The potential use of renewable, bio-based polymers in high-technological applications has attracted great interest due to increased environmental concern. Cellulose is the most abundant biopolymer resource in the world, and it has great potential to be modified to suit new application areas. The development of controlled polymerization techniques, such as atom transfer radical polymerization (ATRP), has made it possible to graft well-defined polymers from cellulose surfaces. In this study, graft-modification of cellulose substrates by ATRP was explored as a tool for tailoring surface properties and for the fabrication of functional cellulose surfaces. Various native and regenerated cellulose substrates were successfully graft-modified to investigate the effect of surface morphology on the grafting reactions. It was found that significantly denser polymer brushes were grafted from the native than from the regenerated cellulose substrates, most likely due to differences in surface area. A method for detaching the grafted polymer from the substrate was developed, based on the selective cleavage of silyl ether bonds with tetrabutylammonium fluoride. The results from the performed kinetic study suggest that the surface-initiated polymerization of methyl methacrylate from cellulose proceeds faster than the concurrent solution polymerization at low monomer conversions, but slows down to match the kinetics of the solution polymerization at higher conversions. Superhydrophobic and self-cleaning bio-fiber surfaces were obtained by grafting of glycidyl methacrylate using a branched graft-on-graft architecture, followed by post-functionalization to obtain fluorinated polymer brushes. AFM analysis showed that the surface had a micro-nano-binary structure. It was also found that superhydrophobic surfaces could be achieved by post-functionalization with an alkyl chain, with no use of fluorine. Thermo-responsive cellulose surfaces have been prepared by graft-modification with the stimuli responsive polymer poly(N-isopropylacrylamide) (PNIPAAm). Brushes of poly(4-vinylpyridine) (P4VP) rendered a pH-responsive cellulose surface. Dual-responsive cellulose surfaces were achieved by grafting block-copolymers of PNIPAAm and P4VP. / QC 20100804

Solvent-borne thermally cured coil-coating resins contain large amounts of volatile organic solvents in order to obtain suitable flow for film application. This work describes how the expensive and environmental hazardous volatile organic solvent content of a solvent-borne thermally cured polyester/melamine coil-coating system can be reduced by introduction of fatty acid methyl esters (FAMEs) as reactive diluents and modification of the polyester binder resin. The evaluated reactive diluents, two rape seed methyl esters (RMEs), two linseed oil methyl esters (LMEs), and a tall oil methyl ester (TOME) have been evaluated both in a fully formulated clear-coat system and via model studies. Viscosity measurements of wet paint mixtures showed that formulations with hyperbranched polyester binder hold lower viscosity than conventional polyester binder resins and that FAME works as a diluent. Fully formulated clear-coats were cured under simulated industrial coil-coating cure conditions and in a convection oven at lower temperatures respectively. FAME increases the mobility of the system enhancing the film formation process. Free-standing clear-coat films were analyzed with Raman, carbon-14 dating, extraction, dynamic mechanical analysis, and visual observation. Incorporation of FAME could not be confirmed by Raman analysis. However, carbon-14 dating indicated the presence of FAME that could not be extracted from the films. The mechanical properties of the films were also affected by the addition of FAMEs, oven temperature, choice of co-solvent, and flash-off period. Conventional film characterization tests on substrate supported coatings indicated that binder resin structure and cure conditions affect the final film properties. Model studies were performed to clarify how FAME can chemically react through transesterification with the hydroxyl-groups of the polyester. The transesterification reaction between different FAMEs and primary alcohols with and without tertiary hydrogen was monitored with 1H-NMR and real time IR. Evaporation and side reactions, e.g. alkene reactions, are competing factors to the transesterification reaction. The study showed that fatty acid structure, reaction time, and temperature affect the transesterification conversion, degree of side reactions, and choice of catalyst. A pigmented fully formulated polyester/melamine formulation with a reactive diluent was cured at full scale in an industrial coil-coating production facility. Evaluation of the final film properties showed that the coating fulfills the specification of conventional polyester/melamine coil-coating systems. / QC 20100817

