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Item type:Publication, Access status: with files , Spray coating of cellulose aerogel particles in a miniaturized spouted bed(Springer, 2021-07-04); ; ; ; Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.Publicationtype: Journal ArticleScopus© Citations 13 218 261 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Characterization of waxes as possible coating material for organic aerogels(2019-12-01); Aerogels require nontoxic coatings which are good barriers to the environment and do not affect the fragile porous network. There is a wide range of coating materials available for a variety of applications and functionalities. Waxes, for example, are good moisture barrier candidates and do not require additional solvents during processing. Hence, in this work four different natural waxes were tested concerning their application as coating material for porous aerogels. Therefore, beeswax, candelilla wax, rice bran wax and sunflower wax were investigated regarding their thermic properties, moisture barrier properties and wettability. Beeswax and rice wax proved favourable for coating aerogels. Beeswax shows low water vapour permeability, low minimum film forming temperature and forms continuous films. The water vapour permeability of rice wax is higher compared to beeswax, but there is no minimum film forming temperature in the temperature range of 20 °C–80 °C and the appearance of the rice wax films is homogeneous. Candelilla wax and sunflower wax are not suitable for coating of aerogels. Candelilla wax forms discontinuous films which diminish its water barrier properties. Sunflower wax has the highest water vapour permeability, forms porous films and forms cracks on the surface of the film during solidification below 62 °C.Publicationtype: Journal Article223