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21.
Miia Hiltunen Simon Riihelä Sirkka Liisa Maunu 《Journal of Polymer Science.Polymer Physics》2009,47(19):1869-1879
The syntheses and rheological behavior of ethyl hydroxyethyl cellulose (EHEC)‐based graft‐copolymers were studied. Copolymers were prepared by grafting EHEC with acrylamide (Aam) via reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyl groups of EHEC were esterified with a carboxylic acid functional chain transfer agent (CTA) to prepare EHEC‐macroCTAs with different degrees of substitution. EHEC‐macroCTAs were characterized by ATR‐FTIR, 13C NMR, and SEC, and elemental analysis was used to quantify the degree of CTA substitution. EHEC‐macroCTAs with different degrees of substitution were copolymerized with acrylamide by “grafting from” technique. Formation of new cellulose‐based copolymers was comprehensively confirmed by 1H NMR, ATR‐FTIR, and SEC measurements. Further, the associations of EHEC‐g‐PAam copolymers in water were studied at various concentrations and temperatures by means of UV–vis spectroscopy, fluorescence spectroscopy, and rheological measurements. The results indicate that copolymers have both intra and intermolecular association in water depending on the amount of grafts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1869–1879, 2009 相似文献
22.
Pirita Uschanov Leena-Sisko Johansson Sirkka Liisa Maunu Janne Laine 《Cellulose (London, England)》2011,18(2):393-404
Heterogeneous modification of various types of cellulose (microcrystalline cellulose, cellulose whiskers and regenerated cellulose)
was performed with long-chain fatty acids by an esterification reaction. The differences in reactivity between the celluloses
were studied as well as the influences of the chain length and double bond content of the fatty acids. The success of the
modification reaction and the structure of modified samples were studied with diverse characterization methods. Surface modification
changed the thermal stability of cellulose by decreasing the degradation temperature but also made the pyrolysis curve two-stepped
due to the double bonds in the fatty acid chain. It was observed that the nature of the fatty acid affected the degree of
substitution (DS). The longer the fatty acid chain was, the lower was the DS. Fatty acids with increased double bond content
gave decreased DS. Regenerated cellulose seemed to have the highest surface reactivity due to the distinct morphological structure,
which also led to a much lower quantity of fatty acids attached to the structure than for other modified cellulose particles.
The mixture of tall oil fatty acids behaved in the same manner as the commercial fatty acids, proving to be an excellent “green”
choice for this kind of application. 相似文献
23.
Miia Hiltunen Joonas Siirilä Vladimir Aseyev Sirkka Liisa Maunu 《European Polymer Journal》2012,48(1):136-145
Water-soluble cellulose-graft-PDMAam copolymers were prepared by single-electron-transfer living radical polymerization (SET-LRP). Cellulose based macroinitiator for SET-LRP with a degree of substitution DS ≈ 2 was synthesized from softwood dissolving pulp in a homogeneous LiCl/DMAc solution. The macroinitiator was then grafted using N,N-dimethyl acrylamide (DMAam) in DMSO. Formation of cellulose-g-DMAam copolymers were confirmed by ATR–FTIR, 1H and 13C NMR spectroscopy and SEC analyses. Light scattering and steady–shear viscosity measurements revealed that the studied chain length of grafts (DPgraft) had only minor effects on the solution properties of cellulose-g-PDMAam copolymers. SLS studies suggested a loose, solvent-draining architecture of the cellulose-g-PDMAam copolymer particles in H2O. 相似文献
24.
Sami Hietala Sirkka Liisa Maunu Franciska Sundholm 《Journal of Polymer Science.Polymer Physics》2000,38(24):3277-3284
Sorption and diffusion properties of poly(vinylidene fluoride)‐graft‐poly(styrene sulfonic acid) (PVDF‐g‐PSSA) and Nafion® 117 polymer electrolyte membranes were studied in water/methanol mixtures. The two types of membranes were found to have different sorption properties. The Nafion 117 membrane was found to have a maximum in‐solvent uptake around 0.4 to 0.6 mole fraction of methanol, while the PVDF‐g‐PSSA membranes took up less solvent with increasing methanol concentration. The proton NMR spectra were recorded for membranes immersed in deuterated water/methanol mixtures. The spectra showed that the hydroxyl protons inside the membrane exhibit resonance lines different from the resonance lines of hydroxyl protons in the external solvent. The spectral features of the lines of these internal hydroxyl groups in the membranes were different in the Nafion membrane compared with the PVDF‐g‐PSSA membranes. Diffusion measurements with the pulsed field gradient NMR (PFG‐NMR) method showed that the diffusion coefficient of the internal hydroxyl groups in the solvent immersed Nafion membrane mirrors the changes in the diffusion coefficients of hydroxyl and methyl protons in the external solvent. For the PVDF‐g‐PSSA membranes, a decrease in the diffusion coefficient of the internal hydroxyl protons was seen with increasing methanol concentration. These results indicate that the morphology and chemical structure of the membranes have an effect on their solvent sorption and diffusion characteristics. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3277–3284, 2000 相似文献
25.
