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| 3. |
- Pitois, Claire, et al.
(författare)
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Fluorinated dendritic polymers and dendrimers for waveguide applications
- 2003
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Ingår i: Optical materials (Amsterdam). - 0925-3467 .- 1873-1252. ; 21:1-3, s. 499-506
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Tidskriftsartikel (refereegranskat)abstract
- I Fluorinated hyperbranched polymers and dendrimers with low optical losses and functionality to modify refractive index and add a cross-linking unit were developed. The results of refractive index. measurements indicate a tunability of the refractive index between approximately 1.5 and 1.6, and optical losses below 0.5 dB/cm at 1550 nm. Dendrimers with similar, surface group structure and possibility to surface functionalization were prepared using a lanthanide. cation as focal point. Results on luminescent properties in the NIR and IR regions were measured for lanthanide ions such as Nd3+ and Er3+, showing characteristic emission bands at 1.06, 1.3 and 1.5 mum. The associated absorption and excitation spectra were found similar to those of the corresponding ions in optical glasses.
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| 4. |
- Ludvigsson, Mikael
(författare)
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Materials for future power sources
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Proton exchange membrane fuel cells and lithium polymer batteries are important as future power sources in electronic devices, vehicles and stationary applications. The development of these power sources involves finding and characterising materials that are well suited r the application.The materials investigated in this thesis are the perfluorosulphonic ionomer NafionTM (DuPont) and metal oxides incorporated into the membrane form of this material. The ionomer is used as polymer electrolyte in proton exchange membrane fuel cells (PEMFC) and the metal oxides are used as cathode materials in lithium polymer batters (LPB).Crystallinity in cast Nafion films can be introduced by ion beam exposure or aging. Spectroscopic investigations of the crystallinity of the ionomer indicate that the crystalline regions contain less water than amorphous regions and this could in part explain the drying out of the polymer electrolyte membrane in a PEMFC.Spectroscopic results on the equilibrated water uptake and the state of water in thin cast ionomer films indicate that there is a full proton transfer from the sulphonic acid group in the ionomer when there is one water molecule per sulphonate group.The LPB cathode materials, lithium manganese oxide and lithium cobalt oxide, were incorporated in situ in Nafion membranes. Other manganese oxides and cobalt oxides were incorporated in situ inside the membrane. Ion-exchange experiments from HcoO2 to LiCoO2 within the membrane were also successful.Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction were used for the characterisation of the incorporated species and the Nafion film/membrane.
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- Crispin, Xavier, et al.
(författare)
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Conductivity, Morphology, Interfacial Chemistry, and Stability of Poly(3,4- ethylene dioxythiophene)–Poly(styrene sulfonate) : A Photoelectron Spectroscopy Study
- 2003
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 41:21, s. 2561-2583
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Forskningsöversikt (refereegranskat)abstract
- X-ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDT/PSS), one of the most common electrically conducting organic polymers. A correlation has been established between the composition, morphology, and polymerization mechanism, on the one hand, and the electric conductivity of PEDT/PSS, on the other hand. XPS has been used to identify interfacial reactions occurring at the polymer-on-ITO and polymer-on-glass interfaces, as well as chemical changes within the polymer blend induced by electrical stress and exposure to ultraviolet light.
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| 6. |
- Claesson, Hans, et al.
(författare)
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Semi-crystalline thermoset resins : tailoring rheological properties in melt using comb structures with crystalline grafts
- 2004
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Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 49:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- Thermosetting resins with semi-crystalline grafts have been synthesized. An amorphous resin with epoxide groups was first functionalized with hydroxyl groups using 2,2-bis(methylol) propionic acid, bis-MPA in bulk at 155 degreesC. Functionalization with bis-MPA was monitored using FT-IR, FT-Raman and SEC. The reaction was complete in 30 min. Grafts of poly(epsilon-caprolactone) were then grown from the hydroxyl functional resin and end capped with methacrylate groups. The polymerization Of epsilon-caprolactone, performed in bulk at 110 degreesC using Sn(Oct)(2), was characterized using H-1 NMR and SEC. The obtained molecular weights agreed well with theoretical values. The final end capping was performed using methacrylic anhydride, and monitored with SEC and H-1 NMR, which indicated full substitution. Two combs were synthesized with different arm lengths, DP 10 and 20, and the obtained M-W were close to calculated values. The complex viscosity was measured from low to high temperature for the crystalline resins, the amorphous resin and blends thereof. Rheological data show a rapid decrease in viscosity within a temperature change of 10-15 degreesC for the crystalline resins while the amorphous resin exhibited a slow softening. The blends exhibited a behavior in-between that of the crystalline and the amorphous resin. Films were prepared from the pure resins and the blends. The films were cured using UV irradiation. The comb architecture of these resins has advantages such as crystallinity, high molecular weight and low viscosity, facilitating leveling and resulting in smooth films. The final film properties varied with the ratio of crystalline to amorphous resin, where increase in the amount of crystalline resin correlated with increased the flexibility.
