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  • 151.
    Carlmark, Anna
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva E
    KTH, Superseded Departments, Fibre and Polymer Technology.
    ATRP of dendronized aliphatic macromonomers of generation one, two, and three2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 20, p. 7491-7496Article in journal (Refereed)
    Abstract [en]

    Atom transfer radical polymerization (ATRP) of dendritic, aliphatic macromonomers has been investigated. The macromonomers were based on acrylate functionalized 2,2-bis(methylol)propionic acid (bis-MPA) dendrons, with a flexible spacer of 10 carbons incorporated in the structure in between the polymerizable group and the dendritic wedge. Dendronized polymers of generation one, two, and three were successfully synthesized by ATRP. The polymerizations proceeded until over 80% conversion was reached, while maintaining control over polydispersity index (PDI). Plots of ln([M](0)/[M]) vs time for the polymerization of all three macromonomers showed a linear dependence, indicating that the number of propagating radicals in the reaction solution was constant throughout the reaction, when ethyl 2-bromopropionate (EBrP) was used as an initiator (i.e., radical termination was negligible). All of the resulting polymers had low PDI values and molecular weight close to the theoretical ones. The products were analyzed by H-1 and C-13 NMR spectroscopies, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF).

  • 152.
    Carlsson, Linn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interest in new environmentally friendly cellulose‐based productshas increased tremendously over the last years. At the same time theSwedish forest industry faces new challenges in its strive to increase the utilization of cellulose fibers in high‐value end‐products. The aim of this study was to expand the toolbox for surface modification of cellulose byemploying covalent surface‐initiated (SI) polymerizations or by physicaladsorption of polymers. SI‐ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) was performed from filter paper (FP) and high surface area nanopaper (NP).Larger amounts of polycaprolactone (PCL) were grafted from NP, compared to FP, owing to the higher amount of available initiating hydroxyl groups. Furthermore, the mechanical properties of PCL were improved by the grafting of FP and NP, as compared to pure PCL.It is challenging to characterize a polymer grafted from a surface. Hence, quartz crystal microbalance with dissipation (QCM‐D) was employed to investigate SI‐ROP in real time from a cellulose model surface. Furthermore, it was shown by colloidal probe AFM that increased lengthof grafted PCL, from cellulose microspheres, improved the interfacialadhesion to a pure PCL surface, suggesting that chain entanglements havea significant impact on the interfacial properties. Increased temperatureand time in contact also improved the adhesion.In order to investigate the degree of substitution (DS) and the degree of polymerization (DP), PCL‐grafted hydrolyzed cellulose cotton linters (HCCL) were studied by solid state NMR. It was found that despite a DS of only a few percent, the surface character changed considerably; furthermore, the DS was virtually independent of the DP. To increase theamount of grafted polymer, ring‐opening metathesis polymerization (ROMP) of norbornene was performed from FP. Short polymerizationtimes and low temperatures resulted in highly grafted surfaces. Alternatively, physical adsorption by electrostatic interactions was employed to modify a cellulose model surface in the QCM‐D. Cationic latex nanoparticles of poly(dimetylaminoethyl methacrylate‐co‐methacrylicacid)‐block‐poly(methyl methacrylate) were produced by reversible addition‐fragmentation chain‐transfer (RAFT)‐mediated surfactant‐freeemulsion polymerization by polymerization‐induced self‐assembly (PISA).This strategy does not require any organic solvents and could potentiallybe introduced in industrial processes.

  • 153.
    Carrick, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Macro-, Micro- and Nanospheres from Cellulose: Their Preparation, Characterization and Utilization2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The structure of a polymeric material has a great influence in many fundamental scientific areas as well as in more applied science, since it affects the diffusion, permeability, mechanical strength, elasticity, and colloidal properties of the materials. The results in this thesis demonstrate that it is possible to fabricate solid and hollow cellulose spheres with a cellulose shell and encapsulated gas, liquid or solid particles and with a sphere size ranging from a few hundreds of nanometres to several millimetres, all with a tailored design and purpose.

    The sizes of the different spheres have been controlled by three different preparation methods: large cellulose macrospheres by a solution solidification procedure, hollow micrometre-sized cellulose spheres by a liquid flow-focusing technique in microchannels, and nanometre-sized cellulose spheres by a membrane emulsification technique. 

    The spheres were then modified in different ways in order to functionalize them into more advanced materials. This thesis demonstrates how to control the cellulose sphere dimensions and the wall-to-void volume ratio, the elasticity and the functionality of the spheres as such, where they were prepared to be pH-responsive, surface specific and X-ray active. These modifications are interesting in several different types of final materials such as packaging materials, drug release devices or advanced in vivo diagnostic applications.

    In the more fundamental science approach, surface-smooth solid cellulose spheres were prepared for characterization of the macroscopic work of adhesion when a cellulose surface is separated from another material. Using these ultra-smooth macroscopic cellulose probes, it is possible to measure the compatibility and the surface interactions between cellulose and other materials which provide an important tool for incorporating cellulose into different composite materials. 

  • 154.
    Carrick, Christopher
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pendergraph, Samuel A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanometer Smooth, Macroscopic Spherical Cellulose Probes for Contact Adhesion Measurements2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 23, p. 20928-20935Article in journal (Refereed)
    Abstract [en]

    Cellulose spheres were prepared by dissolving cellulose fibers and subsequently solidifying the solution in a nonsolvent. Three different solution concentrations were tested and several nonsolvents were evaluated for their effect on the formation of spheres. Conditions were highlighted to create cellulose spheres with a diameter of similar to 1 mm and a root-mean-square surface roughness of similar to 1 nm. These solid spheres were shown to be easily chemically modified without changing the mechanical properties significantly. Contact adhesion measurements were then implemented with these spheres against a poly(dimethylsiloxane) (PDMS) elastomer in order to quantify the adhesion. Using Johnson-Kendall-Roberts (JKR) theory, we quantified the adhesion for unmodified cellulose and hydrophobic cellulose spheres. We highlight the ability of these spheres to report more accurate adhesion information, compared to spin-coated thin films. The application of these new cellulose probes also opens up new possibilities for direct, accurate measurement of adhesion between cellulose and other materials instead of using uncertain surface energy determinations to calculate the theoretical work of adhesion between cellulose and different solid materials.

  • 155.
    Carvalho, Danila
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Study on the structure and properties of xylan extracted from eucalyptus, sugarcane bagasse and sugarcane straw2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lignocellulosic biomasses are an important source of chemical components such as cellulose, lignin and hemicelluloses, and can be used for a variety of purposes in both the pulp and paper and chemical conversion industries. Xylan, the main hemicellulose found in hardwood and grass plants, plays an important role during the pulping/pretreatment process reactions, including those used in 2nd generation bioethanol production. It may also play an important role in the production of certain novel materials.

