Exilva is a three-dimensional network of microfibrillated cellulose suspended in water. To disperse Exilva completely into the formulation, a certain amount of shear is needed, depending on the product form of Exilva. The shear will open the physical entanglements of the microfibrillated cellulose which are present at rest leading to an open network and maximum surface area.
Remember that you are not dependent on state-of-the-art mixing equipment to disperse Exilva, but the dispersion of the microfibrils are an effect of time and shear force. If you use equipment providing less shear force, you will need to disperse the microfibrils for a longer period:
|Equipment||Stirring speed (rpm)||Time (mm)|
|Dispermat dissolver||2 000||10|
|Propeller mixer||2 000||15|
|IKA-stirrer (3 blade mixer)||750||20|
What I need to consider when adding Exilva microfibrillated cellulose
Depending on the product grade you are using, you need to take the following into consideration;
I am using the Exilva V products:
When using the Exilva V products, it is critical to pay careful attention to the dispersion of the Exilva into your product formulation. When improperly dispersed, you do not gain access to the surface area of Exilva and subsequently decrease the efficiency of Exilva in your final product.
The table below describes the recommended blade speed combinations for dispersing Exilva 01-V. However, as shear is a function of blade tip speed and product rheology, lower tip speed may be enough at higher viscosities. After dispersion is complete, remaining components can be added under letdown/low shear mixing. Exilva 01-V can also be added at later stages of the formulation, if the high shear step is introduced after the addition.
I am using the Exilva L products
The Exilva L products are generally easier to disperse, and do not need the same shear forces as the Exilva V products.
Ensure that you have enough water available in your formulation to allow for incorporation of Exilva L products.
Our recommendations for laboratory testing with Exilva microfibrillated cellulose
- Whenever possible, start with the Exilva L products (2%) to more easily facilitate positive laboratory test results
- Check for a homogeneous dispersion that does not contain any lumps or visible aggregates
- Immediate sedimentation or phase separation might also indicate insufficient dispersion
- If you suspect there is a problem with the dispersion, it might be a good idea to test different dispersion times and methods and see if this makes a difference.