of polyamide 46 (PA 46) is presented, as well as methods for synthesizing the modified polymer. This functionalization of PA 46 is performed to provide a homogenous semi-permeable polyamide 46 capable of different charges and different porosities with particles of nanoscale size in order to replace or improve other polyamide fibers used in the textile industry, filtering processes, selective sorption, controlled release devices, phase transfer catalysts, chromatography media, biocompatible capsules, artificial skins, organs, bone void repair as well as in cell bioreactors and incubators, dental impliments, medical devices, clothing, detectors, perfusion devices, in regenerative medicine, and fuel cells.
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| 10. |
- Felix, J., et al.
(författare)
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P-61: Recycling and re-use of LCD components and materials
- 2010
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Ingår i: Digest of Technical Papers - SID International Symposium. - : Wiley. - 2168-0159 .- 0097-966X. ; 41, s. 1469-1472
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Konferensbidrag (refereegranskat)abstract
- Methods for extracting components and materials from waste liquid crystal displays have been developed. The methods enable the components to be extracted with their key properties preserved, thus qualifying them for re-use both in LCD and other applications. Novel applications for re-use of recycled LCD components have been developed in which the LCD components contribute with a substantial customer benefit.
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