Finn Knut Hansen

• Levchenko, Vladimir; Sundsli, Bård Edgar Vestheim; Øien-Ødegaard, Sigurd; Tilset, Mats; Hansen, Finn Knut & Hansen, Tore Bonge (2018). Bottom-Up Synthesis of Acrylic and Styrylic Rh11 Carboxylate Polymer Beads: Solid-Supported Analogs Rh2(OAc)4. European Journal of Organic Chemistry. ISSN 1434-193X. p. 6150–6157. doi: 10.1002/ejoc.201800953. Full text in Research Archive
• Scheie, Anne Aamdal; Chamgordani, Elahe Jafari; Naemi, Ali-Oddin; Hansen, Finn Knut & Benneche, Tore (2016). Staphylococcus epidermidis biofilm on implant material is reduced by a covalently linked thiophenone. Journal of Applied Microbiology. ISSN 1364-5072. 121(2), p. 547–553. doi: 10.1111/jam.13188. Full text in Research Archive
• Moxnes, John Fredrik; Hansen, Finn Knut; Jensen, Tomas Lunde; Sele, Marta Lill & Unneberg, Erik (2016). A computational study of density of some high energy molecules. Propellants, explosives, pyrotechnics. ISSN 0721-3115. doi: 10.1002/prep.201600105. Full text in Research Archive Show summary

  The detonation pressure depends quadratically on the loading density of the explosives. A precise estimate of the density is thus crucial to decide if a novel energetic material is worth pursuing. In this work we investigate theoretically the crystal densities of the energetic compounds RDX, TNT, NTO, DNAM, CL-20, DADNE, and HMX. We calculate the crystal densities by using Materials Studio 7.0 Polymorph Predictor, employing force fields and exploring molecular packing arrangements with minima in total energy. Geometry optimized molecular structures computed by density functional theory (DFT) are used as input to the density predictions. In an additional DFT study we apply two functionals, B3LYP and M06 with the 6-31G(d) and the 6-31G(d,p) basis sets, and the program package GAUSSIAN09. In this part of the work crystal densities are calculated by using the molecular isosurface volume (defined by the volume within a surface with an electron density of 0.001 electrons per Bohr3) alone or combined with the variance of the electrostatic potential (ESP). The Polymorph Predictor seems to overestimate the densities, but the values are very dependent on the force field strength determined by charges assigned to atoms. In the GAUSSIAN09 DFT study the densities derived by using the M06 functional are in similar agreement with experimental data as what we experienced for the B3LYP results, although both functionals appear to give slightly lower densities than reported experimentally for the majority of the molecules. On average, the densities derived by the ESP method correlate equally well with measured values as the results obtained by the isosurface method.

• Frømyr, Tomas Roll; Bourgeaux-Goget, Marie & Hansen, Finn Knut (2015). A comparative study of the dispersion of multi-wall carbon nanotubes made by arc-discharge and chemical vapour deposition. Journal of Nanoscience and Nanotechnology. ISSN 1533-4880. 15(5), p. 3496–3506. doi: 10.1166/jnn.2015.9860. Full text in Research Archive
• Christensen, Mikkel; Larnøy, Erik; Kutzke, Hartmut & Hansen, Finn Knut (2015). Treatment of waterlogged archaeological wood using chitosan and modified chitosan solutions. Part 1: Chemical compatibility and microstructure. Journal of the American Institute for Conservation. ISSN 0197-1360. 54(1), p. 3–13. doi: 10.1179/1945233014Y.0000000034. Full text in Research Archive
• Lausund, Kristian Blindheim; Johnsen, Bernt Brønmo; Rahbek, Dennis Bo & Hansen, Finn Knut (2015). Surface treatment of alumina ceramic for improved adhesion to a glass fibre-reinforced polyester composite. International Journal of Adhesion and Adhesives. ISSN 0143-7496. doi: 10.1016/j.ijadhadh.2015.07.015. Full text in Research Archive Show summary

  The adhesion between an alumina ceramic and a glass fibre-reinforced polyester matrix composite has been investigated. The effect of various alumina surface treatments, including degreasing, etching, plasma, grit-blasting and silanisation, was evaluated. The physical and chemical surface properties were investigated by microscopy, profilometry, contact angle measurements and X-ray photoelectron spectroscopy. The analysis showed that the treatments removed organic contaminants from the alumina, resulting in higher surface free energies. Alumina/composite test specimens were prepared by a vacuum moulding technique, and the adhesive strength was evaluated using the fixed arm peel test. All surface treatments had a pronounced effect on the peel strength, and the adhesion was improved compared to the as-received alumina. This was verified by investigation of the fracture surfaces. The silane treatment produced a thin silane layer on the surface and had the greatest effect on the adhesive strength. This could be explained by the silane acting as an adhesion promoter between the alumina and the composite, better wetting of the more planar silane treated surface by the thermoplastic polyester, and a more defect-free alumina/polyester interphase.

• Thorvaldsen, Tom; Johnsen, Bernt Brønmo; Olsen, Torbjørn & Hansen, Finn Knut (2015). Investigation of Theoretical Models for the Elastic Stiffness of Nanoparticle-Modified Polymer Composites. Journal of Nanomaterials. ISSN 1687-4110. doi: 10.1155/2015/281308. Full text in Research Archive Show summary

  Mathematical models are investigated and suggested for the calculation of the elastic stiffness of polymer nanocomposites. Particular emphasis is placed on the effect on the elastic stiffness from agglomerates and the particle interphase properties. The multiphase Mori-Tanaka model and an interphase model are considered as two relevant models. These models only include and require the designation of a few system independent parameters with a clear physical meaning. Extensions of the models are also presented. The model calculations are compared to results from other models, as well as experimental data for different nanocomposites. For nanocomposites with spherical particles and with fiber-like particles, the suggested models are found to be the most flexible ones and are applicable to estimate the stiffness increase of nanocomposites for both low and high particle volume fractions. The suggested theoretical models can hence be considered as a general multiscale “model toolbox” for analysis of various nanocomposites.

