|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Jet breakup in polymer melts
Alexandros A. Fragkopoulos, Alberto Fernandez-Nieves
|
We are collaborating with P&G to produce droplets inside solid PEG. To perform this we are using glass based microfluidic devices. Specifically, we are using a co-flow device where the inner fluid immerges from a glass tip, and the outer liquid drags it along the same difrection (see Fig. 1(a)) [1]. For high enough flow rates of the outer liquid, the inner fluid strestches forming a jet, which consequentially breaks into droplets (see Fig. (b)).
To have a bigger versatiliy on the size of the resultant droplets, we want to induce pertrbation of specific wavelength. We are inducing pressure perturbations of the inner liquid using a mechanical wave vibrator, by peridically pressing the tubing carrying the inner fluid between the vibrator and a fixed object [2]. We control the frequency of the vibrator using a function generator. A schematic of such a setup is shwon in figure 2.
Finally, we want to use polymer melts as the outer liquid to encapsulate the resultant droplets. For that reason, we need to perform the experiment at high enough temperature. For that reason, we are using a syringe heater to melt the PEG 8000. In addition, we wrap the tubing carrying the PEG in wire, and we pass electricity through to keep it warm. Finally, the microfluid device is kept warn using a heavy duty heat gun, while the device is enclosed in a cardbox (See setup in Fig. 3).
We can see some of the resultant experiments in the below videos. The outer liquid looks spotty since it is a polymer melt. In addition, we see a change to the perturbation wavelength and droplet size, just by changing the frequency of the applied perturbation.
Video. 3: Jet breakup
|
Soft Condensed Matter Laboratory, School of Physics, Georgia Institute of Technology
770 State Street NW, Atlanta, GA, 30332-0430, USA
Phone: 404-385-3667 Fax: 404-894-9958
alberto.fernandez [at] physics.gatech.edu