    This thesis evaluates the composition of eucalyptus (Eucalyptus urophylla x Eucalyptus grandis), sugarcane bagasse and sugarcane straw, with a specific focus on the structure and properties of xylan. The chemical characterization of biomasses showed that sugarcane bagasse and straw contain larger amounts of extractives, ash and silica than eucalyptus. The large amount of silica leads to an overestimation of the Klason lignin content, if not corrected. By using a complete mass balance approach, sugarcane bagasse and straw were shown to contain smaller amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much smaller amount of lignin than was found in eucalyptus (27.4%). The hemicellulose content in sugarcane bagasse (28.7%) and straw (29.8%) was much higher than that in eucalyptus (20.3%).

    In order to investigate the structure of the xylan in greater detail, it was extracted with dimethyl sulfoxide from holocellulose, obtained by either peracetic acid or sodium chlorite delignification. The structure of the isolated xylans was confirmed by FTIR and 1H NMR analysis. In eucalyptus, the O-acetyl-(4-O-methylglucurono)xylan (MGX) was identified. This had a molar ratio of xylose units to branches of 4-O-methylglucuronic acid of 10:1.1 and a degree of acetylation of 0.39. All 4-O- methylglucuronic acid groups were attached to position O-2 of the xylose units, which had an acetyl group in position O-3. The acetyl groups were distributed in positions O-3 (64%), O-2 (26%) and O-2,3 (10%). The MGX had a molecular weight (Mw) of about 42 kDa.

    In bagasse and straw, arabinoxylan (AX) was identified. This had a molar ratio of xylose units to arabinosyl substitutions of 10:0.5 for bagasse and 10:0.6 for straw. A degree of acetylation was 0.29 and 0.08 for bagasse and straw, respectively. The arabinose units were attached preferentially to position O-3 in AX. In the xylan from bagasse, the acetyl groups were found in positions O-3 (60%), O-2 (13%) and O-2,3 (27%), while in the xylan from straw, the acetyl groups were distributed between positions O-3 (67%) and O-2 (33%). The AX had a molecular weight (Mw) of about 38 kDa and 30 kDa for bagasse and straw, respectively.

    The differences in the structure of xylan present in the various biomasses played an important role during hydrothermal pretreatment, which is often used as the first step in 2nd generation ethanol production. The varying amounts of uronic acid and acetyl groups resulted in different starting pH levels of liquor and, thus, affected the chemical transformation in the biomasses in different ways. The hydrothermal pretreatment resulted mostly in the removal and/or transformation of hemicelluloses, but also in the formation of a significant number of pseudo-lignin structures. In addition, in eucalyptus, pseudo-extractives structures were generated. The sugarcane straw showed the highest mass loss during the investigated pretreatment.

  • 156. Cataldi, A.
    et al.
    Dorigato, A.
    Deflorian, F.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pegoretti, A.
    Polymer composite with micro- and nanocellulose for artwork protection and restoration2014In: 16th European Conference on Composite Materials, ECCM 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Micro- and nanocomposites were prepared using Aquazol® 500 as a polymeric matrix and a microcrystalline cellulose (MCC), and suspensions of cellulose nanocrystals (CNC), as reinforcing agents. After a preliminary thermo-mechanical characterization that highlighted a stabilizing effect due to the micro- and nanofiller introduction, with an increase of the elastic modulus and a decrease of the thermal expansion coefficient and the creep compliance [1], these materials were applied as canvas lining adhesives. Single-lap shear tests both in quasi-static and creep conditions confirmed the dimensional stability provided by cellulose micro- and nanoparticles, with an important reduction of the adhesives compliance proportional to the filler content. Interestingly, MCC and CNC introduction did not impair the fracture behavior of the neat matrix.

  • 157.
    Celsi, Adrian
    KTH, School of Chemical Science and Engineering (CHE).
    Developmental lignocellulose mapping in crop stems2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With current techniques there is no rapid, one-step alternative to investigate plant composition and anatomy. In this study we present the use of luminescent

    conjugated oligothiophene (LCO), as a carbohydrate marker in unused cash crop stems. Stem samples were analyzed between day 0-75 using FTIR, gas

    chromatography, confocal laser scanning microscopy and spectral imaging analysis. Carbohydrate composition analysis confirmed cellulose presence in all

    time points tested and that fractions of monosaccharaides stay constant in the stem during growth. Using confocal and fluorescence microscopy, emission from

    LCO bound to cellulose was detected and stem composition and anatomy visualized.

    Overall, we demonstrate that LCOs can be utilized for compositional analyzes in plant tissues as a non-destructive and one-step alternative to today’s techniques.

    This method shows high applicability for structure and anatomy studies in plant tissues, but also as a compliment for current composition analysis techniques.

     

  • 158.
    Cervin, Nicholas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Porous Cellulose Materials from Nano Fibrillated Cellulose2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the first part of this work a novel type of low-density, sponge-like material for the separation of mixtures of oil and water has been prepared by vapour deposition of hydrophobic silanes on ultra-porous nanocellulose aerogels. To achieve this, a highly porous (> 99 %) nanocellulose aerogel with high structural flexibility and robustness is first formed by freeze-drying an aqueous dispersion of the nanocellulose. The density, pore size distribution and wetting properties of the aerogel can be tuned by selecting the concentration of the nanocellulose dispersion before freeze-drying. The hydrophobic light-weight aerogels are almost instantly filled with the oil phase when they selectively absorb oil from water, with a capacity to absorb up to 45 times their own weight. The oil can also be drained from the aerogel and the aerogel can then be subjected to a second absorption cycle.In the second part of the work a novel, lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified NanoFibrillated Cellulose (NFC). Confocal microscopy and high-speed video imaging show that the long-term stability of the wet foams can be attributed to the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface which prevent the air bubbles from collapsing or coalescing. Careful removal of the water yields a porous cellulose-based material with a porosity of 98 % and a density of 30 mg cm-3. These porous cellulose materials have a higher Young’s modulus than other cellulose materials made by freeze drying and a compressive energy absorption of 56 kJ m-3 at 80 % strain. Measurements with an autoporosimeter reveal that most pores are in the range of 300 to 500 μm.

  • 159.
    Cervin, Nicholas Tchang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johansson, E.
    Benjamins, J. -W
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Mechanisms behind the Stabilizing Action of Cellulose Nanofibrils in Wet-Stable Cellulose Foams2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 3, p. 822-831Article in journal (Refereed)
    Abstract [en]

    The principal purpose of the investigation was to clarify the mechanisms behind the stabilizing action of cellulose nanofibrils (CNFs) in wet-stable cellulose foams. Following the basic theories for particle-stabilized foams, the investigation was focused on how the surface energy of the stabilizing CNF particles, their aspect ratio and charge density, and the concentration of CNF particles at the air-water interface affect the foam stability and the mechanical properties of a particle-stabilized air-liquid interface. The foam stability was evaluated from how the foam height changed over time, and the mechanical properties of the interface were evaluated as the complex viscoelastic modulus of the interface using the pendant drop method. The most important results and conclusions are that CNFs can be used as stabilizing particles for aqueous foams already at a concentration as low as 5 g/L. The major reasons for this were the small dimensions of the CNF and their high aspect ratio, which is important for gel-formation and the complex viscoelastic modulus of the particle-filled air-water interface. The influence of the aspect ratio was also demonstrated by a much higher foam stability of foams stabilized with CNFs than of foams stabilized by cellulose nanocrystals (CNC) with the same chemical composition. The charge density of the CNFs affects the level of liberation within larger aggregates and hence also the number of contact points at the interface and the gel formation and complex viscoelastic modulus of the air-water interface. The charges also result in a disjoining pressure related to the long-range repulsive electrostatic pressure between particle-stabilized bubbles and hence contribute to foam stability. (Figure Presented).