• Christensen, Mikkel; Kutzke, Hartmut & Hansen, Finn Knut (2014). Phenol formaldehyde revisited – novolac resins for the treatment of degraded archaeological wood. Archaeometry. ISSN 0003-813X. doi: 10.1111/arcm.12097. Full text in Research Archive Show summary

  Archaeological wood is usually severely degraded. The Norwegian Viking Age Oseberg find exemplifies problems arising due to past conservation treatments and the need for new types of preservatives. Phenol formaldehyde (PF) has been investigated as a consolidant for alum-treated wood. X-ray tomography has revealed that it is possible to obtain a porous structure inside the wood, ensuring ethical acceptability by allowing re-treatment. In order to understand the curing mechanics, the kinetics of the initial condensation reaction were elucidated at room temperature. It was found that a second-order reaction using both phenol and formaldehyde concentrations is the most probable mechanism.

• Landsem, Eva; Jensen, Tomas Lunde; Kristensen, Tor Erik Holt; Hansen, Finn Knut; Benneche, Tore & Unneberg, Erik (2013). Isocyanate-Free and Dual Curing of Smokeless Composite Rocket Propellants. Propellants, explosives, pyrotechnics. ISSN 0721-3115. doi: 10.1002/prep.201200108. Full text in Research Archive Show summary

  Traditional composite rocket propellants are cured by treatment of hydroxyl-terminated prepolymers with polyfunctional aliphatic isocyanates. For development of smokeless composite propellants containing nitramines and/or ammonium dinitramide (ADN), energetic binder systems using glycidyl azide polymer (GAP) are of particular interest. Polyfunctional alkynes are potential isocyanate-free curing agents for GAP through thermal azide-alkyne cycloaddition and subsequent formation of triazole crosslinkages. Propargyl succinate or closely related aliphatic derivatives have previously been reported for such isocyanate-free curing of GAP. Herein, we present the synthesis and use of a new aromatic alkyne curing agent, the crystalline solid bisphenol A bis(propargyl ether) (BABE), as isocyanate-free curing agent in smokeless propellants based on GAP, using either octogen (HMX) and/or prilled ADN as energetic filler materials. Thermal and mechanical properties, impact and friction sensitivity and ballistic characteristics were evaluated for these alkyne cured propellants. Improved mechanical properties could be obtained by combining isocyanate and alkyne curing agents (dual curing), a combination that imparted better mechanical properties in the cured propellants than either curing system did individually. The addition of a neutral polymeric bonding agent (NPBA) for improvement of binder-filler interactions was also investigated using tensile testing and dynamic mechanical analysis (DMA). It was verified that the presence of isocyanates is essential for the NPBA to improve the mechanical properties of the propellants, further strengthening the attractiveness of dual cure systems.

• Christensen, Mikkel; Kutzke, Hartmut & Hansen, Finn Knut (2012). New materials used for the consolidation of archaeological wood – past attempts, present struggles, and future requirements. Journal of Cultural Heritage. ISSN 1296-2074. 13(3), p. S183–S190. doi: 10.1016/j.culher.2012.02.013. Full text in Research Archive
• Landsem, Eva; Jensen, Tomas Lunde; Hansen, Finn Knut; Kristensen, Tor Erik Holt & Unneberg, Erik (2012). Mechanical Properties of Smokeless Composite Rocket Propellants Based on Prilled Ammonium Dinitramide. Propellants, explosives, pyrotechnics. ISSN 0721-3115. doi: 10.1002/prep.201200004. Full text in Research Archive Show summary

  Ammonium dinitramide (ADN) is a high performance solid oxidizer of interest for use in high impulse and smokeless composite rocket propellant formulations. While rocket propellants based on ADN may be both efficient, clean burning, and environmentally benign, ADN suffers from several notable disadvantages such as pronounced hygroscopicity, significant impact and friction sensitivity, moderate thermal instability, and numerous compatibility issues. Prilled ADN is now a commercially available and convenient product that addresses some of these disadvantages by lowering the specific surface area and thereby improving handling, processing, and stability. In this work, we report the preparation, friction and impact sensitivity and mechanical properties of several smokeless propellant formulations based on prilled ADN and isocyanate cured and plasticized glycidyl azide polymer (GAP) or polycaprolactone-polyether. We found such propellants to have very poor mechanical properties in unmodified form and to display somewhat unreliable curing. However, by incorporation of octogen (HMX) and a neutral polymeric bonding agent (NPBA), the mechanical properties of such smokeless formulations were significantly improved. Impact and friction sensitivities of these propellants compare satisfactorily with conventional propellants based on ammonium perchlorate (AP) and inert binder systems.

• Landsem, Eva; Jensen, Tomas Lunde; Hansen, Finn Knut; Unneberg, Erik & Kristensen, Tor Erik Holt (2012). Neutral Polymeric Bonding Agents (NPBA) and Their Use in Smokeless Composite Rocket Propellants Based on HMXGAP- BuNENA. Propellants, explosives, pyrotechnics. ISSN 0721-3115. doi: 10.1002/prep.201100136. Full text in Research Archive Show summary

  Very few efficient bonding agents for use in solid rocket propellants with nitramine filler materials and energetic binder systems are currently available. In this work, we report the synthesis, detailed characterization, and use of neutral polymeric bonding agents (NPBA) in isocyanate-cured and smokeless composite rocket propellants based on the nitramine octogen (HMX), the energetic binder glycidyl azide polymer (GAP), and the energetic plasticizer N-butyl-2-nitratoethylnitramine (BuNENA). These polymeric bonding agents clearly influenced the viscosity of the uncured propellant mixtures and provided significantly enhanced mechanical properties to the cured propellants, even at low NPBA concentrations (down to 0.001 wt-% of propellant). A modified NPBA more or less free of hydroxyl functionalities for interactions with isocyanate curing agent provided the same level of mechanical improvement as regular NPBA containing a substantial number of reactive hydroxyl groups. However, some degree of reactivity towards isocyanate is essential for function.

