Agglomeration mechanism of nanoparticles
The agglomeration of nanopowders refers to the phenomenon that the primary nano particles are connected to each other during the process of preparation, separation, processing and storage, and large particle clusters are formed by multiple particles.
Agglomeration is divided into soft and hard types.
Soft agglomeration: refers to clusters or small particles formed by connecting primary particles at points or angles, which are adsorbed on large particles. It is generally believed to be caused by static electricity and Coulomb force between atoms and molecules on the powder surface.
Why soft agglomeration happens?
Size effect, surface electronic effect, surface energy effect, close range effect
Hard agglomeration: refers to the primary particles are connected by faces and cannot be separated without external energy. The surface area is much smaller than the sum of the surface area of one single particle, and it is very difficult to disperse again.
Why hard agglomeration happens?
Chemical bond theory, sintering theory, crystal bridge theory, surface atom diffusion bond theory
Since reunions of nano materials are inevitable due to their owe properties, how can they be dispersed?
Dispersion of nano powders: the so-called nanopowder dispersion refers to the process of separating and dispersing particles in the liquid medium and uniformly distributed throughout the liquid phase, which mainly includes wetting, de-agglomeration and stabilization of dispersed particles stage.
Nano powder dispersion technology is divided into physical and chemical methods generally.
Physical dispersion:
1. Mechanical agitation and dispersion includes grinding, ordinary ball mill, vibratory ball mill, colloid mill, air mill, mechanical high-speed stirring
2. Ultrasonic dispersion
3. High-energy treatment
Chemical dispersion:
1. Surface chemical modification: coupling agent method, esterification reaction, surface graft modification method
2. Dispersant dispersion: mainly through dispersant adsorption to change the surface charge distribution of particles, resulting in electrostatic stabilization and steric barrier stabilization to achieve the dispersion effect.
Well dispersion is a key step to achieve best properties of nano materials. It’s a bridge between nano materials and pratical application.
Hongwu Nano also offers the customization service to make nano powders dispersion.
Why Hongwu Nano can serve in this field?
1. Based on rich experience in the field of nanomaterials
2. Rely on Advanced nano technology
3. Focus on market-oriented development
4. Aim to offer better service for our customers
Post time: Mar-11-2021