| 1. |
- Haapanen, Janne, et al.
(författare)
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Binary TiO2/SiO2 nanoparticle coating for controlling the wetting properties of paperboard
- 2015
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 149, s. 230-237
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a flame based aerosol method to fabricate thin films consisting of binary TiO2/SiO2 nanoparticles deposited directly from the flame onto the paperboard. Nanocoatings were prepared with Liquid Flame Spray (LFS) in a roll-to-roll process with the line speed of 50 m/min. Surface wetting behavior of nanocoated paperboard was studied for different Ti/Si ratios in the precursor, affecting TiO2/SiO2 ratio in the coating. Wettability could be adjusted to practically any water contact angle between 10 and 160° by setting the Ti/Si ratio in the liquid precursor. Structure of the two component nanocoating was analysed with FE-SEM, TEM, EDS, XPS and XRD. The porous thin film coating was concluded to consist of ca. 10 nm sized mixed oxide nanoparticles with segregated TiO2 and SiO2 phases. Accumulation of carbonaceous compounds on the surface was seen to be almost linearly dependent on the Ti/Si ratio, indicating of each species being exposed in corresponding amount. However, wetting of the surface was observed to follow merely an S-shaped curve, caused by the roughness of the nanocoated surface. Reasons for the observed superhydrophobicity and superhydrophilicity of these binary nanocoatings on paperboard are discussed.
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| 2. |
- Aromaa, Mikko, et al.
(författare)
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Atmospheric synthesis of superhydrophobic TiO2 nanoparticle deposits in a single step using Liquid Flame Spray
- 2012
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 52, s. 57-68
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Tidskriftsartikel (refereegranskat)abstract
- Titanium dioxide nanoparticles are synthesised in aerosol phase using the Liquid Flame Spray method. The particles are deposited in-situ on paperboard, glass and metal surfaces. According to literature, titanium dioxide is supposed to be hydrophilic. However, hydrophobic behaviour is observed on paperboard substrates but not on metal or glass substrates. Here, the water contact angle behaviour of the deposits is studied along with XRD, XPS, BET and HR-TEM. The deposits are compared with silicon dioxide deposits having, as expected, hydrophilic properties synthesised with the same method. It seems probable that the deposition process combusts some substrate material from the paperboard substrate, which later on condenses on top of the deposit to form a carbonaceous layer causing the hydrophobic behaviour of the TiO2 deposit. The similar layer does not form when depositing the nanoparticles on a metal or glass surfaces. The observations are more than purely aerosol phenomena. However, they are quite essential in nanoparticle deposition from the aerosol phase onto a substrate which is commonly utilised. (C) 2012 Elsevier Ltd. All rights reserved.
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| 3. |
- Haapanen, Janne, et al.
(författare)
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On the limit of superhydrophobicity : Defining the minimum amount of TiO2 nanoparticle coating
- 2019
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Ingår i: Materials Research Express. - : IOP Publishing. - 2053-1591. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication of superhydrophobic surfaces in large scale has been in high interest for several years, also titanium oxide nanostructures having been applied for the purpose. Optimizing the amount and structure of the TiO2 material in the coating will play a key role when considering upscaling. Here, we take a look at fabricating the superhydrophobic surface in a one-step roll-to-roll pilot scale process by depositing TiO2 nanoparticles from a Liquid Flame Spray onto a moving paperboard substrate. In order to find the minimum amount of nanomaterial still sufficient for creating superhydrophobicity, we varied nanoparticle production rate, flame distance from the substrate and line speed. Since the deposited amount of material sideways from the flame path was seen to decrease gradually, spatial analysis enabled us to consistently determine the minimum amount of TiO2 nanoparticles on the substrate needed to achieve superhydrophobicity. Amount as low as 20-30 mg m-2 of TiO2 nanoparticles was observed to be sufficient. The scanning electron microscopy revealed that at this amount, the surface was covered with nanoparticles only partially, but still sufficiently to create a hierarchical structure to affect wetting significantly. Based on XPS analysis, it became apparent that TiO2 gathers hydrocarbons on the surface to develop the surface chemistry towards hydrophobic, but below the critical amount of TiO2 nanoparticles, the chemistry could not enable superhydrophobicity anymore. While varying the deposited amount of TiO2, besides the local spatial variance of the coating amount, also the overall yield was studied. Within the text matrix, a yield up to 44% was achieved. In conclusion, superhydrophobicity was achieved at all tested line speeds (50 to 300 m min-1), even if the amount of TiO2 varied significantly (20 to 230 mg m-2).