• Frømyr, Tomas Roll; Hansen, Finn Knut & Olsen, Torbjørn (2012). The Optimum Dispersion of Carbon Nanotubes for Epoxy Nanocomposites: Evolution of the Particle Size Distribution by Ultrasonic Treatment. Journal of Nanotechnology. ISSN 1687-9503. doi: 10.1155/2012/545930. Full text in Research Archive Show summary

  The ultrasonic dispersion of multiwalled carbon nanotube (MWCNT) suspensions was assessed by studying the differential sedimentation of the particles in an acid anhydride often employed as a curing agent for epoxy resins. The particle size distributions were characterized by the means of a disc centrifuge, and the effect of dispersion time, power density, and total energy input, for both bath and circulation probe ultrasonic dispersing equipment was investigated. The mass of freely suspended MWCNTs relative to agglomerated MWCNTs was estimated as a measure of the quality of the dispersions, and the results showed that this ratio followed a power law scaling with the energy dissipated in the sonication treatment. If the sonication power level was too high, sonochemical degradation of the curing agent could occur. The mean agglomerate MWCNT size distribution was estimated, and the fragmentation of the agglomerates was modeled by means of fragmentation theory. Indications of both rupture and erosion fragmentation processes for the MWCNT agglomerates were observed.

• Truong, Thuy le; Larsen, Åge Gellein; Holme, Børge; Hansen, Finn Knut & Roots, Jaan (2011). Morphology of syndiotactic polypropylene/alumina nanocomposites. Polymer. ISSN 0032-3861. 52(4), p. 1116–1123. doi: 10.1016/j.polymer.2011.01.014. Full text in Research Archive Show summary

  The effect of the addition of 50 nm spherical alumina nanoparticles with hydrophilic or hydrophobic surfaces on the morphology of syndiotactic polypropylene (sPP) was investigated. The filler content in the nanocomposites was 3 wt%. Polarized Optical Microscopy and Small Angle Light Scattering (SALS) studies showed that sPP and the nanocomposites form hedrites. The addition of alumina nanoparticles significantly increased the number of hedrites. A higher number of nucleation sites in the nanocomposites promote a higher crystallization rate, and thus hedritic growth was stopped at the early stage of crystallization. Quantitative evaluations by SALS analysis show that the object size is decreased by not only the crystallization conditions but also the presence of Al2O3 nanoparticles. A small amount of Al2O3 nanoparticles did not noticeably affect the crystallinity of sPP, but increased the melting point. Transmission Electron Microscopy images showed that the lamellar thickness did not change significantly with the incorporation of nanoparticles. The lamella thickness, however, depends on cooling rates. X-ray diffraction characterization indicated that the sPP and the nanocomposites were crystallized in disordered “form I”. The incorporation of alumina nanoparticles had a small effect on the crystal structure of syndiotactic polypropylene.

• Truong, Thuy le; Larsen, Åge; Holme, Børge; Diplas, Spyridon; Hansen, Finn Knut & Roots, Jaan [Show all 7 contributors for this article] (2010). Dispersibility of silane-functionalized alumina nanoparticles in syndiotactic polypropylene. Surface and Interface Analysis. ISSN 0142-2421. 42(6-7), p. 1046–1049. doi: 10.1002/sia.3166. Full text in Research Archive
• Kristensen, Tor Erik Holt; Vestli, Kristian; Jakobsen, Martin Gjerde; Hansen, Finn Knut & Hansen, Tore (2010). General Approach for Preparation of Polymer-Supported Chiral Organocatalysts via Acrylic Copolymerization. Journal of Organic Chemistry. ISSN 0022-3263. 75(5), p. 1620–1629. doi: 10.1021/jo902585j. Full text in Research Archive
• Kristensen, Tor Erik Holt; Vestli, Kristian; Hansen, Finn Knut & Hansen, Tore (2009). New Phenylglycine-Derived Primary Amine Organocatalysts for the Preparation of Optically Active Warfarin. European Journal of Organic Chemistry. ISSN 1434-193X. p. 5185–5191. doi: 10.1002/ejoc.200900664. Full text in Research Archive
• Kristensen, Tor Erik Holt; Vestli, Kristian; Fredriksen, Kim A; Hansen, Finn Knut & Hansen, Tore (2009). Synthesis of Acrylic Polymer Beads for Solid-Supported Proline-Derived Organocatalysts. Organic Letters. ISSN 1523-7060. 11(14), p. 2968–2971. doi: 10.1021/ol901134v. Full text in Research Archive
• Kristensen, Tor Erik Holt; Hansen, Finn Knut & Hansen, Tore (2009). The Selective O-Acylation of Hydroxyproline as a Convenient Method for the Large-Scale Preparation of Novel Proline Polymers and Amphiphiles. European Journal of Organic Chemistry. ISSN 1434-193X. p. 387–395. doi: 10.1002/ejoc.200800941. Full text in Research Archive
• Hansen, Finn Knut (2008). Surface dilatational elasticity of poly(oxy ethylene)-based Surfactants by oscillation and relaxation measurements of sessile bubbles. Langmuir. ISSN 0743-7463. 24(1), p. 189–197. doi: 10.1021/la7024582. Full text in Research Archive Show summary

  Surface dilatational elasticities and viscosities have been measured by means of the axisymmetric bubble shape method. Two different techniques using sinusoidal oscillations and step relaxations have been used, and the results are treated by means of the bulk/surface diffusional exchange model. Three different nonionic surfactants based on poly(oxy ethylene) as the hydrophilic group have been used: one simple surfactant, Brij 35, and two block copolymers, Pluronic F68 and P9400. Step relaxation and oscillation give mostly the same limiting surface dilatational elasticities, but step relaxation is a more model-dependent method. In the cases where the bulk/surface diffusion model is correct, the two methods give the same results, but otherwise step relaxation gives average values of the limiting elasticity E0 and the typical relaxation frequency 0. Limiting elasticities up to ca. 25 mN m-1 have been found for these substances. The surface/bulk diffusion model describes quite well the two relatively hydrophilic substances Brij 35 and F68, especially at low concentrations, but less so for the more hydrophobic P9400. The surface dilatational elasticity as a function of the surface pressure of the surface-active polymers goes through at least one maximum as a result of surface conformational changes.