  • 160. Champ, Simon
    et al.
    Koch, Oliver
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Feuerhake, Robert
    Haehnle, Hans-Joachim
    Biocidal coatings2006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Biocidal multilayered system, characterized in that it comprises at least the following layers: - an anionic or cationic carrier, preferably cellulose as anionic carrier, - on this carrier alternating polymeric cationic and anionic layers starting with a layer having a charge opposite to that of the carrier, - wherein at least one layer is hydrophobically modified.

  • 161. Chang, B.
    et al.
    Schneider, K.
    Patil, N.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY, Hamburg, Germany.
    Heinrich, G.
    Microstructure characterization in a single isotactic polypropylene spherulite by synchrotron microfocus wide angle X-ray scattering2018In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 142, p. 387-393Article in journal (Refereed)
    Abstract [en]

    Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75° with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%–56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 °C and it decreases to 0.11 as the crystallization temperature is decreased to 130 °C. The b-axis and c-axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a-axis prefers to align in the radius direction.

  • 162.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, p. 649-658Article in journal (Refereed)
    Abstract [en]

    Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

  • 163. Chen, F.
    et al.
    Nilsson, F.
    Gällstedt, M.
    RISE, Innventia.
    Hedenqvist, M.S.
    Chitosan extrusion at high solids content: An orthogonal experimental design study2014In: Polymers from Renewable Resources, ISSN 2045-1377, Vol. 5, no 1, p. 1-12Article in journal (Refereed)
  • 164.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Monnier, Xavier
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gällstedt, Mikael
    Innventia, Sweden.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Wheat gluten/chitosan blends: A new biobased material2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 60, p. 186-197Article in journal (Refereed)
    Abstract [en]

    Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 mu m wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 mu m). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 mu m and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.

  • 165.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, M.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Chitosan extrusion at high solids content: An orthogonal experimental design study2014In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 5, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    For economic reasons and to save time there is a need to shorten the drying operation associated with the production of chitosan materials. Hence it is of interest to extrude chitosan at as high a solids content as possible. This is, to our knowledge, the first systematic study of the extrusion of chitosan at high solids content (60 wt%). An orthogonal experimental design was used to evaluate the effect of processing conditions and material factors on the extrudability of chitosan. This, together with the examination of the evenness and surface finish of the extrudate, made it possible to determine the best conditions for obtaining a readily extrudable high quality material. It was observed that a 1/1 ratio of chitosans with molar masses of 12 and 133 kDa, a process liquid containing 30 wt% acetic acid and 70 wt% water, and extrusion at 50 rpm and 50°C were the optimal material and processing conditions. Materials processed under these conditions were evaluated mechanically at different times after extrusion (stored at 50% RH) in order to see when the properties stabilized. Most mass loss occurred within the first three days after extrusion and this governed the mechanical properties (stiffness and extensibility), which also exhibited the largest changes within these three days (an increase in modulus from 18 to 830 MPa and a decrease in elongation at break from 17 to 3%).

  • 166.
    Christophliemk, Hanna
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ullsten, Henrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Johansson, Caisa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Järnström, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Starch-poly(vinyl alcohol) barrier coatings for flexible packaging paper and their effects of phase interactions2017In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 111, p. 13-22Article in journal (Refereed)
    Abstract [en]

    Starch and poly(vinyl alcohol) based barrier coatings for flexible packaging papers were studied. Both octenyl succinate modified and hydroxypropylated corn and potato starches were blended with regular and ethylene modified poly(vinyl alcohol) to increase the water vapor barrier properties and enhance the flexibility of the starch coatings, in order to accomplish superior barrier performance. Phase separation between starch and poly (vinyl alcohol) was studied in detail, both in the solution and in dry draw-down coatings on paper. The barrier performance of the coated paper was evaluated with respect to water vapor transmission rate. Conditions for the creation of a thin surface layer consisting of only one of the pure polymers were identified and discussed in terms of phase separation in solution migration of poly(vinyl alcohol) to the uppermost surface layer. The phase separation promoted low water vapor transmission rates also with a rather high fraction of starch in the coatings

  • 167.
    Claesson, Hans
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Polymer Technology.
    Johansson, Mats K. G.
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Doyle, M.
    Manson, J. A. E.
    Rheological behaviour during UV-curing of a star-branched polyester2002In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 44, no 1, p. 63-67Article in journal (Refereed)
    Abstract [en]

    Using a rheometer coupled with an UV-light generator, the viscoelastic behaviour during the fast cure of star-branched polyester is investigated. The 32 arm star polymers consist of a hyperbranched polyester core, Boltorn(TM) and linear grafts of poly(E-caprolactone) (degree of polymerisation: 20-52) with methacrylate end groups. The resins are crystalline and the melting points range from 34 to 50degreesC; films can be formed and cured below 80degreesC. The crossover of G' and G was used as the gel point. The time to reach the gel point, a few seconds, increases linearly with molecular weight.

  • 168.
    Claesson, Hans
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Scheurer, Curzio
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Johansson, Mats K. G.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Paulus, W.
    Schwalm, R.
    Semi-crystalline thermoset resins: tailoring rheological properties in melt using comb structures with crystalline grafts2004In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 49, no 1, p. 13-22Article in journal (Refereed)
    Abstract [en]

    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.

