| 1. |
- Andersson, Helene, 1983, et al.
(author)
-
Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
- 2013
-
In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
-
Journal article (peer-reviewed)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.
|
|
| 2. |
- Menzel, Carolin, et al.
(author)
-
Molecular structure of citric acid cross-linked starch films
- 2013
-
In: Carbohydrate Polymers. - Amsterdam : Elsevier. - 0144-8617 .- 1879-1344. ; 96:2, s. 270-276
-
Journal article (peer-reviewed)abstract
- The effect of citric acid (CA) on starch films has been examined. A new method to detect cross-linkingof starch by CA in solution-cast films by molecular weight measurements is described. Furthermore, wemanaged to distinguished between free, mono- and di-esterified CA and quantify di-ester content withinstarch films by using a modification in the method of complexometric titration with copper(II)-sulfate.Cross-linking of starch by CA occurred at low temperature, 70◦C, which we assumed is so far the lowesttemperature reported where cross-linking reaction occurred. This is essential for starch coating applica-tions within paper industry since no high temperatures for curing will be required. However, curing at150◦C and high CA concentrations, 30 pph, increased cross-linking reaction. Furthermore, the physicalproperties like water solubility, gel content and glass transition temperature, were highly reflected bychanges in the molecular structure i.e. cross-linking and hydrolysis, as well as CA content and curingtemperature.
|
|
| 3. |
- Bylin, Susanne, 1982
(author)
-
Mechanisms of Biopolymer Solvation: Development of a two-component ionic liquid solvent system
- 2014
-
Licentiate thesis (other academic/artistic)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.
|
|
| 4. |
- Felix, J., et al.
(author)
-
P-61: Recycling and re-use of LCD components and materials
- 2010
-
In: Digest of Technical Papers - SID International Symposium. - : Wiley. - 2168-0159 .- 0097-966X. ; 41, s. 1469-1472
-
Conference paper (peer-reviewed)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.
|
|
| 5. |
- Pardon, Gaspard, 1983-
(author)
-
From Macro to Nano : Electrokinetic Transport and Surface Control
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics.At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro- and nanotechnologies could also contribute.This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro- and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro- and nanoscale, towards applications in PoC diagnostics and ECS systems.At the macroscale, electrokinetic transport was applied to the development of a novel PoC sampler for the efficient capture of exhaled breath aerosol onto a microfluidic platform.At the microscale, several methods for polymer micromanufacturing and surface modification were developed. Using direct photolithography in off-stoichiometry thiol-ene (OSTE) polymers, a novel manufacturing method for mold-free rapid prototyping of microfluidic devices was developed. An investigation of the photolithography of OSTE polymers revealed that a novel photopatterning mechanism arises from the off-stoichiometric polymer formulation. Using photografting on OSTE surfaces, a novel surface modification method was developed for the photopatterning of the surface energy. Finally, a novel method was developed for single-step microstructuring and micropatterning of surface energy, using a molecular self-alignment process resulting in spontaneous mimicking, in the replica, of the surface energy of the mold.At the nanoscale, several solutions for the study of electrokinetic transport toward selective biofiltration and energy conversion were developed. A novel, comprehensive model was developed for electrostatic gating of the electrokinetic transport in nanofluidics. A novel method for the manufacturing of electrostatically-gated nanofluidic membranes was developed, using atomic layer deposition (ALD) in deep anodic alumina oxide (AAO) nanopores. Finally, a preliminary investigation of the nanopatterning of OSTE polymers was performed for the manufacturing of polymer nanofluidic devices.
|
|
| 6. |
- Bosmans, Toon, 1988, et al.
(author)
-
Assembly of Debranched Xylan from Solution and on Nanocellulosic Surfaces
- 2014
-
In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 15:3, s. 924-930
-
Journal article (peer-reviewed)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.