• Grythe, Kai Frode & Hansen, Finn Knut (2007). Diffusion Rates and the Role of Diffusion in Solid Propellant Rocket Motor Adhesion. Journal of Applied Polymer Science. ISSN 0021-8995. 103(3), p. 1529–1538. doi: 10.1002/app.25086. Full text in Research Archive Show summary

  Diffusion rates can give important information for the adhesion process across the bondline between insulation and propellant in solid propellant rocket motors. Diffusion coefficients of low molecular weight species such as crosslinkers and plasticizers have been measured by the weight of uptake method in polymer materials that are candidates for propellant contact. The materials were EPDM insulation sheets and ‘‘liners,’’ based on HTPB, HTPE, or GAP, and with different degrees of particle filling. Plots of relative mass gain as a function of the square root of time showed good linearity up to 20 50% weight increase and the diffusion coefficients could thus be determined with good accuracy. The diffusion coefficients for the low molecular weight isocyanates and plasticizers in these materials vary between 10 11 and 10 17 m2 s1, dependent on material types and particle filling. In most cases, the results can be explained by the solubility parameters of the organic liquids and polymers. For the particle filled samples, the diffusion coefficients decrease with increasing degree of particle filling, and the decrease if faster than predicted by the Maxwell Fricke or the Keller models for arrays of smooth spheres.

• Grythe, Kai Frode; Hansen, Finn Knut & Olsen, Torbjørn (2007). Adhesion in Solid Propellant Rocket Motors. The journal of adhesion. ISSN 0021-8464. 83(3), p. 223–254. doi: 10.1080/00218460701239059. Full text in Research Archive Show summary

  Plasma treatment of EPDM based rocket motor insulation materials may change the peel strength between these materials and polyurethane polymers with a factor of 0.5 to 10. The matching of surface energies seems to be important for this adhesion process. The surface tension of the components was measured to between ca 30 and 50 mNm-1. The total surface energy of the insulation could be increased from 27.2 mNm-1 to ca 70 mNm-1 by the plasma process. Maximum peel strength could be obtained by less than one minute treatment, while longer times in most cases gave lower values. In some cases very long treatment also gave good strength, probably due to a rougher surface structure. The rate of cure of the polymer was important for the adhesion process as longer curing time correlated with higher peel strengths, which can be explained by diffusion of the polymer’s components into the insulation.

• Grythe, Kai Frode & Hansen, Finn Knut (2006). Surface modification of EPDM rubber by plasma treatment. Langmuir. ISSN 0743-7463. 22(14), p. 6109–6124. Full text in Research Archive Show summary

  The effect of argon, oxygen, and nitrogen plasma treatment of solvent cast EPDM rubber films has been investigated by means of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and surface energy measurements. Plasma treatment leads to changes in the surface energy from 25 to 70 mN/m. Treatment conditions influenced both the changes in surface energy and the stability, and it became more difficult to obtain good contact angle measurements after longer (> ca. 4 min) treatment times, probably because of an increasingly uneven surface structure. XPS analyses revealed that up to 20 at. % oxygen can be easily incorporated and that variations of /-%5 can be controlled by the plasma conditions. Oxygen was mainly found in hydroxyl groups, but also as carbonyl and carboxyl. XPS analyses showed more stable surfaces than expected from contact angles, probably because XPS analysis is less surface sensitive than contact angle measurements. AFM measurements revealed different surface structures with the three gases. The surface roughness increased generally with treatment time, and dramatic changes could be observed at longer times. At short times, surface energy changes were much faster than the changes in surface structure, showing that plasma treatment conditions can be utilized to tailor both surface energies and surface structure of EPDM rubber.