The diffusion of small-molecule penetrants in polyethylene is hindered by impenetrable crystals and by the segmental constraints imposed by the crystals on the penetrable phase. Liquid and vapour n-hexane sorption/desorption measurements were performed on metallocene catalyzed homogenous poly(ethylene-co-octene)s. It was shown that the fractional free volume of the polymer penetrable component increased with increasing amount of penetrable polymer. It also increased with the relative proportion of liquid-like component in the penetrable polymer fraction. The detour effect was found to increase with decreasing crystallinity. The experimental study of the morphology of the polymers showed that the geometrical impedance factor followed the same trend with increasing crystallinity as the data obtained from n-hexane desorption. The changes in phase composition and character upon n-hexane sorption were monitored with Raman spectroscopy, WAXS and NMR spectroscopy. Partial dissolution of the orthorhombic and the interfacial component was observed upon nhexane sorption. Changes in the character of the components were furthermore analyzed: an increase of the density in the crystalline component and a decrease of the density in the amorphous component were observed in the n-hexane-sorbed-samples. Molecular dynamics simulations were used for studying diffusion of n-hexane in fully amorphous poly(ethylene-co-octene)s. The branches in poly(ethylene-co-octene) decreased the density by affecting the packing of the chains in the rubbery state in accordance with experimental data. Diffusion of n-hexane at low penetrant concentration showed unexpectedly that the penetrant diffusivity decreased with increasing degree of branching. Spherulitic growth was mimicked with an algorithm able to generate structures comparable to those observed in polyethylene. The diffusion in the simulated structure was assessed with Monte Carlo simulations of random walks and the geometrical impedance factor of the spherulitic structures was calculated and compared with analytical values according to Fricke’s theory. The linear relationship between geometrical impedance factor and crystallinity in Fricke’s theory was confirmed. Fricke’s theory, however, underestimated the crystal blocking effect. By modelling systems having a distribution of crystal width-to-thickness ratio it was proven that wide crystals had a more pronounced effect on the geometrical impedance factor than is indicated by their number fraction weight. / QC 20100909

<p>A uniaxial High-Velocity Compaction (HVC) process for polymer powder using a cylindrical, hardened steel die and a new technique with relaxation assist was tested with a focus on the compactibility characteristics and surface morphology of the compacted materials using various heights of relaxation assist device with different compacting profiles.</p><p>Relaxation assist device was presented as a new technique to reduce springback, pull-out phenomenon and to improve the compaction process.</p><p>The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain pull-out phenomenon during the decompacting stage. In this study, polyamide-11 powders with different particle size distributions have been compacted with the application of different compaction profiles, e.g. different energies and velocities. It was found that the relative green density is influenced more by the pre-compacting (primary compaction step) than by the post-compacting (secondary compaction step).</p><p>Experimental results for different compaction profiles were presented showing the effect of varying the opposite velocity during the decompacting stage and how to improve the homogeneous densification between the upper and lower surface and the evenness of the upper surface of the compacted powder bed by using relaxation assists, and the influences of the relaxation assist device on the process characteristics. It was found that the relaxation assist improves the compaction of the polymer powder by locking the powder bed in the compacted form. In addition, the relative times of the compacting stage, decompacting stage and the reorganisation of the particles can be controlled by altering the height of the relaxation assist. It was found that the high-velocity compaction process is an interruption process and that the delay times between the pressure waves can be reduced by increasing the height of the relaxation assist device. Furthermore, the first gross instantaneous springback and the total elastic springback are reduced.</p><p>Two bonding strain gauges and a high-speed video camera system were used to investigate the springback phenomenon during the compaction process. Scanning electron microscopy (SEM) and image computer board Camera (IC-PCI Imaging Technology) were used to the study the morphological characteristics, the limit of plastic deformation and particle bonding by plastic flow at contact points, and pull-out phenomena.</p> / QC 20100506

<p>Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. </p><p>The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment.</p><p>The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.</p>

