Date of Award
Master of Science
Paper Engineering, Chemical Engineering and Imaging
Dr. Brian Scheller
Dr. Raja Aravamuthan
Masters Thesis-Open Access
Coating water loss is one of the most critical concerns in coated paper production. The objective of this study was to determine directly the water retention value under dynamic conditions. The effect of shear rate on water transfer was documented for a delaminated clay coating color. The results showed a small change in water transfer at low shear rates, compared to the static condition. But at higher shear rate, the water transfer increased significantly. The water transfer increased with time, reaching an asymptotic limit at 300 seconds. This indicates that at higher retention time, the water transfer rate is reduced due to plugging of the pores and filtercake formation.
The effect of pigment aspect ratio on water retention value of the coating color was also studied. The water transfer from a large aspect ratio clay was found to remain constant as shear rates increased. This may be due to alignment of particles. The water retention of a low aspect ratio clay decreased as shear rate increased. This may be due to filter cake breakup. The method demonstrates the effect of shear on the water retention of coatings and has great potential as a laboratory test for coating formulations.
Thiagarajan, Mohana Sundaram, "Direct Measurement of the Water Retention of Coatings Under Shear" (1998). Masters Theses. 5318.