  • 169.
    Cobo Sanchez, Carmen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Inorganic and organic polymer-grafted nanoparticles: their nanocomposites and characterization2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanocomposites (NCs) have been widely studied in the past decades due to the promising properties that nanoparticles (NPs) offer to a polymer matrix, such as increased thermal stability and non-linear electrical resistivity. It has also been shown that the interphase between the two components is the key to achieving the desired improvements. In addition, polymer matrices are often hydrophobic while NPs are generally hydrophilic, leading to NP aggregation. To overcome these challenges, NPs can be surface-modified by adding specific molecules and polymers. In the present work, a range of organic and inorganic NPs have been surface-modified with polymers synthesized by atom transfer radical polymerization (ATRP) or surface-initiated ATRP (SI-ATRP).Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) are highly crystalline NPs that can potentially increase the Young’s modulus of the NC. In this study, a matrix-free NC was prepared by physisorption of a block-copolymer containing a positively charged (quaternized poly(2-(dimethylamino)ethyl methacrylate), qPDMAEMA) and a thermo-responsive (poly di(ethylene glycol) methyl ether methacrylate, PDEGMA). The modified CNF exhibited a thermo-responsive, reversible behavior. CNCs were polymer-modified either via SI-ATRP or physisorbed with poly (butyl methacrylate) (PBMA) to improve the dispersion and interphase between them and a polycaprolactone (PCL) matrix during extrusion. The mechanical properties of the NCs containing CNC modified via SI-ATRP were superior to the reference and unmodified materials, even at a high relative humidity.Reduced graphene oxide (rGO) and aluminum oxide (Al2O3) are interesting for electrical and electronic applications. However, the matrices used for these applications, such as poly(ethylene-co-butyl acrylate) (EBA) and low density polyethylene (LDPE) are mainly hydrophobic, while the NPs are hydrophilic. rGO was modified via SI-ATRP using different chain lengths of PBMA and subsequently mixed with an EBA matrix. Al2O3 was modified with two lengths of poly(lauryl methacrylate) (PLMA), and added to LDPE prior to extrusion. Agglomeration and dispersion of the NCs were dependent on the lengths and miscibilities of the grafted polymers and the matrices. rGO-EBA NCs showed non-linear direct current (DC) resistivity upon modification, as the NP dispersion improved with increasing PBMA length. Al2O3-LDPE systems improved the mechanical properties of the NCs when low amounts of NPs (0.5 to 1 wt%) were added, while decreasing power dissipation on the material.Finally, PLMA-grafted NPs with high polymer quantities and two grafting densities in Al2O3 and silicon oxide (SiO2) nanoparticles were synthesized by de-attaching some of the silane groups from the surfaces, either by hydrolysis or by a mild tetrabutylammonium fluoride (TBAF) cleavage. These compounds were characterized and compared to the bulk PLMA, and were found to have very interesting thermal properties.

    The full text will be freely available from 2020-04-24 14:42
  • 170.
    Cobo Sanchez, Carmen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Matrix-free Nanocomposites based on Poly(lauryl methacrylate)-Grafted Nanoparticles: Effect of Graft Length and Grafting DensityManuscript (preprint) (Other academic)
    The full text will be freely available from 2020-04-24 14:17
  • 171.
    Colson, Jerome
    et al.
    Univ Nat Resources & Life Sci Vienna, Dept Mat Sci & Proc Engn, Inst Wood Technol & Renewable Mat, Konrad Lorenz Str 24, A-3430 Tulin, Austria..
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Asaadi, Shirin
    Aalto Univ, Sch Chem Engn, Dept Bioprod & Biosyst, Vuorimiehentie 1, Espoo 02150, Finland..
    Sixta, Herbert
    Aalto Univ, Sch Chem Engn, Dept Bioprod & Biosyst, Vuorimiehentie 1, Espoo 02150, Finland..
    Nypelo, Tiina
    Chalmers Univ Technol, Dept Chem & Chem Technol, Kemigarden 4, S-41296 Gothenburg, Sweden..
    Mautner, Andreas
    Univ Vienna, Fac Chem, Inst Mat Chem & Res, Wahringer Str 42, A-1090 Vienna, Austria..
    Konnerth, Johannes
    Univ Nat Resources & Life Sci Vienna, Dept Mat Sci & Proc Engn, Inst Wood Technol & Renewable Mat, Konrad Lorenz Str 24, A-3430 Tulin, Austria..
    Adhesion properties of regenerated lignocellulosic fibres towards poly (lactic acid) microspheres assessed by colloidal probe technique2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 532, p. 819-829Article in journal (Refereed)
    Abstract [en]

    In the field of polymer reinforcement, it is important to understand the interactions involved between the polymer matrix and the reinforcing component. This paper is a contribution to the fundamental understanding of the adhesion mechanisms involved in natural fibre reinforced composites. We report on the use of the colloidal probe technique for the assessment of the adhesion behaviour between poly(lactic acid) microspheres and embedded cross-sections of regenerated lignocellulosic fibres. These fibres consisted of tailored mixtures of cellulose, lignin and xylan, the amount of which was determined beforehand. The influence of the chemical composition of the fibres on the adhesion behaviour was studied in ambient air and in dry atmosphere. In ambient air, capillary forces resulted in larger adhesion between the sphere and the fibres. Changing the ambient medium to a dry nitrogen atmosphere allowed reducing the capillary forces, leading to a drop in the adhesion forces. Differences between fibres of distinct chemical compositions could be measured only on freshly cut surfaces. Moreover, the surface energy of the fibres was assessed by inverse gas chromatography. Compared to fibres containing solely cellulose, the presence of lignin and/or hemicellulose led to higher adhesion and lower surface energy, suggesting that these chemicals could serve as natural coupling agents between hydrophobic and hydrophilic components.

  • 172. Cozzolino, Carlo A.
    et al.
    Campanella, Gaetano
    Ture, Hasan
    Olsson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Farris, Stefano
    Microfibrillated cellulose and borax as mechanical, O-2-barrier, and surface-modulating agents of pullulan biocomposite coatings on BOPP2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 143, p. 179-187Article in journal (Refereed)
    Abstract [en]

    Multifunctional composite coatings on bi-oriented polypropylene (BOPP) films were obtained using borax and microfibrillated cellulose (MFC) added to the main pullulan coating polymer. Spectroscopy analyses suggested that a first type of interaction occurred via hydrogen bonding between the C-6-OH group of pullulan and the hydroxyl groups of boric acid, while monodiol and didiol complexation represented a second mechanism. The deposition of the coatings yielded an increase in the elastic modulus of the entire plastic substrate (from similar to 2 GPa of the neat BOPP to similar to 3.1 GPa of the P/B+/MFC-coated BOPP). The addition of MFC yielded a decrease of both static and kinetic coefficients of friction of approximately 22% and 25%, respectively, as compared to the neat BOPP. All composite coatings dramatically increased the oxygen barrier performance of BOPP, especially under dry conditions. The deposition of the high hydrophilic coatings allowed to obtain highly wettable surfaces (water contact angle of similar to 18 degrees).

  • 173.
    Crispin, Xavier
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Marciniak, S.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Osikowicz, Wojciech
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Zotti, G.
    Instituto Consiglio Nazionale delle Ricerche per l' Energetica e le Interfasi, Padova, Italy.
    Denier Van Der Gon, A. W.
    Faculty of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands.
    Louwet, F.
    Chemistry Department, R&D Materials Research, Agfa Gevaert N.V., Mortsel, Belgium.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Groenendaal, L.
    Chemistry Department, R&D Materials Research, Agfa Gevaert N.V., Mortsel, Belgium.
    De Schryver, F.
    Afdeling Fotochemie en Spectroscopie, Katholieke Universiteit Leuven, Heverlee, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Conductivity, Morphology, Interfacial Chemistry, and Stability of Poly(3,4- ethylene dioxythiophene)–Poly(styrene sulfonate): A Photoelectron Spectroscopy Study2003In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 41, no 21, p. 2561-2583Article, review/survey (Refereed)
    Abstract [en]

    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.