• Hansen, Finn Knut (2005). Historic Overview. In Herk, Alex Van (Eds.), Chemistry and Technology of Emulsion Polymerisation. Blackwell Publishing. ISSN 9781405121132. p. 3–24. Full text in Research Archive
• Davis, J.; Foegeding, E.A. & Hansen, Finn Knut (2004). Electrostatic effects on the yield stress of whey protein isolate foams. Colloids and Surfaces B: Biointerfaces. ISSN 0927-7765. 34, p. 13–23. Full text in Research Archive
• Grythe, Kai Frode; Hansen, Finn Knut & Walderhaug, Harald (2004). NMR self-diffusion and viscosity of polyurethane formulations for rocket propellants. Journal of Physical Chemistry B. ISSN 1520-6106. 108, p. 12404–12412. Full text in Research Archive
• Frømyr, T.; Hansen, Finn Knut; Kotzev, A. & Laschewsky, A. (2001). Adsorption and surface elastic properties of corresponding fluorinated and non-fluorinated cationic polymer films measured by drop shape analyis. Langmuir. ISSN 0743-7463. 17, p. 5256–5254. Full text in Research Archive
• Hansen, Finn Knut & Kopperud, Hilde Beate Molvig (2001). Surface tension and surface dilatational elasticity of associating hydrophobically modified polyacrylamides in aqueous solutions. Macromolecules. ISSN 0024-9297. 34, p. 5635–5643. Full text in Research Archive
• Myrvold, Rolf; Hansen, Finn Knut & Lindman, Björn (2000). The Adsorption and Surface Dilatational Rheology of Unmodified and Hydrophobically Modified EHEC, Measured by Means of Axisymmetric Drop Shape Analysis. ACS Symposium Series. Full text in Research Archive
• Myrvold, Rolf; Hansen, Finn Knut; Balinov, Balin & Skurtveit, Roald (1999). Monolayers of Some Poly(oxyethylene)-Based Surfactants at the Air-Water Interface: The Effect of Structural Variations and Salt Concentration. Journal of Colloid and Interface Science. ISSN 0021-9797. 215, p. 409–419. Full text in Research Archive
• Hansen, Finn Knut & Hveem, J. (1999). The Interfacial Tension between Acrylic Monomers and Polymers and Non-ionic Surfactants Investigated by the Automatic Sessile Drop. Journal of Colloid and Interface Science. ISSN 0021-9797. 210, p. 144–151. Full text in Research Archive
• Kopperud, Hilde Beate Molvig; Walderhaug, Harald & Hansen, Finn Knut (1999). Polymer self-diffusion and surfactant bindig in aqueous solutions of unmodified and hydrophobocally modofied polyacrylamide studied by pulsed field gradient NMR and surface tension measurements. Macromolecular Chemistry and Physics. ISSN 1022-1352. 200, p. 1839–1845. Full text in Research Archive
• Myrvold, Rolf & Hansen, Finn Knut (1998). Surface Elasticity and Viscosity From Oscillating Bubbles Measured by Automatic Axisymmetric Drop Shape Analysis. Journal of Colloid and Interface Science. ISSN 0021-9797. 207, p. 97–105. Full text in Research Archive
• Kopperud, Hilde Beate Molvig; Hansen, Finn Knut & Nyström, Bo (1998). Effect of surfactant and temperature on the rheological properties of aqueous solutions of unmodified and hydrophobically modified polyacrylamide. Macromolecular Chemistry and Physics. ISSN 1022-1352. 199(11), p. 2385–2394. Full text in Research Archive Show summary

  Linear and nonlinear viscoelasticity of semidilute aqueous solutions of an unmodified reference poly(acrylamide) (PAM) and of a hydrophobically modified poly(acrylamide) (HM-PAM) in the presence of various amounts of sodium dodecyl sulfate (SDS) and at different temperatures have been examined. Oscillatory shear experiments in the linear viscoelastic domain revealed significant polymer-surfactant interaction for the HM-PAM-SDS system at a surfactant concentration of ca. 8 mmolal, whereas practically no surfactant effect was observed for the PAM-SDS system. The rheological features for the HM-PAM-SDS system were found to be strongly dependent upon the level of surfactant addition, with first an increase and then a decrease in the values of parameters such as the dynamic viscosity. While the position of the maximum of the viscosity curve, with regard to the surfactant concentration, was independent of polymer concentration and temperature, the strength of the network was promoted by increasing polymer content and decreasing temperature. At higher surfactant concentrations, a breakdown of chain associations occurred. A non-Newtonian shear thinning behavior, as well as a thixotropy, was detected for HM-PAM solutions in the presence of surfactant. These effects were most pronounced at ca. 8 mmolal SDS at the lowest temperature. The rheological features reveal that the hydrophobic associations, induced by HM-PAM-SDS interactions, play an important role for the viscoelastic properties of the system.

• Hansen, Finn Knut & Fagerheim, Hege (1997). The Influence of Oil Phase on the Adsorption of Non-ionic Surfactants Investigated by the Automatic Sessile Drop Method. Colloids and Surfaces A: Physicochemical and Engineering Aspects. ISSN 0927-7757. 137, p. 217–230. Full text in Research Archive
• Aabakken, Lars; Rosseland, Arne Retvedt; Osnes, Magne; Wara, Pål & Hansen, Finn Knut (1997). Utstyr, sikkerhet og dokumentasjon. In Aabakken, Lars; Osnes, Magne & Rosseland, Arne Retvedt (Ed.), Gastrointestinal endoscopi (The SADE book). Scandinavian Association of Digestive Endoscopy, Oslo. ISSN 9788299429801. p. 1–28. Full text in Research Archive
• Walderhaug, Harald; Nyström, Bo; Hansen, Finn Knut & Lindman, Björn (1995). Interactions of Ionic Surfactants with a Nonionic Cellulose Ether in Solution and in the Gel State Studied by Pulsed Field Gradient NMR. Journal of Physical Chemistry. ISSN 0022-3654. 99, p. 4672–4672. Full text in Research Archive
• Nyström, Bo; Walderhaug, Harald; Hansen, Finn Knut & Lindman, Björn (1995). Rheological Behavior During Thermoreversible Gelation of Aqueous Mixtures of Ethyl(hydroxyethyl) cellulose and Surfactants. Langmuir. ISSN 0743-7463. 11, p. 750–750. Full text in Research Archive
• Hansen, Finn Knut; Nyström, Bo & Walderhaug, Harald (1995). Dynamic Interactions and Adsorption in Systems of Hydrophobically Modified Water-soluble Polymers. Macromolecular Symposia (1986-1993). ISSN 0258-0322. 92, p. 345–345. Full text in Research Archive
• Walderhaug, Harald; Nyström, Bo; Hansen, Finn Knut & Lindman, Björn (1995). Surfactant-polymer interaction in thermo-induced gelling systems of ethyl(hydroxyethyl) cellulose (EHEC) studied by NMR self-diffusion, dynamic light scattering and rheology. Progress in Colloid and Polymer Science. ISSN 0340-255X. 98, p. 51–51. Full text in Research Archive
• Nyström, Bo; Walderhaug, Harald & Hansen, Finn Knut (1995). Dynamic Light Scattering and Rheological Studies of Thermoreversible Gelation of a Poly(ethylene oxide)-Poly(propyleneoxide)-Poly(ethyleneoxide) Triblock Copolymer in Aqueous Solution. Faraday discussions. ISSN 1359-6640. 101, p. 335–335. Full text in Research Archive
• Hansen, Finn Knut & Myrvold, Rolf (1995). The Kinetics of Albumin Adsorption to the Air/Water Interface Measured by Automatic Axisymmetric Drop Shape Analysis. Journal of Colloid and Interface Science. ISSN 0021-9797. 177, p. 408–408. Full text in Research Archive
• Walderhaug, Harald; Hansen, Finn Knut; Abrahmsen, Susanna; Persson, Karin & Stilbs, Peter (1993). Associative Thickeners. NMR Self-diffusion and Rheology Studies of Aqueous Solutions of Hydrophobically Modified Poly(oxyethylene) Polymers. Journal of Physical Chemistry. ISSN 0022-3654. 97, p. 8336–8336. Full text in Research Archive
• Nyström, Bo; Walderhaug, Harald & Hansen, Finn Knut (1993). Dynamic Crossover Effects Observed in Solutions of a Hydrophobically Associating Water-soluble Polymer. Journal of Physical Chemistry. ISSN 0022-3654. 97, p. 7743–7743. Full text in Research Archive
• Hansen, Finn Knut (1993). Surface Tension by Image Analysis. Fast and Automatic Measurements of Pendant and Sessile Drops and Bubbles. Journal of Colloid and Interface Science. ISSN 0021-9797. 160, p. 209–217. Full text in Research Archive
• Persson, Karin; Abrahmsen, Susanna; Stilbs, Peter; Walderhaug, Harald & Hansen, Finn Knut (1992). The association of urethane-polyethyleneoxide (HEUR) thickeners, as studied by NMR self-diffusion measurements. Colloid and Polymer Science. ISSN 0303-402X. 270, p. 465–465. Full text in Research Archive

