Hille Rautkoski

Structural and Nanomechanical Properties of Paperboard Coatings Studied by Peak Force Tapping Atomic Force Microscopy

Paper coating formulations containing starch, latex, and clay were applied to paperboard and have been investigated by scanning electron microscopy and Peak Force tapping atomic force microscopy. A special focus has been on the measurement of the variation of the surface topography and surface material properties with a nanometer scaled spatial resolution. The effects of coating composition and drying conditions were investigated. It is concluded that the air-coating interface of the coating is dominated by close-packed latex particles embedded in a starch matrix and that the spatial distribution of the different components in the coating can be identified due to their variation in material properties. Drying the coating at an elevated temperature compared to room temperature changes the surface morphology and the surface material properties due to partial film formation of latex. However, it is evident that the chosen elevated drying temperature and exposure time is insufficient to ensure complete film formation of the latex which in an end application will be needed.

Mechanically ground softwood fines as a raw material for cellulosic applications

Utilization of mechanically manufactured lignocellulosic fines (LCNFs) was investigated in making filaments and films. The LCNFs particles were prepared by using a mechanical grinding method with a w-profile grinding stone that produces mostly fines with dimensions in the micrometer scale. The chemical and elemental composition of the w-stone ground LCNFs particles was investigated. It was found that the mechanically manufactured material exhibited the chemical structure of native wood. The LCNFs particles had an anionic surface charge making them colloidally semi-stable in water. The short length of the fines particles prevents their effective mechanical entanglement, which sets some limitations on preparation of filaments and films. Filament manufacturing required the use of a composite approach with carboxymethyl cellulose (CMC) as a binder polymer. The filament was manufactured by using dry-jet wet spinning with aluminium sulfate crosslinking. The chemical composition, crosslinking mechanism, and mechanical properties of the composite filaments were investigated. The composite approach with CMC was also used to prepare composite films with good mechanical performance. The investigated LCNFs material could be utilized in all-lignocomposite applications with cellulose derivatives, where biodegradability and biobased characteristics are desired properties.

Atomic layer deposition of Ti-Nb-O thin films onto electrospun fibers for fibrous and tubular catalyst support structures

Here, the authors report on the preparation of core–shell carbon-ceramic fibrous as well as ceramic tubular catalyst supports utilizing electrospinning and atomic layer deposition (ALD). In this paper, ALD of Ti-Nb-O thin films using TiCl4, Nb(OEt)5, and H2O as precursors is demonstrated. According to the time-of-flight-elastic recoil detection analysis and Rutherford backscattering spectrometry, carbon and hydrogen impurities were relatively low, but depend on the pulsing ratio of the precursors. Optimized ALD process was used for coating of sacrificial electrospun polyvinyl alcohol (PVA) template fibers to yield tubular Ti-Nb-O structures after thermal or solution based PVA removal. Another approach utilized 200–400 nm thick carbon fibers prepared by electrospinning from polyacrylonitrile and subsequent thermal treatment.Here, the authors report on the preparation of core–shell carbon-ceramic fibrous as well as ceramic tubular catalyst supports utilizing electrospinning and atomic layer deposition (ALD). In this paper, ALD of Ti-Nb-O thin films using TiCl4, Nb(OEt)5, and H2O as precursors is demonstrated. According to the time-of-flight-elastic recoil detection analysis and Rutherford backscattering spectrometry, carbon and hydrogen impurities were relatively low, but depend on the pulsing ratio of the precursors. Optimized ALD process was used for coating of sacrificial electrospun polyvinyl alcohol (PVA) template fibers to yield tubular Ti-Nb-O structures after thermal or solution based PVA removal. Another approach utilized 200–400 nm thick carbon fibers prepared by electrospinning from polyacrylonitrile and subsequent thermal treatment.