  • 174.
    Cunha, Ana Gisela
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. INNVENTIA AB, Sweden.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Topochemical acetylation of cellulose nanopaper structures for biocomposites: mechanisms for reduced water vapour sorption2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2773-2787Article in journal (Refereed)
    Abstract [en]

    Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m(2)/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS C-13-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites.

  • 175.
    Danish, Muhammad
    et al.
    East China University of Science and Technology, Shanghai, China.
    Gu, Xiaogang
    East China University of Science and Technology, Shanghai, China.
    Lu, Shuguang
    East China University of Science and Technology, Shanghai, China.
    Farooq, Usman
    East China University of Science and Technology, Shanghai, China.
    Ahmad, Ayyaz
    University of Engineering and Technology, Multan, Pakistan.
    Naqvi, Muhammad
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Xue, Yunfei
    East China University of Science and Technology, Shanghai, China.
    Zhang, Xiang
    East China University of Science and Technology, Shanghai, China.
    Effect of solution matrix and pH in Z-nZVI-catalyzed percarbonate system on the generation of reactive oxygen species and degradation of 1, 1, 1-trichloroethane2017In: Water Science and Technology: Water Supply, ISSN 1606-9749, E-ISSN 1607-0798, Vol. 17, no 6, p. 1568-1578Article in journal (Refereed)
    Abstract [en]

    This study primarily focuses on evaluating the effects of solution matrix and pH for the generation of reactive oxygen species (ROSs) in Z-nZVI-catalyzed sodium percarbonate (SPC) system to degrade 1,1,1-trichloroethane (1,1,1-TCA) in the absence and presence of reducing agent (RA) i.e. hydroxylamine. 1,1,1-TCA degradation was 49.5% and 95% in the absence and presence of RA. Probe tests confirmed the generation of major hydroxyl radicals (OH•) and minor superoxide species (O2–•), and scavenger tests verified the key role of OH• and less of O2–• radicals. 1,1,1-TCA degradation decreased significantly in the presence of Cl− and HCO3–, while NO3– and SO42– have negligible effects in absence of RA. Addition of RA significantly enhanced 1,1,1-TCA degradation by generating more OH• and O2–• radicals in presence of anions. 1,1,1-TCA degradation increased in acidic range (1–5) while, an inhibitive trend from neutral to basic (7–9) was observed. On the contrary, a significant increase in 1,1,1-TCA degradation was observed with addition of RA in all pH values (1–9). In conclusion, the anions and pH significantly influenced the generation and intensity of ROSs and 1,1,1-TCA was effectively degraded in Z-nZVI-catalyzed SPC system in the presence of RA.

  • 176.
    Das, Oisik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Johansson, E.
    Olsson, Richard
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Loho, T. A.
    Capezza, Antonio J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Singh Raman, R. K.
    Holder, Shima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    An all-gluten biocomposite: Comparisons with carbon black and pine char composites2019In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 120, p. 42-48Article in journal (Refereed)
    Abstract [en]

    Three different charcoals (gluten char, pine bark char and carbon black) were used to rectify certain property disadvantages of wheat gluten plastic. Pyrolysis process of gluten was investigated by analysing the compounds released at different stages. Nanoindentation tests revealed that the gluten char had the highest hardness (ca. 0.5 GPa) and modulus (7.8 GPa) followed by pine bark char and carbon black. The addition of chars to gluten enhanced the indenter-modulus significantly. Among all the charcoals, gluten char was found to impart the best mechanical and water resistant properties. The addition of only 6 wt% gluten char to the protein caused a substantial reduction in water uptake (by 38%) and increase of indenter-modulus (by 1525%). It was shown that it is possible to obtain protein biocomposites where both the filler and the matrix are naturally sourced from the same material, in this case, yielding an all-gluten derived biocomposite.

  • 177. Dax, Daniel
    et al.
    Soledad Chavez, Maria
    Xu, Chunlin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Process Chemistry Centre, C/o Laboratory of Wood and Paper Chemistry, Åbo Akademi University, Finland .
    Willfor, Stefan
    Teixeira Mendonca, Regis
    Sanchez, Julio
    Cationic hemicellulose-based hydrogels for arsenic and chromium removal from aqueous solutions2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 111, p. 797-805Article in journal (Refereed)
    Abstract [en]

    In this work the synthesis of hemicellulose-based hydrogels and their application for the removal of arsenic and chromium ions is described. In a first step O-acetyl galactoglucomannan (GGM) was subjected to a transesterification applying glycidyl methacrylate (GMA) for the synthesis of novel GGM macromonomers. Two distinguished and purified GGM fractions with molar mass of 7.1 and 28 kDa were used as starting materials. The resulting GGM macromonomers (GGM-MA) contained well-defined amounts of methacrylate groups as determined by H-1 NMR spectroscopy. Selected GGM-MA derivatives were consecutively applied as a crosslinker in the synthesis of tailored hydrogels using [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA) as monomer. The swelling rate of the hydrogels was determined and the coherence between the swelling rate and the hydrogel composition was examined. The morphology of the GGM-based hydrogels was analysed by SEM and the hydrogels revealed a high surface area and were assessed in respect to their ability to remove arsenate and chromate ions from aqueous solutions. The presented bio-based hydrogels are of high interest especially for the mining industries as a sustainable material for the treatment of their highly contaminated wastewaters.

  • 178.
    de Carvalho, Danila Morais
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Federal University of Viçosa, Brazil.
    Colodette, Jorge Luiz
    Comparative Study of Acid Hydrolysis of Lignin and Polysaccharides in Biomasses2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 6907-6923Article in journal (Refereed)
    Abstract [en]

    Effects of different acid hydrolysis conditions were studied relative to the chemical transformations of lignin in eucalyptus, sugarcane bagasse, and sugarcane straw, and on the transformations of multiple polysaccharides in eucalyptus. The acid hydrolysis using 12 mol/L sulfuric acid followed by acid hydrolysis using approximately 0.41 mol/L sulfuric acid was used as the reference for the lignin and sugar analysis. During acid hydrolysis, the relative amount of lignin increased with longer reaction times and/or greater acid concentrations for all biomasses. The overestimation of lignin in harsher acidic conditions resulted from the summation of lignocellulosic-derivatives (pseudo- lignin) together with lignin itself. Lignin reactions (dissolution/deposition) for bagasse and straw occurred in a greater extent than for eucalyptus, considering similar conditions of acid hydrolysis. The sugar transformation during acid hydrolysis was also investigated for eucalyptus. The sugar content quantified in eucalyptus decreased as the acid concentration and/or reaction time in the second hydrolysis increased. Glucose, galactose, and mannose were more resistant to harsher acidic conditions than xylose and arabinose. However, the most severe conditions (121 degrees C, 90 min, and 6.15 mol/L H2SO4) caused complete sugar degradation.

