Week 9 Update

Due to high humidity, above 35% every time we were able to get to the lab, we were unable to accomplish any spinning this week.  We mixed a solution of PAH, with a ratio of 1 mil of PAH to 3 mils of water, in order to make a mat to compare the PAH/UD90 to, but as previously noted, were unable to spin it due to the humidity. The weather has not been cooperating.

Week 8 Update

Once again, the high temperature and humidity is making it hard to spin.

History of Electrospinning

Electrospinning has a long history, and has been, though not widely known outside of the materials science community, long been used as a method of producing polymer fibers and mats for a number of uses.

The process of electrospraying (the process of small droplets exiting the liquid rather than a thin stream) was first discovered in the late 16th century by William Gilbert.  He discovered this by placing an electrically charged piece of amber near a drop of water, which would cause droplets to shoot towards the amber when placed at the right distance and charged to the right amount.  This discovery sat for more than four hundred years before it was really used again: in 1902, two people separately patented the process of electrospinning (the more refined process of using electricity to draw out a fiber rather than droplets from the solution).

A decade later, John Zeleny began to study electrospinning from a mathematical perspective, attempting to understand the theoretical basis behind electrospinning and to model it.  This work was not completed until the 1960's, when Sir Geoffrey Taylor successfully modeled the fluid cone formed at the tip of the needle during the process of electrospinning - a cone now called the "Taylor Cone" due to his work in examining it.

Though electrospinning had been known for a long time, it was not really made practical for commercial purposes until the work of Anton Formhals.  In 1934 (and again in 1940), Formhals patented a refined method of spinning which solved a number of technical issues preventing it from gaining widespread use before then - namely the fact that the fibers could not dry fast enough to be collected in a solid form.  Formhals solved this by introducing a moving base for the fibers to land on, giving them enough time to dry in a process similar to a standard spinning drum.  This led, in 1939, to the first widespread use of electrospinning: a factory was established in the Soviet Union to produce BF (Battlefield Filter), a filter designed for use in gas masks.  By the 1960's, millions of square meters of BF were produced every year.

Week 6 Update

We attempted to spin 1 mL of our polyallimine/UD90 solution this week, with mixed results.  The solution spun a little bit, but there was also some spraying.  This could be due to air bubbles getting into the solution.  Temperature and humidity (about 20%) were probably not an issue, since both were close to ideal.  Next week we will continue to attempt to spin the solution.

Week 5 Update

We were unable to spin this week, due in part to the much higher humidity and the higher temperature in comparison to previous spinning sessions.  Both temperature and humidity have an effect on electrospinning - in the case of polyalhimine and milled nanodiamonds, higher humidity has the effect of raising the average fiber diameter up to a point, after which the solution becomes impossible to spin.  Hopefully, next week will be cooler and less humid due to the recent thunderstorm, which will allow our solution to spin again.  Also coming up next week: a post on the history of electrospinning.

Week 4 Update

• We created a solution of polyallimine / UD90 (milled nanodiamonds) and attempted to make it more viscous by evaporating the water with a vacuum pump.  Unfortunately, putting it in the vacuum pump for a long period of time caused the nanodiamonds to clump as well as evaporate the water.
• We created another solution of  polyallimine / UD90 and will attempt to spin it next week, after evaporating the water in short bursts and rotating the solution each time.

Hello World!

This is the blog for Drexel Engineering 103, Group 045-02.  Our names are David Freiberg and Noah Watson.  Our project (at least at this point) is to find a way of electrospinning a composite solution with nanodiamonds distributed throughout to strengthen it.  In future posts, we'll have bios, pictures, text updates, backgrounds on the science behind elctrospinning, and more.