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• Thorvaldsen, Tom; Johnsen, Bernt Brønmo; Olsen, Torbjørn & Hansen, Finn Knut (2016). Theoretical modelling of the elastic modulus of polymer nanocomposites. Full text in Research Archive
• Moxnes, John F.; Jensen, Tomas Lunde; Kjønstad, Eirik F.; Unneberg, Erik; Hansen, Finn Knut & Ødegårdstuen, Gard (2015). Detonation performance of high energy compounds determined by quantum mechanics. Full text in Research Archive Show summary

  Density, impact sensitivity and detonation performance for new explosives are calculated by QM. Use of isosurface volume or electrostatic potential is a good alternative for the Polymorph predictor. The B3LYP and M06-2X functionals, both with the 6-31G(d) basis set, show significantly different bond dissociation energies in the nitrimino functional group.

• Johnsen, Bernt Brønmo; Lausund, Kristian Blindheim; Rahbek, Dennis Bo & Hansen, Finn Knut (2015). Adhesion between alumina ceramic and glass fibre-reinforced polyester composite in hybrid armour systems. Full text in Research Archive
• Hansen, Finn Knut & Hansen, Tore (2012). Polymer particles with organocatalytic functionality. Abstract of Papers of the American Chemical Society. ISSN 0065-7727. 244. Full text in Research Archive
• Landsem, Eva; Jensen, Tomas Lunde; Kristensen, Tor Erik; Unneberg, Erik; Benneche, Tore & Hansen, Finn Knut (2012). Improving the properties of minimum smoke composite rocket propellants. Full text in Research Archive
• Landsem, Eva; Jensen, Tomas Lunde; Kristensen, Tor Erik; Unneberg, Erik & Hansen, Finn Knut (2012). Achieving Good Mechanical Properties in Smokeless Propellant Formulations Based on HMX-GAP-BUNENA with Polymeric Bonding Agents. Full text in Research Archive
• Christensen, Mikkel; Kutzke, Hartmut & Hansen, Finn Knut (2011). Biomimetic conservation: Cellulose and chitosan for wood preservation. Full text in Research Archive
• Kutzke, Hartmut; Braovac, Susan; Christensen, Mikkel & Hansen, Finn Knut (2011). Old treatments – new solutions? Summary of activities of the Alum Research Group. Full text in Research Archive
• Landsem, Eva; Tungen, Jørn Eivind; Kristensen, Tor Erik; Unneberg, Erik; Benneche, Tore & Hansen, Finn Knut (2011). Isocyanate-Free Curing of Glycidyl Azide Polymer (GAP). Full text in Research Archive
• Bourgeaux-Goget, Marie; Frømyr, Tomas Roll; Hansen, Finn Knut & Pinheiro, Jean Patrick (2010). Dispersion study of multi-wall carbon nanotubes synthesized by arc-discharge technique. Full text in Research Archive Show summary

  Carbon nanotubes (CNTs) have received a great amount of interest because of their intrinsic and unique chemical, physical and mechanical properties that are suitable for versatile applications, especially for composite materials. Unfortunately, these materials are plagued with challenging dispersion protocols concomitant with difficult characterization techniques which complicate discovering their comprehensive properties in composite products. Our approach uses CNTs synthesized by arc-discharge technique as they offer fewer structural defects than those produced by other known techniques. A method was developed to characterize the dispersed medium using disc centrifuge for the detection of individual CNTs and residual aggregates. Studies performed on both pristine and purified CNTs show that interactions in between nanotubes are rather strong and high ultra-sound intensity is required to achieve complete dispersion of CNT bundles. Achieving such dispersion is a key advantage suggesting better properties on future composite materials.

