The study of the liquid spreading on the paper surface is of great importance in the printing industry, specifically for inkjet printing, and for barriers applied on packaging paper. The liquid spreading and the determination of contact angle are correlated, so the paper surface energy can be calculated. However the paper roughness influences the spreading of liquid drops and the Wenzel and Cassie equations are respectively the most used ones for the correction of contact angle based on previous information on surface roughness and heterogeneity. In this study, five types of paper were analyzed using traditional methods and profilometric roughness evaluation method. The evolution of contact angle and water drop radius over time was monitored. The impact of macroroughness is mainly due to the formation of air pockets on the surface and the microroughness affects with the pinning effect on the influence the contact angle and spreading of the water drop. Therefore, the roughness evaluation method shall be able to describe the multi-scale nature of paper surface.
YASUMURA, Patrícia Kaji; PARK, Song Won. Comparison of methods for paper roughness and porosity assessment. In: ABTCP INTERNATIONAL PULP AND PAPER CONGRESS, 45.,e IBEROAMERICAN CONGRESS ON PULP AND PAPER RESEARCH, 7., 2012, São Paulo. Proceedings… 9 p.
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