Dispersion of organoclays in epoxy is a complex process, which takes place during the pre-mixing step and the curing step after mixing with hardener.

Both pristine and commercially treated clays tend to form stacks rather than individual platelets owing to their layer structure and the strong ionic and hydrogen bonding forces resulting from the cations and (in some cases) water molecules located between the layers. In most cases, the stacks combine and form large aggregates as a result of such strong secondary interactions. Consequently, it is very difficult to overcome these interactions to disperse the clay layers individually in the epoxy matrix, especially when the two phases are incompatible.

During the fabrication of an epoxy nanocomposite, normally, the clay is first premixed with the liquid epoxy resin. In the absence of the curing agent, the system can have an extended shelf life at certain elevated temperatures. Therefore, different means such as mechanical shear and elevated temperature can be used to facilitate the dispersion. In the end, the system is cured by the use of hardener. At this curing stage, external shear stress may not be applied, but further dispersion, more specifically, intercalation and exfoliation, can continue to take place at the beginning of the curing as the hardener and/or intermediate molecules are still mobile enough to diffuse into the clay galleries; the driving force behind this diffusion is chemical thermodynamics.

Compatibility between epoxy, clay including intercalant, hardener etc. Sometime does not need to have strong mechanical shear, ultrasonication to obtain the good exfoliation of clay in epoxy.

When the clay aggregates are immersed in a solution such as that of an epoxy resin, the resin molecules tend to diffuse into the space between the clay stacks.

If there is significant break-up of the aggregate due to motions such as shearing, or collision against hard obstacles. The diffusion will take place.

Etc.

You can have a look at attached articles for your interest.

 Regards,

TD

you did not give too many details, by you can do it by

1. grafting of something on the surface

2. extrusion

3. surface polymerization

Hi dear Sumit,

You can try to use modified clays with some kind of quaternary alkylammonium salts which in some cases are more compatible with the resin, because the space between each layer is more spaced and they can become more exfoliated. you can look at this paper: http://onlinelibrary.wiley.com/doi/10.1002/pc.23101/abstract for more information about clay based nanocomposites. And this other paper as information about the modification process: http://onlinelibrary.wiley.com/doi/10.1002/pc.20667/pdf

Regards

Additionally, you can do several round of centrifugation to remove clay aggregates, i.e:

In my case I need about 3 rounds to get rid of all aggregates, starting with 1 wt% clay in water and ending up with about 0.35 wt% clay in water.

Dear @Florian @Daniel @Lilian,

thanxx for your valuable suggestion. This will help me for the further work proceeding.

Dispersion of organoclays in epoxy is a complex process, which takes place during the pre-mixing step and the curing step after mixing with hardener.

Both pristine and commercially treated clays tend to form stacks rather than individual platelets owing to their layer structure and the strong ionic and hydrogen bonding forces resulting from the cations and (in some cases) water molecules located between the layers. In most cases, the stacks combine and form large aggregates as a result of such strong secondary interactions. Consequently, it is very difficult to overcome these interactions to disperse the clay layers individually in the epoxy matrix, especially when the two phases are incompatible.

During the fabrication of an epoxy nanocomposite, normally, the clay is first premixed with the liquid epoxy resin. In the absence of the curing agent, the system can have an extended shelf life at certain elevated temperatures. Therefore, different means such as mechanical shear and elevated temperature can be used to facilitate the dispersion. In the end, the system is cured by the use of hardener. At this curing stage, external shear stress may not be applied, but further dispersion, more specifically, intercalation and exfoliation, can continue to take place at the beginning of the curing as the hardener and/or intermediate molecules are still mobile enough to diffuse into the clay galleries; the driving force behind this diffusion is chemical thermodynamics.

Compatibility between epoxy, clay including intercalant, hardener etc. Sometime does not need to have strong mechanical shear, ultrasonication to obtain the good exfoliation of clay in epoxy.

When the clay aggregates are immersed in a solution such as that of an epoxy resin, the resin molecules tend to diffuse into the space between the clay stacks.

If there is significant break-up of the aggregate due to motions such as shearing, or collision against hard obstacles. The diffusion will take place.

Etc.

You can have a look at attached articles for your interest.

 Regards,

TD