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| 8. |
- Gavelin, Patrick
(creator_code:cre_t)
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Polymer gel electrolyte
- 2002
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- A polymer gel electrolyte comprising a metal salt, a polymer, optionally a plasticizer, characterized in that the polymer comprises a carbon-hydrogen base chain having at least two reactive groups incorporated wherein the reactive groups have different reactivities. The polymer gel electrolyte neutralises a passivating layer in the form of waste products produced in the electrolyte phase by the metal salt and solvents. The decrease in the growth of the passivating layer provides a battery cell with a better effect and a longer life.
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| 9. |
- Gröning, Mikael, 1973-
(författare)
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Solid-Phase Microextraction in Polymer Analysis - Extraction of Volatiles from Virgin and Recycled Polyamide 6.6
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The extraction and quantitative analysis of low molar mass compounds in polymers is an analytical challenge. It is also important from a practical point of view because the low molar mass compounds in time will migrate from the polymers into the surrounding environment. It is especially important to gain knowledge about the migrating compounds in applications such as medical implants, packaging materials and car interiors. The main aim of this thesis was to develop headspace solid phase microextraction (HS-SPME) methods to meet this challenge. In addition, the work aimed to show the applicability of the methods developed in quality control of polymers, degradation studies and assessment of polymer durability. Factors influencing the extraction of low molar mass compounds from polyamide 6.6 were studied. Particular attention was paid to the matrix effects and to the establishment of headspace equilibrium of 2-cyclopentyl-cyclopentanone in solid polyamide. Hydrogen bonding and adsorption of analyte to the polar matrix was observed and found to cause exceedingly slow establishment of equilibrium. The adsorption could be eliminated by the addition of water, which replaced 2-cyclopentyl-cyclopentanone at the adsorption sites of the polyamide and made it possible to measure the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using multiple headspace solid-phase microextraction (MHS-SPME). A correlation between the emitted amount of 2-cyclopentyl-cyclopentanone and the amount 2-cyclopentyl-cyclopentanone in the material was found. The correlation was valid also under non-equilibrium conditions, which allows rapid assessment of the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using headspace sampling. 20 different low molar mass compounds were identified in virgin and recycled polyamide 6.6. The compounds could be classified into four groups: cyclic imides, pyridines, chain fragments and cyclopentanones. The structures of the degradation products imply that the thermo-oxidative degradation starts at the N-vicinal methyl group. Larger amounts of degradation products at lower degree of degradation were formed in recycled than in virgin polyamide 6.6. Thus, processing increases the susceptibility of polyamide 6.6 to thermal oxidation. The total amount of cyclopentanones was reduced upon processing and oxidation. Cyclopentanones are thus not thermo-oxidation products of polyamide 6.6. N-pentyl-succinimide showed the most significant increase due to oxidation and processing. The formation of N-pentyl-succinimide was in correlation with the simultaneous changes in tensile strength. The largest increase in N-pentyl-succinimide coincided with the largest drop in tensile strength.
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| 10. |
- Jannasch, Patric
(creator_code:cre_t)
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A binder and/or electrolyte material
- 2001
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- A binder and/or electrolyte material and method for production thereof, which material is intended to be used in the preparation of a porous electrode (5) for a cell (100), wherein the binder and/or electrolyte material (20) comprises an ion conducting polymer (10).
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