• Frømyr, Tomas Roll & Hansen, Finn Knut (2010). The effects of sonication on the degree of dispersion of carbon nanotubes in epoxy systems. Full text in Research Archive Show summary

  Epoxy systems filled with multiwall carbon nanotubes (MWNT) have been studied. It is generally believed that nanotubes must be well dispersed as single tubes in the matrix to utilize their excellent mechanical properties. Bath or tip sonicators are usually employed for the dispersion of the MWNTs. A bath sonicator treats the sample homogenously, but the power and the intensity is low. This results in very long sonication times to reach acceptable dispersions. Tip sonicators on the other hand, can have a high power output, but the acoustic field is very inhomogeneous. For larger volumes, stirring of the solution is necessary. Alternatively, the sonication can be done inside a flow-cell, resulting in a more homogenous sonication and a better ability to handle larger sample volumes. The efficiency of a bath sonicator has been compared with a tip sonicator in a flow-cell. Different types of MWNTs were dispersed in an epoxy curing agent. The degree of dispersion was determined by differential sedimentation particle analysis using a disc centrifuge. The results show that the particle size distribution is bi-modal with a narrow distribution of dispersed nanotubes and a broader distribution of agglomerates ranging from 100 nm to several micrometers in size. Furthermore, the separation of MWNTs from these agglomerates is controlled by a more complex mechanism than the energy input alone. At comparable energy inputs, a better dispersion is achieved using a higher acoustic intensity. The rate and degree of dispersion varies with different types of MWNTs.

• Truong, Le Thuy; Larsen, Åge; Holme, Børge; Hansen, Finn Knut & Roots, Jaan (2009). Morphology and crystallization behavior of syndiotactic polypropylene-alumina nanocomposites. Full text in Research Archive
• Truong, Le Thuy; Larsen, Åge Gellein; Holme, Børge; Diplas, Spyros; Hansen, Finn Knut & Roots, Jaan [Show all 7 contributors for this article] (2009). Dispersibility of Silane-functionalized Alumina Nanoparticles in Syndiotactic Polypropylene. Full text in Research Archive
• Christensen, Mikkel; Kutzke, Hartmut & Hansen, Finn Knut (2009). New materials used for the consolidation of archaeological wood – past attempts, present struggles, and future requirements. Full text in Research Archive
• Hansen, Finn Knut; Hansen, Tore & Kristensen, Tor Erik (2007). Solid phase organocatalysis. Full text in Research Archive Show summary

  Organocatalysis is a quite novel research field within asymmetric organic synthesis. Instead of the traditional metal based catalysts, small organic molecules, e.g. amino acids, have been shown to give interesting results. This has several advantages such as low cost, potential use in aqueous solutions, better biodegradability, no traces of metals and less health risk due to mild conditions. Almost all known organocatalytic processes are presently carried out under homogenous conditions. In order to increase the usability of these processes in practical applications, a heterogeneous catalytical process is necessary, but this has not yet been utilised significantly in organocatalysis. Different solid supports are used in bio-organic processes such as peptide synthesis, chromatography, ion exchange etc. These are either based on macroporous silica or solid or macroporous cross linked polymer particles. We have for many years been producing large (5 – 50 m) monodisperse macroporous polymer particles based on the Ugelstad method and similar processes for chromatography, biomedicin etc. These particles can be given functional groups such as double bonds, chloromethyl, hydroxyl, carboxyl, glycidyl, etc. which can be used to immobilize the organocatalysts. Different types of grafting can also be performed. The activity of these solid phase catalysts will be dependent of the type of catalyst, the structure of the particles, the method of binding, the degree of functionalization, etc.

• Hansen, Finn Knut & Grythe, Kai Frode (2005). Surface modification of EPDM rubber by plasma treatment. Full text in Research Archive
• Hansen, Finn Knut & Grythe, Kai Frode (2005). Surface modification of EPDM rubber by plasma treatment. Full text in Research Archive
• Grythe, Kai Frode; Hansen, Finn Knut & Walderhaug, Harald (2004). NMR Self Diffusion and Viscosity of Polyurethane Formulations for Rocket Propellants. Full text in Research Archive
• Hansen, Finn Knut & Kopperud, Hilde Beate Molvig (2000). Surface elasticity and viscosity of adsorbed films from drop shape analysis. Full text in Research Archive
• Hansen, Finn Knut (2000). Måling av overflateenergi av polymerer ved hjelp av kontaktvinkler av væsker på faste overflater. Full text in Research Archive
• Hansen, Finn Knut; Frømyr, T.; Laschewsky, A. & Kotzev, A. (1999). Adsorption and surface elastic properties of corresponding fluorinated and non-fluorinated cationic polymer films measured by drop shape analysis. Full text in Research Archive
• Hansen, Finn Knut; Nyström, Bo & Walderhaug, Harald (1996). Introduction. Colloids and Surfaces A: Physicochemical and Engineering Aspects. ISSN 0927-7757. 117, p. 17–17. Full text in Research Archive
• Hansen, Finn Knut; Nyström, Bo & Walderhaug, Harald (1994). Assosierende polymerer-et moderne og aktuelt forskningsfelt. Kjemi. ISSN 0023-1983. Full text in Research Archive
• Araba, Taofik Olasile; Bonge-Hansen, Tore & Hansen, Finn Knut (2016). Progress towards the synthesis and self-assembly of amphiphilic drug conjugates of Iodinin. Universitetet i Oslo. Full text in Research Archive
• Tesfu, Teame Kiros; Hansen, Finn Knut & Roots, Jaan (2016). Surface characterization of amphoteric and anionic membranes. Universitetet i Oslo. Full text in Research Archive Show summary