Dynamic covalent chemistry (DCC) is currently exploited in several areas of biomedical applications such as in drug discovery, sensing, molecular separation, catalysis etc. Hydrazone and oxime chemistry have several advantages, such as mild reaction conditions, selectivity, efficiency, and biocompatibility and therefore, have the potential to be for bioconjugation applications. However, these reactions suffer from major drawbacks of slow reaction rate and poor bond stability under physiological conditions. In this regard, the work presented in this thesis focuses on designing novel bioconjugation reactions amenable under physiological conditions with tunable reaction kinetics and conjugation stability. The first part of the thesis presents different strategies of dynamic covalent reactions utilized for biomedical applications. In the next part, a detailed study related to the mechanism and catalysis of oxime chemistry was investigated in the presence of various catalysts. Aniline, carboxylate and saline were selective as target catalysts and their reaction kinetics were compared under physiological conditions (Paper I and II). Then we attempted to explore the potential of those chemistries in fabricating 3D hydrogel scaffolds for regenerative medicine application. A novel mild and regioselective method was devised to introduce an aldehyde moiety onto glycosaminoglycans structure. This involved the introduction of amino glycerol to glycosaminoglycans, followed by regioselective oxidation of tailed flexible diol without affecting the C2-C3 diol groups on the disaccharide repeating unit. The oxidation rate of the tailed flexible diol was 4-times faster than that of C2-C3 diol groups of native glycosaminoglycan. This strategy preserves the structural integrity of the glycosaminoglycans and provides a functional aldehyde moiety (Paper III). Further, different types of hydrazones were designed and their hydrolytic stability under acidic condition was carefully evaluated. The hydrazone linkage with the highest hydrolytic stability was utilized in the preparation of extracellular matrix hydrogel for delivery of bone morphogenetic proteins 2 in bone regeneration (Paper IV) and studied for controlled release of the growth factor (Paper III). In summary, this thesis presents a selection of strategies for designing bioconjugation chemistries that possess tunable stability and reaction kinetics under physiological conditions. These chemistries are powerful tools for conjugation of biomolecules for the biomedical applications.

Kolmaterial, såsom kolfibrer och kolskum, används som värmeisolatorer i applikationer vid höga temperaturer. För närvarande härleds dessa material från fossilbaserade källor, vilket tyder på ett behov av att hitta alternativa kandidater baserade på förnybara källor. Detta examensarbete undersökte möjligheten att använda kraftlignin som ett förnyelsebart startmaterial för framställning av kolskum med värmeisoleringsegenskaper. Två kraftligniner av barrträd med olika molekylvikter och ett kraftlignin av lövträd användes. De tre kraftligninerna karboniserades vid 1000°C efter att ha blandats i olika förhållanden och kombinationer (formuleringen av råmaterialet). Formuleringen av råmaterialet påverkade densiteten och porositeten hos de erhållna materialen, vilket i sin tur ledde till skillnader i kompressionsstyrkan och värmeledningsförmågan hos de erhållna kolskummen. Kolskummen hade olika värmeledningsförmåga (0,11-0,35 W/mK), porositet (80,55-97,53%) och densitet (0,08-0,42 g/cm3). För skummet med den högsta densiteten uppskattades krossstyrkan till cirka 10,03 MPa vilket är jämförbart med kommersiellt använda kolskum för högtemperaturisolerande applikationer. Kolskummens värmeledningsförmåga var inom omfånget för kommersiellt använda kolskum för högtemperaturapplikationer. Detta arbete visar möjligheten att tillverka kolskum från 100% kraftlignin som har liknande egenskaper som kommersiellt tillgängliga termiska isoleringsmaterial för högtemperaturapplikationer. / Carbon materials, such as carbon fibres and carbon foams, are used as thermal insulators in high-temperature applications. At present, these materials are derived from fossil-based sources, which suggests a need of finding alternatives candidates based on renewables. This thesis work investigated the possibility of using kraft lignin as a renewable starting material for the preparation of carbon foams with thermal insulation properties. Two softwood kraft lignins with different molecular weights and a hardwood kraft lignin were used. The three kraft lignins were carbonized at 1000°C after being mixed in different ratios and combinations (precursor formulation). The precursor formulation affected the density and porosity of the obtained materials, which in turn led to differences in compression strength and thermal conductivity of the carbon foams derived. The obtained carbon foams had different thermal conductivities (0.11-0.35 W/mK), porosity (80.55-97.53%) and density (0.08-0.42 g/cm3). For the foam with the highest density, the crushing strength was estimated to approximately 10.03 MPa which is comparable to commercially used carbon foams for high-temperature insulating applications. The thermal conductivity of the prepared carbon foams was in the range of commercially used carbon foams for high-temperature applications. This work demonstrates the possibility of preparing carbon foams from 100% kraft lignin which has properties similar of commercially available insulating materials for high-temperature applications.