|
|
| 7. |
- Olsson, Erik, 1984-
(author)
-
Effects of Citric Acid on Starch-Based Barrier Coatings
- 2013
-
Doctoral thesis (other academic/artistic)abstract
- With growing environmental concerns, efforts are made to replace petroleum based products with renewable alternatives. This is particularly evident in the packaging industry, where replacing synthetic polymers with renewable materials is of considerable interest. Materials for food packaging need to give protection, acting as a barrier against substances that can adversely affect the food quality such as water and oxygen.In this work, barrier dispersion coatings based on starch were used to produce coated papers which act as barrier against water and oxygen. However, since starch is both a hydrophilic and hygroscopic material, this barrier material becomes problematic to use at high relative humidity. In order to reduce this problem and improve the barrier properties enabling starch based barrier materials to be used in food packaging applications, two approaches were studied.Citric acid was utilized as a cross-linker of the starch and it was found to reduce the moisture sorption, the molecular movement and swelling at high relative humidity. It was seen that cross-linking and hydrolysis due to the low pH both affected the barrier properties significantly, but in opposing directions. By controlling these two reactions it was seen that this could lead to reduced gas permeability. It was also seen that cross-linking of starch by citric acid occurs at low temperatures, 70 °C at pH as high as 6.5.Starch nano-composites were produced by incorporating montmorillonite, to the barrier dispersion to improve the barrier properties. It was seen that the suspension viscosity was reduced by poly(ethylene glycol) and citric acid adsorption on the montmorillonite particles. Also, a tendency for improved barrier properties with reduced aggregate volume fraction and reduced swelling was observed. It was also seen that up scaling this formulation to pilot scale was possible and that promising results were achieved.
|
|
| 8. |
- Olsson, Erik, 1984-, et al.
(author)
-
Influence of citric acid and curing on moisture sorption, diffusion and permeability of starch films
- 2013
-
In: Carbohydrate Polymers. - Amsterdam : Elsevier BV. - 0144-8617 .- 1879-1344. ; 94:2, s. 765-772
-
Journal article (peer-reviewed)abstract
- Starch films with different amounts of citric acid produced by solution casting were subjected to different curing temperatures and compared with films plasticized with glycerol. The films were tested in a controlled moisture generator, which enabled the moisture sorption to be measured and the diffusion coefficient and water vapor permeability to be calculated. It was shown that increasing the amount of citric acid added led to a reduction in the equilibrium moisture content, diffusion coefficient and water vapor permeability of the films, the values of which were all considerably lower than the values obtained for the films plasticized by glycerol. It was also seen that curing the film with 30 pph citric acid at 150 degrees C led to a significant reduction in the equilibrium moisture content, the diffusion coefficient and the water vapor permeability at high relative humidity which suggests that crosslinking occurred. The calculated water vapor permeability data were comparable with the value obtained with direct measurements.
|
|
| 9. |
- Olsson, Erik, 1984-, et al.
(author)
-
Montmorillonite clay for starch-based barrier dispersion coating : Part 2 Pilot trials and PE-lamination
- 2014
-
In: Applied Clay Science. - Amsterdam : Elsevier. - 0169-1317 .- 1872-9053. ; 97-98, s. 167-173
-
Journal article (peer-reviewed)abstract
- Montmorillonite clays have been shown to improve the barrier properties of thermoplastic starch coatings. In this paper, it is shown that it is possible to scale-up a recipe containing poly(ethylene glycol)-plasticized starch and a citric acid-dispersed montmorillonite to pilot scale and to achieve water vapor barrier properties which are comparable to those achieved in laboratory scale. The results are compared with those obtained with two commercial synthetic barrier dispersions. The combination of a polyethylene film laminated on top of a 3 g/m2 starch-based coating showed the potential to give also oxygen barrier properties to the multilayer structure when applied on a paper substrate.
|
|
| 10. |
- Olsson, Erik, 1984-, et al.
(author)
-
Montmorillonite clay for starch-based barrier dispersion coating : Part 1 The influence of citric acid on viscosity and barrier properties
- 2014
-
In: Applied Clay Science. - : Elsevier. - 0169-1317 .- 1872-9053. ; , s. 160-166
-
Journal article (peer-reviewed)abstract
- Starch-based coating formulations were draw-down coated on a paper substrate and the effect on the water vapor transmission rate, WVTR, upon montmorillonite addition was compared to that of the pure the starch matrix without added plasticizer and for poly(ethylene glycol), PEG, and citric acid, CA, as potential plasticizers. Both potential plasticizers were added at a ratio of 3 to 10 to starch. Addition of CA to the starch solution substantially lowered the WVTR of the coated papers compared to coating with a pure starch or PEG-plasticized coating. The WVTR of the papers coated with starch and CA was lower than that obtained for paper coated with non-plasticized montmorillonite-starch dispersions, and approximately similar to paper coated with montmorillonite-starch dispersions plasticized with PEG or with citric acid. Addition of montmorillointe was effective in reducing the WVTR in the case of PEG-plasticized starch but not in the case of CA. These differences in WVTR were indicated to be due to differences in the viscosity and the clay swelling indicating that CA and PEG affected the state of dispersion differently. CA was also investigated as a dispersing agent by addition in small quantities to the montmorillonite dispersion at different pH values. When this clay dispersion was added to a suspension already containing PEG, CA gave slightly reduced plastic viscosity and there was also a weak correlation between low plastic viscosity and WVTR.
|
|