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| 4. |
- Stepien, Milena, et al.
(författare)
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Surface characterization of nanoparticle coated paperboard
- 2012
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Ingår i: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012. - 9781466562745 ; , s. 710-713
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Konferensbidrag (refereegranskat)abstract
- Both surface topographical and chemical composition of nanoparticle coated paperboard was characterized to explain observed differences in surface wettability. TiO 2 particles induce superhydrophobicity with water contact angle (CA) of 161° whereas SiO 2 particles result in superhydrophilicity with 23° water CA. The nanoparticles were generated by the liquid flame spray (LFS) process. The morphological characterization of reference paperboard and nanocoated samples was performed using FESEM and AFM. Both XPS and CA measurements were used to evaluate chemical composition before and after nanoparticle deposition. Our results show that the LFS process can be used to create either hydrophobic or hydrophilic paperboard depending on the type of nanoparticles used for coating. The wettability differences were contributed to the attributed effect of surface chemistry and topography.
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| 5. |
- Stepien, Milena, et al.
(författare)
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Wear resistance of nanoparticle coatings on paperboard
- 2013
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Ingår i: Wear. - 0043-1648 .- 1873-2577. ; 307:1-2, s. 112-118
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Tidskriftsartikel (refereegranskat)abstract
- Paper can be coated with liquid flame spray (LFS) generated nanoparticles to control the wettability of its surface from hydrophilic to superhydrophobic. The adhesion of the nanoparticles on paper is of interest both for understanding the product durability during its lifetime and for product safety issues. Poor particle adhesion influences the desired functional properties and released nanoparticles cause health and environmental concerns. To investigate the wear resistance of LFS-TiO2 and -SiO2 coated papers, the nanoparticle surfaces were exposed to rotary abrasion tests. The changes in the samples were analyzed by contact angle measurements and high resolution field-emission scanning electron microscopy (FESEM). After abrasive action with another paperboard surface, only relatively small changes in wettability of superhydrophobic/hydrophilic coatings were found. A more severe abrasive action will remove some of the nanoparticle coating, but the hydrophobic/hydrophilic character of the surface is still maintained to large extent. The results indicate that the wear resistance of LFS nanocoated paper surfaces differs and depends on the nanoparticle material type used for the coating. This is clearly reflected as changes in surface structure shown by FE-SEM and wettability. The results can help understanding which paper-related application areas could be targeted with the LFS-nanoparticle coating process.
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| 6. |
- Stepien, Milena, et al.
(författare)
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Wear resistance of nanoparticle coatings on paperboard
- 2013
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Ingår i: TAPPI International Conference on Nanotechnology 2013. - : TAPPI Press. - 9781510815681 ; , s. 821-829
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Konferensbidrag (refereegranskat)abstract
- • LFS-deposited TiO2 and SiO2 nanoparticles create superhydro-phobic and hydrophilic paper surface, • Abrasive damage of surface structure influences only slightly the wettability of superhydrophobic TiO2 and hydrophilic SiO2 coatings, • A more severe abrasive action will remove some of the nanoparticle coating, but the hydrophobic/hydrophilic properties of the surface are maintained, • SiO2 nanoparticle coated surface is more resistant to abrasion than the TiO2 coating, which indicates a stronger inter-particle and particle to surface adhesion of the former, • Investigation of nanoparticle loss from the paper surface is challenging, due to the small total mass of nanoparticles in the coating, mixed together with pigment particles and fiber debris removed during abrasion experiment.
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| 7. |
- Tuominen, Mikko, et al.
