Holman Richard K, Cima Michael J, Uhland Scott A, Sachs Emanuel
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Colloid Interface Sci. 2002 May 15;249(2):432-40. doi: 10.1006/jcis.2002.8225.
Simultaneous spreading and infiltration of inkjet-printed droplets has been studied. Small (54- and 63-microm diameter) droplets of an aqueous polymer solution (2.4 vol% polyacrylic acid, PAA, MW 60,000) were deposited on high green density porous ceramic beds, and the wetting-induced spreading and infiltration of the droplets were characterized. The time scales for spreading and infiltration were comparable (approximately milliseconds), resulting in interruption of the spreading prior to completion by infiltration of the liquid into the powder bed, a situation that has received little treatment in the literature. The infiltration time was varied by changing the pore size (via particle size) in the powder bed, and it was confirmed that slower infiltration resulted in greater spreading of the liquid. The spreading and infiltration of the droplet were modeled to examine the coupling between the two processes and allow prediction of the maximum extension of the droplet as a function of the powder bed particle size. The liquid spreading was found to follow r(t)=a(b+t)(n) behavior, and the effect of particle size on infiltration time was used to predict the point at which spreading ceases due to infiltration for various particle sizes.
已对喷墨打印液滴的同时铺展和渗透进行了研究。将一种聚合物水溶液（2.4体积%的聚丙烯酸，PAA，分子量60,000）的小液滴（直径54和63微米）沉积在高生坯密度的多孔陶瓷床上，并对液滴的润湿诱导铺展和渗透进行了表征。铺展和渗透的时间尺度相当（约为毫秒），导致在铺展完成之前，液体渗透到粉末床中，从而中断铺展，这种情况在文献中很少受到关注。通过改变粉末床的孔径（通过颗粒尺寸）来改变渗透时间，并且证实较慢的渗透会导致液体更大程度的铺展。对液滴的铺展和渗透进行建模，以研究这两个过程之间的耦合，并预测液滴的最大扩展程度作为粉末床颗粒尺寸的函数。发现液体铺展遵循r(t)=a(b+t)(n)行为，并且利用颗粒尺寸对渗透时间的影响来预测由于不同颗粒尺寸下的渗透而导致铺展停止的点。
