Adsorption of polymers from solution by solid surfaces
• Mixing and diffusion in wet end system
• These motions lead to particle-particle or particle-polymer collisions.
• Collisions lead to attractive forces between negative and positive charged species
• Other forces – Hydrogen bonding – Van der Waals forces
Adsorption of polymers from solution by solid surfaces
• Polymer adsorption isotherms
– Rapid adsorption occur
– On the order of a few seconds or less for the major portion of the reaction
– Equilibrium retention level
Adsorption of polymers from solution by solid surfaces
• The effect of fines level on cationic starch adsorption by pulp
– Fine: high specific surface area
– Table 5.8 Effect of fiber and fines surface area on polymer adsorption
Surface science and papermaking
• Source of surface tension
• Papermaking phenomena and surface tension
• Interaction between liquids and solid surfaces
– Young equation
Association colloids 1
• Colloidal system: have a large number of small solute molecules associate together to form an aggregate which is very much larger than the individual solvent molecules and fall into the colloidal size range associate by van der Waals force: associate colloids
• Application of associate colloids in the paper industry: Table 5-11
Association colloids 2
• Surface activity
– Amphipathic association molecules: cause a dramatic, spontaneous lowering f the surface or interfacial tension with very low concentration
• Micelle formation
– Critical micelle concentration (CMC)
• Detergency
• Emulsions
• foams
Summary of this chapter
• Brief review of colloid and surface science concepts
• Adsorption of cationic polymer: critical step in the function of many additives
Wet end chemistry ch 6
WPS, CBNU
Need for charge measurement
• The charge on the colloidal particles plays major roles in the stability of their dispersions, which affects following properties. – Fine retention
– Filler retention
– Size retention
– Pigment slurry preparation
– Size emulsification
Surface charge on papermaking fiber and fines
Summary
• Charge measurment in wet-end chemistry
– Charge in solid surface
– Charge in spherical small particle
• Charge measurement device
– Progress in device with different method
– Same physical nature in solid surface or spherical particle
