《Spontaneous absorption of droplets into single pores of different radii》.pptVIP

Spontaneous absorption of droplets into single pores of different radii” G. Callegari 1 A. Neimark 2 K. Kornev 3 TRI/Princeton, Princeton, NJ, 08540, USA Chem. Eng. Dept., Rutgers University, Piscataway, NJ, USA Sch. of Materials Sc., Clemson University, Clemson, SC, USA Outline Fast spontaneous absorption of droplets by capillaries Aplications: Droplet absorption/ spreading in porous materials Introduction Spreading/wetting and absorption of droplets in porous materials 1- Absorption/Dewetting 2- Pure Fast absorption thick, large pores, rough surface thin, small pores, smooth surface Inertial vs viscous effects Introduction of Dynamic Contact Angle Viscoelastic effects Droplet absorption/ spreading in porous materials: Applications Ink Jet Printing Micro-chromatography Granulation process Agglomeration of fine powders using liquids as binders Industrial processes: Agriculture chemistry Pharmaceutical Mineral processing Food Detergency Micro amounts of biological fluids for bio-components recognition Spray Painting of porous materials Absorption/Spreading of droplets into porous media They all considered only viscous forces Denesuk et al. (1993) Droplet absorption in thick porous material Washburn Denesuk et al., J. Coll.Int. Sc.., 158, 114, 1993 Marmur (1988) Washburn Marmur., J. Coll.Int. Sc.., 122, 209, 1988 Pinned contact line Absorbed dewetting, constant q Starov et al. (2002) Borhan et al. (1993) Droplet absorption in thin porous material Borhan et al., J. Coll.Int. Sc.., 158, 403, 1993 Starov et al., J. Coll.Int. Sc.., 252, 397, 2002 Considered competition between spreading and dewetting while absorbed First fast spreading without absorption, then dewetting absorption with constant q: maximum radius Dry Spreading + Aspired Dewetting 8mx (dx/dt)/R= 2gcosq Fv (Poiseuille) = FC x a t 1/2 Absorption/Spreading of droplets on thin porous materials Hexadecane in PVA nanoweb Ro = 490 mm dL/dt =kPc/[m ln(L/R)L] Dynamics kPc =1.6 10-4 dyn = ger/(2ko)