Browsing by Author "Ihalainen, Petri"

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On Laccase-Catalyzed Polymerization of Biorefinery Lignin Fractions and Alignment of Lignin Nanoparticles on the Nanocellulose Surface via One-Pot Water-Phase Synthesis
(2021-07-05) Wang, Luyao; Tan, Liping; Hu, Liqiu; Wang, Xiaoju; Koppolu, Rajesh; Tirri, Teija; van Bochove, Bas; Ihalainen, Petri; Sobhana Seleenmary Sobhanadhas, Liji; Seppälä, Jukka V.; Willför, Stefan; Toivakka, Martti; Xu, Chunlin
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Two series of well-defined lignin fractions derived from birch and spruce alkaline lignin (AL) by sequential solvent fractionation (i-PrOH-EtOH-MeOH) were engaged in a structure–property-application relationship study. The bacterial-derived alkaliphilic laccase (MetZyme) extensively catalyzed the oxidation and polymerization of AL fractions in an aqueous alkaline solution (pH 10). Lignin fractions with low molar mass reached a higher polymerization degree due to more phenolic-OH groups serving as reactive sites of oxidation and better lignin-laccase accessibility arose from a lower lignin condensation degree than the high molar mass ones. In comparison, AL fractions from spruce were found to be less reactive toward the laccase-catalyzed polymerization than those from birch, which was attributed to the much pronounced aryl-vinyl moieties’ oxidation. Furthermore, in situ polymerization of birch AL fractions using microfibrillated cellulose as a structural template was conducted in an aqueous medium and a dispersion of nanocellulose with its fiber network evenly coated by aligned lignin nanoparticles was obtained. The present study not only provides fundamental insights on the laccase-assisted oxidation and polymerization of lignin but also presents a new perspective for valorizing lignin in biobased fiber products through green processing of solvent fractionation and enzymatic treatment.
Paalutettu Kopler-teräsverkkopenger
(2009) Ihalainen, Petri
School of Engineering | Master's thesis
The piled steelgrid embankment is best suited for soil reinforcement of consolidating yards, where we can get the most use of its competitivity. Yards that consolidate are a national and an economical problem. Soil settlement generates large additions to use and repair costs. Well made surface strutures are ruined if the soil consolidates. There is a need for developing new soil construction methods. The soil reinforcement of large yards is quite expensive so more and more attention will progressively be used for soil construction in the near future. In Finland, Steelgrids are being used under highways to equalize soil consolidations, but they haven´t been directly used as a georeinforcement with the piled embankment. In this master´s thesis we analyse the use of steelgrid as a soil reinforcement method for a piled embankment. The thesis includes the steps of development, the measurement of the reinforcement method, the risk control of the method and the analysis of the experimental structure. The experimental structure that was built in association with the thesis is located in Vanttila, Espoo and it is used as a parking area for a local school. The structure was instrumentated and these results are analysed in this thesis. We found out that the structure is working mechanically. Advantages for this method are a short building time and low consolidation. Disadvantages should include poor repairbility under the steelgrid. The optimization of the method is not finished.