  • 179.
    Decrop, Deborah
    et al.
    KU Leuven, Belgium.
    Pardon, Gaspard
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Kokalj, Tadej
    KU Leuven, Belgium.
    Robert, Puers
    KU Leuven, Belgium.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Lammertyn, Jeroen
    KU Leuven, Belgium.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer2015In: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.

  • 180.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose degradation in the Vasa: The role of acids and rust2013In: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, Vol. 58, no 4, p. 308-313Article in journal (Refereed)
    Abstract [en]

    The oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron-rich surface wood differs from the interior wood in that it displays higher pH and cellulose with higher molecular weight. The objective of this study was to determine why there is a difference in cellulose degradation, pH, and oxalic acid amount between the surface region and the interior of the Vasa timbers. Analysis of cellulose weight average molecular weight by size exclusion chromatography was performed, as well as quantification of oxalic acid and iron by high-performance anion exchange chromatography and atomic emission spectroscopy, respectively. It was found that a decrease in iron content coincides with an increase in oxalic acid concentration and a drop in pH at a certain depth from the wood surface. When iron-rich surface wood samples from the Vasa were mixed with an aqueous solution of oxalic acid, a fast increase of pH over time was observed. Neither interior wood poor in iron nor the fresh oak reference showed the same neutralizing effect during the time of measurement. This indicates that the presence of iron (rust) causes a neutralization of the wood, through the formation of iron(III) oxalato complexes, thus protecting the wood from oxalic acid hydrolysis. This effect was not observed to the same extent for other acids observed in Vasa wood (sulfuric, formic, glycolic, and acetic acids).

  • 181.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Degradation reactions in vasa wood2011In: Shipwrecks 2011, 2011, p. 114-116Conference paper (Refereed)
  • 182.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    Sandberg, Teresia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chemical analysis of wood extractives and lignin in the oak wood of the 380 year old Swedish warship Vasa2011Conference paper (Refereed)
    Abstract [en]

    In order to map the source of oxalic acid in the interior wood of the Vasa ship, an analysis of wood extractives (tannins) was conducted. Samples used for analysis were PEG-impregnated dry Vasa wood, waterlogged Vasa wood and a reference material (fresh oak). The wood material was ground and extracted with an acetone/water-mixture. In the reference sample, several types of tannins were found such as the isomers castalagin/vescalagin and grandinin and their dimmers roburin A/D and roburin B/C respectively. The results have been confirmed by NMR spectroscopy and MALDI-TOF. The interior of the waterlogged Vasa wood contained small amounts of monomers, whereas the dry, PEG treated Vasa revealed no discernible amounts of hydrolysable tannins or other easily soluble compounds. Furthermore, an analysis of lignin was made by means of chemical degradation (thioacidolysis). A decrease in the amount of β-O-4 bonds in the lignin structure would imply a formation of easily oxidized free phenolics. The products were analyzed by GC-MS, which revealed no dramatic differences between the Vasa samples and the reference. The results were confirmed by CP/MAS NMR by analyzing the differences in the aromatic region (150∼160 ppm) as well as the carbonyl region (190∼200 ppm).

  • 183.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sandberg, Teresia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Analysisof lignin and extractives in the oak wood of the 17th century warship Vasa2011Manuscript (preprint) (Other (popular science, discussion, etc.))
  • 184. Di Filippo, Maria
    et al.
    Alessi, Sabina
    Pitarresi, Giuseppe
    Sabatino, Maria Antonietta
    Zucchelli, Andrea
    Dispenza, Clelia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Univ Palermo, Italy.
    Hydrothermal aging of carbon reinforced epoxy laminates with nanofibrous mats as toughening interlayers2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 126, p. 188-195Article in journal (Refereed)
    Abstract [en]

    Electrospun mats have been applied as toughening interlayers in high performance carbon fiber epoxy composites. While the toughening mechanism exerted by the mat at the interface is the subject of several recent studies, no investigations are reported on the aging behaviour of laminates comprising these nanostructured elements. This work investigates the influence of the combined effect of water and temperature (90 degrees C) on laminates with Nylon 6,6 electrospun membranes placed either at the middle plane only or at each interlayer. The water-uptake behaviour is modelled by a two-stage diffusion model and compared with the behaviour of the neat resin and of the laminate without mats. Interestingly, a lower water uptake is observed for the laminates with mat-modified interfaces and this is possibly due to a significantly reduced porosity. The effect of hydrothermal aging on the thermal (Tg) and mechanical properties (transverse flexural modulus and interlaminar shear strength) of the various laminates is also investigated.

  • 185.
    Dinko, Lukes
    KTH, School of Chemical Science and Engineering (CHE).
    Quantification of acid diffusion in fluoroplastic materials2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To improve the service reliability of polymeric materials used in corrosive environments more corrosion data such as diffusion of acids is needed. The aim of this research was to investigate the diffusion of acids mainly in fluoroplastic materials by optimizing quantitative and qualitative methods to measure the diffusion. It was found that ion chromatography could be used to measure the acid concentration found inside the different polymers by desorption into a water solution. The amount of ions was then recalculated and presented as gacid/gpolymer. The polymeric materials were exposed in hydrochloric acid, nitric acid, hydrobromic acid and mixed acid. Very large spreading was seen within each series for the polymers in the different acids resulting in very high standard deviations on the concentrations of acids. The cause of the spreading was not found,  but analyses on the acid concentration using inductively coupled plasma (ICP) verified the large spreading seen from the ion chromatograph and conclusions were drawn that the ion chromatography did not cause the spreading. Changes to the experimental procedure were made but did not resolve the problem. The solubility of hydrogen chloride was measured in the fluoropolymers: perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF) and ethylene-chlorotrifluoroethylene (ECTFE) and compared to the polyolefins: polyethylene (PE) and polypropylene (PP). It was found that the polyolefins had the highest solubility of hydrogen chloride and ECTFE had the lowest. Chlorine dioxide solubility in PVDF was established through a different approach, the LGB-method, but the problem with spreading was seen on these results as well. An indicator technique was used to calculate diffusion rates of HCl in polypropylene samples with successful results. However, the indicator technique did not work for the ECTFE samples.

