Measurement of paper-wetting processes by ultrasound transmission

Abstract

Understanding of wetting processes for papers of various qualities is important for the analysis and the adjustment of paper-production processes as well as for designing properties of paper for printing. In this investigation, papers of one kind with three different sizing-content values were examined by time-dependent attenuation of ultrasound transmission in mixtures of isopropanol and water. The attenuation depends on the stage of absorption of liquid into the paper sample, which furnishes the signature of the paper type and quality. Papers that have contact angles of 40° (without size), 70° (low size content) and 110° (high size content) were tested and a measurement procedure was developed. The measurement results showed that the development of attenuation with time differs at different frequencies, indicating the possibility of detecting various phases of wetting phenomena.

Hydrophobization and Antimicrobial Activity of Chitosan and Paper-Based Packaging Material

“…Ultrasound waves are transmitted through water with different intensity losses depending on the crossed material (water, air, occurrence of paper fibers occasioning diffusion, etc. ). – PDA curves plot the percentage of transmission of the ultrasonic signals versus time. Transmission is set at 100% at maximum of each curve, the time corresponding to the maximum of each curve is defined as the “wetting time” of the material, and the slope of the curve after this maximum is proportional to the speed of penetration of water through the material.…”

Measuring paper wetting processes with laser transmission

“…In our earlier work [7,18,19], we studied paper wetting by ultrasonic transmission measurements. In the first study, the sample was immersed into a water tank between two ultrasonic transducers after which the received ultrasonic pressure amplitude was recorded.…”

Ultrasonic Liquid Penetration Measurement in Thin Sheets—Physical Mechanisms and Interpretation

“…Furthermore, mostly 1 and 2 MHz have been used to perform ULP measurements and these frequencies have proved to be suitable for paper. However, other measurement frequencies could potentially reveal events on different spatial scales [10] and might be needed for substrates other than paper (e.g., membranes, nanoporous films, etc.). In this context it is important to remember that the bubble size critical for resonance also depends on the frequency of the ultrasound signal.…”

“…Since then, ultrasonic liquid penetration (ULP) measurements have been applied to study different aspects of interactions between liquids and porous, sheet like materials (paper, membranes, and thin films). Things investigated were for example network hydrophobization (sizing) [3][4][5][6], kinetics of liquid absorption (wetting and penetration) [7][8][9][10], evaluating water/grease barrier properties [11][12][13][14], as well as predicting print quality [15][16][17][18] and gluing strength [19]. The method has even been used to characterize the structure of the paper substrate, e.g., surface pores and roughness [20][21][22][23].…”