Bioplastic research has become more diverse and different types of research on bioplastic production have been conducted from fruits and vegetable waste, for example, orange waste. The wastes that come from oranges contain more than just vitamins, it has soluble sugars, starch, hemicellulose, cellulose, and pectin. The intention of this project was to study the possibility to produce bio-composite films from orange waste, after removing the soluble sugars. It was also to analyze the properties of the material by tensile strength, visual observation, and to find a methodology that suits this study. An ultrafine grinder was used to mechanically separate the cellulose fibres, with the intention to compare the fibrillation cycles on the properties of the bio-composite films. A total of 30fibrillation cycle was performed. In addition, different film casting strategies were performed and evaluated. The primary plan was to produce a biofilm without the use of chemicals. After the observing the results three new routes for the methodology was developed where the usage of chemicals was be included. The citric acid was used as a solvent for pectin and glycerol was used as a plasticizer. In the first method, different concentration of citric acid and glycerol were added and observed. The combination which gave uniformed films that contained 0.3 g of citric and 0.375 g of glycerol for a 75 ml hydrogel. The second method was to infuse citric acid before grinding the orange waste suspension. Lastly, the third method was to bleach the orange waste before grinding. The films that were produced gave interesting results and from the tensile testing implied that an impact was made on the strength by every fibrillation. The amount of glycerol was consistent throughout the project, but by adding different amount of citric acid gave the films differentIIproperties. The same happened when changing the mould of the film. The best values of the films were from the 30th fibrillation, gave the mean value of 31.6 MPa in tensile strength, and had a strain in elongation at 6.1 %. The tensile strength and elongation had increased drastically compared the fifth fibrillation which had 9.8 MPa and 7.6%.

The present work was performed at Sherwin–Williams Sweden group AB with the objective of comparing short-wavelength light emitting diodes (UVB/UVC) with the conventional mercury arc lamp as a curing method of acrylate-based, UV-paint undergoing free-radical polymerization when exposed to UV-radiation. Due to environmental and health risks, mercury-doped radiation sources will be phased out in the near future, according to the United Nations Minamata convention, hence new alternatives are needed. Light-emitting diodes differ from the mercury arc lamp as they provide semi-discrete output intensity lines within the UV spectrum instead of a broad output distribution with several main intensity lines. The power output is also considerably lower compared to the conventional method which limits the irradiance and dose that are key parameters in activating and propagating free-radical polymerization of UV-paint. Seven different light-emitting diodes between 260–320 nm was examinedand compared to the conventional mercury arc lamp. Cured coatings were evaluated by measuring the relative extent of acrylate conversion with ATR-FTIR and micro-hardness indentation test. Both methods correlate to the relative cross-linking density and qualitatively describe the curing process for each radiant source at a specific irradiance and dose. Three different paint formulations with widely different properties were used in the experiments. All three paints were able to cure with one or several light emitting diodes at comparable doses and 10 to 20 times lower irradiance to the conventional mercury arc lamp, resulting in similar acrylate conversion and hardness.

A uniaxial High-Velocity Compaction (HVC) process for polymer powder using a cylindrical, hardened steel die and a new technique with relaxation assist was tested with a focus on the compactibility characteristics and surface morphology of the compacted materials using various heights of relaxation assist device with different compacting profiles. Relaxation assist device was presented as a new technique to reduce springback, pull-out phenomenon and to improve the compaction process. The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain pull-out phenomenon during the decompacting stage. In this study, polyamide-11 powders with different particle size distributions have been compacted with the application of different compaction profiles, e.g. different energies and velocities. It was found that the relative green density is influenced more by the pre-compacting (primary compaction step) than by the post-compacting (secondary compaction step). Experimental results for different compaction profiles were presented showing the effect of varying the opposite velocity during the decompacting stage and how to improve the homogeneous densification between the upper and lower surface and the evenness of the upper surface of the compacted powder bed by using relaxation assists, and the influences of the relaxation assist device on the process characteristics. It was found that the relaxation assist improves the compaction of the polymer powder by locking the powder bed in the compacted form. In addition, the relative times of the compacting stage, decompacting stage and the reorganisation of the particles can be controlled by altering the height of the relaxation assist. It was found that the high-velocity compaction process is an interruption process and that the delay times between the pressure waves can be reduced by increasing the height of the relaxation assist device. Furthermore, the first gross instantaneous springback and the total elastic springback are reduced. Two bonding strain gauges and a high-speed video camera system were used to investigate the springback phenomenon during the compaction process. Scanning electron microscopy (SEM) and image computer board Camera (IC-PCI Imaging Technology) were used to the study the morphological characteristics, the limit of plastic deformation and particle bonding by plastic flow at contact points, and pull-out phenomena. / QC 20100506