  • 186.
    Djahedi, Cyrus
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. Wallenberg Wood Science Center.
    Deformation of cellulose allomorphs studied by molecular dynamics2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cellulose-based materials draw their good mechanical properties from the cellu-lose crystal. Improved understanding of crystal properties could lead to a wider range of applications for cellulose-based materials, Cellulose crystals show high axial Youngs modulus. Cellulose can attain several allomorphic forms which show unique structural arrangements in terms of both intra-molecular and inter-molecular bonding, as well as unit cell parameters and chain packing. Although several studies have confirmed that mechanical tensile properties of cellulose differ between different allomorphic forms, few reports have investigated the deformation mechanisms explaining the differences.In the first part of this thesis, the tensile elastic Youngs modulus of cellulose allo-morphs Iβ, II and III I were calculated under uniform conditions using Molecular Dynamics simulation techniques. As expected, a difference in modulus valuesc ould be observed, and the cooperative nature of energy contributions to crys-tal modulus is apparent. The allomorphs also show large differences in terms of how contributions to elastic energy are distributed between covalent bonds,angles, dihedrals, electrostatic forces, dispersion and steric forces.In the second part of this thesis, the cellulose Iβ and II allomorphs were sub-jected to a more detailed structural study. The purpose was to clarify how the deformation of the central glucosidic linkage between the monomer units depends on the hydrogen-bonding structures. This was carried out by studying simulated vibrational spectra and local deformations in the crystals.The results presented in this thesis confirm the differences in the tensile elastic properties of these cellulose allomorphs. These differences can in part be explained by the different intra-molecular hydrogen bonding patterns between allomorphs. Deformation mechanisms are discussed. The results are in supportof the so called ”leverage effect” proposed in the literature. The present analysis shows significant differences in details of deformation mechanisms compared with previous simpler analyses.

  • 187. Djahedi, Cyrus
    et al.
    Bergenstrahle-Wohlert, Malin
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Role of hydrogen bonding in cellulose deformation: the leverage effect analyzed by molecular modeling2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 4, p. 2315-2323Article in journal (Refereed)
  • 188.
    Duval, Antoine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    A review on lignin-based polymeric, micro- and nano-structured materials2014In: Reactive & functional polymers, ISSN 1381-5148, E-ISSN 1873-166X, Vol. 85, no SI, p. 78-96Article, review/survey (Refereed)
    Abstract [en]

    Next to cellulose, lignin is the second most abundant biopolymer, and the main source of aromatic structures on earth. It is a phenolic macromolecule, with a complex structure which considerably varies depending on the plant species and the isolation process. Lignin has long been obtained as a by-product of cellulose in the paper pulp production, but had rather low added-value applications. Changes in the paper market have however stimulated the need to focus on other applications for lignins. In addition, the emergence of biorefinery projects to develop biofuels, bio-based materials and chemicals from carbohydrate polymers should also generate large amounts of lignin with the potential for value addition. These developments have brought about renewed interest in the last decade for lignin and its potential use in polymer materials. This review covers both the topics of the direct use of lignin in polymer applications, and of the chemical modifications of lignin, in a polymer chemistry perspective. The future trend toward micro- and nanostructured lignin-based materials is then addressed.

  • 189.
    Dånmark, Staffan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polyester scaffold: Material design and cell-protein-material interaction2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tissue engineering has emerged as a valid approach for the regeneration and restoration of bone defects. The concept of bone tissue engineering includes degradable scaffolds, osteogenic cells and osteoinductive growth factors either alone or in any combination of these three. The scaffold bulk material and its design, in particular, are essential for reaching clinically relevant treatments. It is essential that the scaffold is biocompatible and acts as a temporary extra-cellular matrix with a porous 3-dimensional structure, supporting adhesion, proliferation and differentiation of osteogenic cells. Yet another criterion of the scaffold is that is must have sufficient mechanical stability to maintain structural integrity and protect the cells with a gradual transfer of mechanical load to the developing tissue. At the same time, the scaffolds needs to be bioresorbable with a controllable degradation rate depending on its application and the rate of tissue regrowth.

    In this thesis, aliphatic polyester scaffolds have been modified and shown to be suitable for bone tissue engineering applications. In addition, a new microfluidic device for live imaging of cell behavior within porous 3-dimensional scaffolds has been developed.

              Highly porous and degradable aliphatic polyester scaffolds with varying pore sizes and interconnected pores were fabricated. The polyesters assayed were random co-polyesters poly(L-lactide-co-ε-caprolactone) [poly(LLA-co-CL)] and poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO] and the homopolymer poly(L-lactide) [poly(LLA)]. The inherently different polymers yielded scaffolds with a wide range of properties with respect to surface chemistry, thermal properties, mechanical stability and degradation rate.

    The polyester scaffolds were shown to support the increased proliferation of bone marrow-derived stromal cells (BMSC) as well as enhanced osteogenic differentiation, with increased levels of osteocalcin gene expression, which emphasized their potential to act as cells carriers in bone tissue engineering. The potential of poly(LLA-co-CL) scaffolds and common biomedical polyesters in bone tissue engineering was further enhanced by surface functionalization. This involved two different methods of immobilization of bone morphogenetic protein-2 (BMP-2), a potent bone-growth-inducing factor, to the assayed polyesters. The first method used BMP-2 immobilized to heparin functionalized polyesters, while the second method covalently bonded BMP-2 to grafted linker groups on polyesters. Both immobilization techniques retain the bioactivity of BMP-2, and growth-factor-modified polyesters showed an increasing expression of osteogenic genes and production of osteocalcin in osteoblasts-like cells as well as increased proliferation in the mouse cell line, C3H10T1/2.

    The rate of degradation of electron-beam-sterilized polyester scaffolds and the subsequent loss of mechanical stability were strongly dependent on the chemical, physical and macroscopic architecture of the samples. The degradation rate and loss of mechanical integrity were much greater in porous scaffolds with hydrophilic co-monomers. By incorporating hydrophobic co-monomers with a limited ability to crystalize instead of hydrophilic co-monomers, the mechanical stability was retained for a longer time during the degradation process.

    The polyester supported spreading and flattened the morphology of both BMSC and osteoblast-like cells. The early cell adhesion to synthetic surfaces is mainly governed by the proteins adsorbed from its surrounding fluids. Early adhesion of BMSC to blood-plasma-coated polyesters was limited, despite the ability of the polyesters to adsorb adhesive proteins and expression of appropriate integrins on BMSC. However, adhesion to a purified adhesive matrix protein on the polyesters did occur, suggesting that pretreatment of polyester scaffolds with adhesive proteins or peptides is a feasible way to enhance the efficiency of cell loading into polyester scaffolds. 

                           Polyester scaffolds were combined with microfluidics and soft lithography to develop a new method for high-resolution imaging of live cells within porous scaffolds. The microfluidic device was used to frequently follow live cell proliferation and differentiation on the same spatial location within 3-dimansional porous scaffolds over a period of more than four weeks. This device is attractive for the evaluation of cells and materials intended for tissue engineering.

    We conclude that degradable aliphatic co-polyester scaffolds carefully designed with respect to macroscopic structure, bulk material and surface chemistry are able to meet the specific requirements of various bone tissue engineering applications. In addition, microfluidic devices permit reoccurring high resolution imaging of live cells within porous scaffolds and have a potential as a method of evaluating tissue engineering constructs.