(författare)
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Adjustable wetting of liquid flame spray (LFS) TiO2-nanoparticle coated board : Batch-type versus roll-to-roll stimulation methods
- 2014
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Ingår i: Nordic Pulp & Paper Research Journal. - : SPCI. - 0283-2631 .- 2000-0669. ; 29:2, s. 271-279
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Tidskriftsartikel (refereegranskat)abstract
- Superhydrophobic nanoparticle coating was created on the surface of board using liquid flame spray (LFS). The LFS coating was carried out continuously in ambient conditions without any additional hydrophobization steps. The contact angle of water (CAW) of ZrO2, Al2O3 and TiO2 coating was adjusted reversibly from >150° down to ~10-20° using different stimulation methods. From industrial point of view, the controlled surface wetting has been in focus for a long time because it defines the liquid-solid contact area, and furthermore can enhance the mechanical and chemical bonding on the interface between the liquid and the solid. The used stimulation methods included batch-type methods: artificial daylight illumination and heat treatment and roll-to-roll methods: corona, argon plasma, IR (infra red)- and UV (ultra violet)-treatments. On the contrary to batch-type methods, the adjustment and switching of wetting was done only in seconds or fraction of seconds using roll-to-roll stimulation methods. This is significant in the converting processes of board since they are usually continuous, high volume operations. In addition, the creation of microfluidic patterns on the surface of TiO2 coated board using simple photomasking and surface stimulation was demonstrated. This provides new advantages and possibilities, especially in the field of intelligent printing. Limited durability and poor repellency against low surface tension liquids are presently the main limitations of LFS coatings.
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| 8. |
- Brobbey, Kofi, et al.
(författare)
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High-speed production of antibacterial fabrics using liquid flame spray
- 2019
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Ingår i: Textile research journal. - : SAGE Publications Ltd. - 0040-5175 .- 1746-7748. ; 90:5-6, s. 503-511
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Tidskriftsartikel (refereegranskat)abstract
- Healthcare associated infections (HAIs) are known as one of the major problems of the modern healthcare system, which result in additional cost and mortality. It has also been shown that pathogenic bacteria are mostly transferred via surfaces in healthcare settings. Therefore, antibacterial surfaces, which include fabrics and textiles, can be used in a healthcare environment to reduce the transfer of pathogenic bacteria, hence reducing HAIs. Silver nanoparticles have been shown to have broad spectrum antibacterial properties, and therefore they have been incorporated into fabrics to provide antibacterial functionality. Liquid flame spray (LFS) nanoparticle synthesis allows nanoparticles to be produced and deposited on surfaces at speeds up to and beyond 300 m/min. Herein, LFS is used to deposit silver nanoparticles onto two fabrics that are commonly used in the hospital environment with the aim of producing antibacterial fabrics. A thin plasma coating on top of the fabrics after silver deposition is used to improve nanoparticle adhesion. Fabrics coated with silver nanoparticles demonstrated antibacterial properties against Escherichia coli. Nanoparticle imaging and surface chemical characterization are performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The highlights of this research are as follows: • high-speed synthesis and deposition of silver nanoparticles on fabrics; • plasma coating onto fabrics with silver nanoparticles; • antibacterial fabrics for potential use in healthcare environments.
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| 9. |
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| 10. |
- Drobac, Senka, et al.
(författare)
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The Labourious Cleaning : Acquiring and Transforming 19th-Century Epistolary Metadata
- 2023
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Ingår i: DHNB2023 Conference Proceedings. - Oslo.
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Konferensbidrag (refereegranskat)abstract
- The paper documents the process of collecting, consolidating, and publishing epistolary metadata from Finnish cultural heritage organizations to create an archive for bottom-up analyses of 19th-century epistolary culture. We describe and discuss the data survey that was conducted to gather information about available letter collections across Finland, as well as the cleaning and harmonizing of over 350,000 letters from twelve different sources in various digital formats. We have also developed a data model that combines event-based and letter-based aspects of the metadata. Furthermore, the paper contributes tothe ongoing discussion of the initial phases of data-intensive research and the importance of discussing the labor of cleaning data. We believe that our experiences described in this paper can have wider significance for other digital humanities projects in Europe.
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