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- Thorman, Sofia, et al.
(författare)
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Uniformity of liquid absorption by coatings : Technique and impact of coating composition
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 456-465
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between a liquid and a paper surface is important for a number of paper treatment processes, where absorption is of special significance during printing. Many absorption measurement techniques use a large available volume of liquid to characterise absorption, when compared to the volume of the coating. The uniformity of the absorption is also seldom characterised. We have developed a new technique, which is presented in this article, to study the uniformity of absorption of a small amount of liquid. This technique is based on the short-time absorption (tenth of a second) of a coloured liquid, the blotting of excess liquid and a characterisation of the pattern of the stain. This method made it possible to detect differences among coating layers with different compositions. In many cases, the absorption non-uniformity could be linked to variations in the coating thickness and/or wettability. The thinner and thicker areas of the coating layers were interpreted as having different pore structures. Neither the coating thickness nor the wettability could provide a full explanation, which showed the need to develop a method to characterise absorption uniformity instead of only relying on measuring the total absorption potential.
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