  • 190.
    Dånmark, Staffan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Schander, K.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Arvidson, K.
    Mustafa, K.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    In vitro and in vivo degradation profile of aliphatic polyesters subjected to electron beam sterilization2011In: ACTA BIOMATERIALIA, ISSN 1742-7061, Vol. 7, no 5, p. 2035-2046Article in journal (Refereed)
    Abstract [en]

    Degradation characteristics in response to electron beam sterilization of designed and biodegradable aliphatic polyester scaffolds are relevant for clinically successful synthetic graft tissue regeneration Scaffold degradation in vitro and in vivo were documented and correlated to the macroscopic structure and chemical design of the original polymer The materials tested were of inherently diverse hydrophobicity and crystallinity poly(L-lactide) (poly(LLA)) and random copolymers from L-lactide and epsilon-caprolactone or 1.5-dioxepan-2-one, fabricated into porous and non-porous scaffolds After sterilization, the samples underwent hydrolysis in vitro for up to a year In vivo, scaffolds were surgically implanted into rat calvarial defects and retrieved for analysis after 28 and 91 days In vitro, poly(L-lactide-co-1, 5-dioxepan-2-one) (poly(LLA-co-DXO)) samples degraded most rapidly during hydrolysis, due to the pronounced chain-shortening reaction caused by the sterilization. This was indicated by the rapid decrease in both mass and molecular weight of poly(LLA-co-DXO). Poly(L-lactide-co-epsilon-caprolactone) (poly(LLA-co-CL)) samples were also strongly affected by sterilization, but mass loss was more gradual; molecular weight decreased rapidly during hydrolysis Least affected by sterilization were the poly(LLA) samples, which subsequently showed low mass loss rate and molecular weight decrease during hydrolysis. Mechanical stability varied greatly. poly(LLA-co-CL) withstood mechanical testing for up to 182 days, while poly(LLA) and poly(LLA-co-DXO) samples quickly became too brittle Poly(LLA-co-DXO) samples unexpectedly degraded more rapidly in vitro than in vivo. After sterilization by electron beam irradiation, the three biodegradable polymers present widely diverse degradation profiles, both in vitro and in vivo. Each exhibits the potential to be tailored to meet diverse clinical tissue engineering requirements

  • 191. Edberg, Jesper
    et al.
    Malti, Abdellah
    Granberg, Hjalmar
    Hamedi, Mahiar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Crispin, Xavier
    Engquist, Isak
    Berggren, Magnus
    Electrochemical circuits from 'cut and stick' PEDOT: PSS-nanocellulose composite2017In: Flexible and Printed Electronics, ISSN 2058-8585, Vol. 2, no 4, article id 045010Article in journal (Refereed)
    Abstract [en]

    We report a flexible self-standing adhesive composite made from PEDOT:PSS and nanofibrillated cellulose. The material exhibits good combined mechanical and electrical characteristics (an elastic modulus of 4.4 MPa, and an electrical conductivity of 30 S cm(-1)). The inherent self-adhesiveness of the material enables it to be laminated and delaminated repeatedly to form and reconfigure devices and circuits. This modular property opens the door for a plethora of applications where reconfigurability and ease-of-manufacturing are of prime importance. We also demonstrate a paper composite with ionic conductivity and combine the two materials to construct electrochemical devices, namely transistors, capacitors and diodes with high values of transconductance, charge storage capacity and current rectification. We have further used these devices to construct digital circuits such as NOT, NAND and NORlogic.

  • 192.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    A controlled radical polymerization route to polyepoxidated grafted hemicellulose materials2014In: Polimery, ISSN 0032-2725, Vol. 59, no 1, p. 60-65Article in journal (Refereed)
    Abstract [en]

    Polyfunctional copolymers were prepared from the major softwood hemicellulose polysaccharide, i.e. O-acetylated galactoglucomannan (AcGGM) through a grafting-from controlled radical polymerization. AcGGM was functionalized with brominated pendant groups that served as initiating species in the subsequent Cu(0) mediated radical polymerization of glycidyl methacrylate (GMA). A linear relationship of ln[GMA](0)/[GMA] (the index 0 refers to the initial value) versus reaction time up to conversions of 80 % suggests a first order rate of propagation and a "living" polymerization.

  • 193.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sauter, Tilman
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Covalent VEGF protein immobilization on resorbable polymeric surfaces2011In: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 22, no 12, p. 2368-2373Article in journal (Refereed)
    Abstract [en]

    Vascular endothelial growth factor type protein (VEGF), a potent angiogenic effector molecule, was successfully covalently immobilized onto the surfaces of the resorbable polymers poly(L-lactic acid) (PLLA) and poly(epsilon-caprolactone) (PCL) through a three-step strategy. The surfaces were first covalently grafted with poly(acrylic acid) using non-destructive and solvent free vapor-phase grafting. A diamine spacer was coupled to the carboxylic acid pendant groups on the graft chains using EDC/NHS chemistry and VEGF was finally covalently attached to the amine linkers. The chemistry and topography of the modified substrates were quantitatively and qualitatively verified with XPS, ATR-FTIR, UV-VIS, SEM, and ELISA.

  • 194.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Svensson, Marie
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Microsphere valorization of forestry derived hydrolysates2012In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 48, no 2, p. 372-383Article in journal (Refereed)
    Abstract [en]

    A value-adding approach to the material utilization of non-cellulosic polysaccharides (NCPs) released from the lignocellulosic feedstock was realized via the formulation of renewable microspheres from wood hydrolysates using a purposely elaborated all edible water-in-oil emulsion technique. Four compositionally different hemicellulose rich wood hydrolysates were recovered from process waters in pulping and other hydrothermal treatments of hardwood and softwood. Multivariate screening designs were employed allowing for the identification and quantitation of significant process parameters and interaction effects governing the conversion of hydrolysates into small, smooth and well-defined microspheres with narrow size dispersity.

  • 195.
    Ejdeholm, Daniel
    KTH, School of Chemical Science and Engineering (CHE).
    Mechanical Properties of Corroded Polypropylene2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To improve the service reliability of polymeric materials used in pickling environments the aim for this research project was to investigate how the corrosion of PP, exposed to mixed acid, changes its mechanical properties. It was found that PPH-β and PPB has a better resistance to the mixed acid environment both in the corrosion rate and impact strength compared to PPH-α and PPR. Further investigation showed that the penetration depth of the nitration is equal in the material exposed to only nitric acid. A useful method has been developed that can, in a relative short time period, give answers to the selected material´s adequacy for this specific environment. Materials that were tested were in the form of commercially available pipes. The samples were exposed to mixed acid from the inside for 7-27 days at temperatures of 60°C and 80°C. The corrosion rates were determined by pH-indicator and FTIR line-scans. The results were compared to pipes that had been in service for 2 years. The impact strength was determined by Charpy impact testing both on the inside and outside of the pipe walls. No changes in impact properties were found from impacts made to the inside of the pipe.

  • 196.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose, cellulose regenerates and derivatives2009Conference paper (Refereed)
  • 197.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Delignification and bleaching of the future pulp mill2002Conference paper (Refereed)
  • 198.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    New Cell. Innovative Biopolymers2006Conference paper (Refereed)
  • 199.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    New Cellulose Derivatives from Wood for High Value Products2007Conference paper (Refereed)
  • 200.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The Pulp Mill biorefinery2006Conference paper (Refereed)
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