Damage to the fibres may occur depending on the ultrasonic intensity and time of dispersion. So, by controlling these two parameters we can do the dispersion without any damage.

It depends on the mechanical properties of your fibres. When I was sonicating exfoliated graphite 20 years ago, the particles were totally destroyed, but the indiividual graphite flakes they were made of were nicely separated and intact. At that time, we were controlling the US power, and we were taking care not to heat the suspension too much. In your case, the bundles of fibres will be separated for sure, but it is difficult to predict whether the fibres will be damaged or not. I am afraid that successive trials and errors will let you know. About the impact on the final product, again, this is difficult to foresee, but it might be the topic of an interesting research paper, provided that the damages (if any) are clearly identified, and if a correlation between these damages and a decrease of performances can be identified beyond a given damage threshold.

Alain

Ductility of the fibres will influence the stability. With increasing ductility the danger of fibre damaging will be decreased.

Damage of cavitation on particles (and similarly on droplets in emulsion) occurs presumably from shock-waves and is thought to occur if the particle is roughly of the same size as, or larger than the bubble ambient size (typically a few um).

For fibers, which have a large aspect ratio the conclusion is less clear. Recently, we performed perturbation of single bubble experiments by micron-sized carbon fibers. In a few words the bubble ends up near the fiber and disappears by surface instabilities. Marginally, we noticed after some tenth of experiments that the fiber was slightly damaged. Unfortunately we lost the fiber and coud not examine it with electron microscope, but we will do that someday. Anyway your fibers are much  thinner than ours.

You could have a look at the page of my collegue Sonia Molina-Boisseau in Grenoble who performed insonification of cellulose fibers and observed interesting results and pictures of damaged fibers.

I would say that this interesting issue is still widely open...

Regards.

Yes, the magnitude and specification of Ultrasonication including power and used frequency have significant impact on the final properties of fillers, and in your desirable field of study, I think it can highly affect your product if you consider the unltrasonication at higher powers or frequencies.

In this regard, try to find the optimum power, frequency and time for the sonication based on experimental evaluations.

I think Damage to the Polymer may occur depending on the ultrasonic high powr of dispersion. in that the viscosity will also affect the cavitation of the liquid