Poor Filler Dispersion: Symptoms and Corrections
How to distinguish incomplete dispersion from an incorrect filler level, and what actually improves dispersion in a production mixer.
"Bad dispersion" is often diagnosed when the real problem is the wrong filler level or an unfinished chemical reaction. Separating the two saves a lot of wasted mixing energy.
Symptoms of genuinely poor dispersion
- •Visible agglomerates on a torn or cut surface.
- •Tensile strength, tear strength and abrasion resistance all below expectation together.
- •High viscosity that does not fall with further mixing.
- •Large scatter between test specimens from the same batch.
Check these before adding mixing energy
- •Was the filler added with the oil, in portions? Adding oil separately from filler usually causes soft, low-shear mixing and poor incorporation.
- •Is the dump temperature high enough? Dispersion needs sufficient temperature and shear.
- •Is the polymer masticated enough at the start? A very high viscosity polymer cannot develop the shear needed.
- •For silica, was the silanisation window met? Incomplete coupling looks like bad dispersion but is a reaction problem.
What actually helps
Increase the number of mixing stages rather than the speed of one stage, keep the ram pressure and fill factor correct, and check rotor clearance — worn rotors are a common and frequently overlooked cause of a slow decline in dispersion quality.
Ask for micrographs or a dispersion rating from your supplier if you suspect a chronic problem. ## Need the documents or today's price? Send us the grade, quantity and destination port — we return a quotation with COA and MSDS attached. Email manager@fipolymer.com or use the inquiry form on this site.