  ABSTRACT In recent years, the physical and chemical properties of hydrophilic surfaces been exploited in a number of novel applications. Especially, amphoteric membranes were the focus of many theoretical studies since they have a wide range of applications particularly in bio separation techniques. This particular study sought to determine surface characteristics of amphoteric and acidic membranes. Simple and reliable surface characterization method is important for understanding of membrane surface chemistry, separation performance and fouling resistance. Surface properties such as acid-base, hydrophilicity and hydrophobicity in which the performance of the polymer membranes is dependent on, were determined by contact angle using the immersion method. First, the surface properties of model commercial amphoteric membranes were characterized followed by lab-made amphoteric and acidic surfaces were investigated. A typical commercial amphoteric Blotting Nylon 6, 6, Type A membrane, plates of Polyoxymethylene modified by chromic acid as well as methyl acrylate based lab-made acidic and amphoteric membrane were examined. These new membranes were prepared using methyl methacrylate as monomer, di (ethylene glycol) diacrylate as cross linker, anionic methacrylic acid and cationic 2-(N, N-dimethyl amino) ethyl methacrylate as functional monomers. The syntheses were made by means of photo induced radical polymerization via camphorquinone/amine initiator. The contact angle titration curve for each membrane immersed in aqueous solution shows that the contact angle is sensitive to the degree of ionization of the surface functional groups. Moreover, surfactant adsorption property of the surfaces were determined using ceryl trimethylammonium bromide and sodium dodecyl benzene sulfonate (well below their critical micelle concentration) solutions as a function of pH. The contact angle titration curve in the presence of these surfactants describes the surface can go from hydrophilic to hydrophobic upon the adoption ionic surfactant depending on the pH, surface charge density and surfactant concentration. Furthermore, scanning electron microscopy (SEM) has been used to characterize surface morphology of the amphoteric and acidic surfaces. The SEM image of the commercial surface showed that, the surface has high porosity, rough, uneven, and the pore size and hydrophobicity increase upon the adsorption of ionic surfactant. However, polyethylene surface did not show any visible changes after treatment. In addition, SEM image of the synthesized amphoteric surface was also analyzed. From the results of this study, it can be concluded that the change in contact angle as a function pH is sensitive to the degree of ionization of surface functional groups. The adsorption of ionic surfactant is dependent on the membranes acidity, basicity and surfactant concentration as functions of pH. Besides, synthesis of membranes by photo polymerization of acrylate based monomers can be used for the preparation of functionalized surfaces. On top of that, based on the experiments done in this thesis, it can be concluded that the hydrophilicity, acidic and basic of surface groups can be determined using the immersed contact angle method. Therefore, it could be possible to suggest that determination of surface properties of anionic and/or basic surfaces using contact angle immersed method should be given emphasis for the development functionalized membranes.

• Chamgordani, Elahe Jafari; Benneche, Tore & Hansen, Finn Knut (2015). Synthesis of 5-Membered Heterocycles as Quorum Sensing Inhibitors. Universitetet i Oslo. Full text in Research Archive
• Truong, Thuy le; Larsen, Åge Gellein; Holme, Børge; Hansen, Finn Knut & Roots, Jaan (2013). Syndiotactic polypropylene nanocomposites and blends: Morphology, crystallization behavior and tensile properties. Universitetet i Oslo. Full text in Research Archive
• Christensen, Mikkel; Hansen, Finn Knut & Kutzke, Hartmut (2013). Developing new consolidants for archaeological wood. Universitetet i Oslo. Full text in Research Archive
• Landsem, Eva; Hansen, Finn Knut; Unneberg, Erik & Benneche, Tore (2012). Development of Smokeless Composite Rocket Propellants. Universitetet i Oslo. Full text in Research Archive
• Kristensen, Tor Erik Holt; Hansen, Tore & Hansen, Finn Knut (2010). Polymer-Supported Chiral Organocatalysts. Universitetet i Oslo. Full text in Research Archive
• Aardal, Joakim; Grorud, Mette; Hansen, Finn Knut; Olsen, Torbjørn & Grythe, Kai Frode (2009). Overflatemodifisering av silikongummi for å oppnå bedre adhesjon mot polare forbindelser. Forsvarets forskningsinstitutt . ISSN 9788246415543. Full text in Research Archive Show summary

  I dette arbeidet er ulike typer silikongummi overflatemodifisert på fem forskjellige måter; varmebehandling,plasmabehandling, syrebehandling, laserbehandling, og behandling med oksidasjonsmiddelethydrogenperoksid. Resultatene er evaluert ved hjelp av kontaktvinkelmålinger, og ienkelte tilfeller også XPS (X-ray photoelectron spectroscopy). Det ble benyttet ulike typersilikongummier; noen ble mottatt av Nammo fra leverandører, to typer ble støpt fra flytendeprepolymerer levert av Alpina, og fire ulike typer silikongummi ble levert av MomentivePerformance Materials. Varmebehandling skjedde opptil 300 oC. I syrebehandlingen ble detbenyttet saltsyre, svovelsyre og salpetersyre. I laserbehandlingen ble det benyttet en Nd:YAGlaser med bølgelengde 355 nm, og plasmabehandlingen ble utført i lavtrykks oksygenplasma.Varme- og syrebehandling gav, med ett unntak, kun mindre endringer i overflateenergien, selvom det fysiske utseendet endret seg forholdsvis mye. Svovelsyre er særlig nedbrytende forsilikongummi, men det påvirker i mindre grad overflateenergien. Kun en prøve ble i liten gradnedbrutt av syre, og denne viste tydelig nedsatt kontaktvinkel for vann. Laserbehandlingen gavkun mindre endringer i kontaktvinkelen, selv om det ble observert større fysiske endringer ioverflaten. Prøvene reagerte forholdsvis ulikt på de forskjellige behandlingsmetodene, men fellesfor alle var at den største endringen i overflateenergi ble oppnådd med plasmabehandling.

• Hansen, Finn Knut (1999). Modellbygging og forsøksplanlegging, Statistikk for kjemikere. Full text in Research Archive
• Hansen, Finn Knut (1999). Innhenting av data fra måleinstrumenter. Full text in Research Archive

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