Carl-Mikael Tåg Maunu Toiviainen Cathy Ridgway Mikko Juuti Patrick A. C. Gane 《Transport in Porous Media》2013,99(1):145-160
The rate of absorption (both long and short timescale) of typical heatset offset printing ink oils, namely mineral and linseed oil, has been studied on model ground calcium carbonate coating pigment tablets containing various amounts of either styrene–acrylic or styrene–butadiene binder. The pore structure characteristics of the tablets were determined using mercury intrusion porosimetry. The movement of the oils both on the surface of and within the porous structure of the pigment/binder tablets was studied under the influence of pressure-less capillary flow with subsequent diffusion through the connected void volume of the tablet. The wetting was analyzed by near-infrared (NIR) diffuse reflectance spectroscopy both as a single probe measurement and by hyperspectral imaging. The results showed that the rate of oil filling the structure was strongly dependent on the binder amount in the structure as well as the binder chemistry (oil- or non-absorbing binder), which supports previous findings. The liquid properties, and especially the viscosity of the liquid (oil), influenced the absorption rate. The gradients in absorbance indicated the presence of latex blocking access to some pores and reducing connectivity. 相似文献
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27.
Tommi Virtanen Kirsi Svedström Seppo Andersson Laura Tervala Mika Torkkeli Matti Knaapila Nina Kotelnikova Sirkka Liisa Maunu Ritva Serimaa 《Cellulose (London, England)》2012,19(1):219-235
A detailed physico-chemical characterisation of potential new cellulose sources (rice husk, hemp stalk, and coniferous needles),
and microcrystalline cellulose (MCC) manufactured from them, was made in this work. The length and the width of the cellulose
crystallites were determined by wide-angle X-ray scattering (WAXS), crystallinities were studied by means of WAXS and solid
state cross polarisation magic angle spinning 13C nuclear magnetic resonance (NMR) spectroscopy, and the packing and the cross-sectional shape of the microfibrils were determined
by small-angle X-ray scattering. When MCC was prepared from rice husks and hemp stalks an acceptable yield was obtained. Crystallinities
obtained with solid state NMR spectroscopy and WAXS were highest for MCC prepared from hemp stalks, and lowest for rice husk
MCC. The crystallite sizes of MCC samples studied in this work varied more than in those MCC samples which were prepared from
conventional plant sources, and crystallite size and cellulose crystallinity were related. When taking into account rather
high values of specific surface, hemp stalks and rice husks appear as a promising raw materials for MCC production. 相似文献
28.
Sirkka Maunu Tiina Liitiä Seppo Kauliomäki BO HORTLING JORMA SUNDQUIST 《Cellulose (London, England)》2000,7(2):147-159
In order to obtain information about the crystallinity and polymorphs of cellulose, and the occurrence of hemicelluloses in pulp fibers, wood cellulose, bacterial cellulose, cotton linters, viscose, and celluloses in different pulps were investigated by solid state 13C CPMAS NMR spectroscopy. A mixed softwood kraft pulp and a dissolving-grade pulp were treated under strongly alkaline and acidic conditions and the effect on cellulose crystallinity was studied. The presence of different crystalline polymorphs of cellulose and the amounts of hemicelluloses are considered. 相似文献
29.
Sirkka-Liisa Jms-Jounela Sampsa Laine Eeva Ruokonen 《Particle & Particle Systems Characterization》1998,15(4):200-207
Artificial intelligence (AI) includes excellent tools for the control and supervision of industrial processes. Several thousand industrial applications have been reported worldwide. Recently, the designers of the AI systems have begun to hybridize the intelligent techniques, expert systems, fuzzy logic and neural networks, to enhance the capability of the AI systems. Expert systems have proved to be ideal candidates especially for the control of mineral processes. An expert system based on on-line classification of the ore type has been developed. Self-organizing maps (SOM) are used for pattern recognition of the type of feed. The system has been tested in two concentrators, the Outokumpu Finnmines Oy, Hitura Mine and Outokumpu Chrome Oy, Kemi Mine. The methodology for the development of the ore type based expert system is presented and the preliminary results obtained in the above plants are described. 相似文献