[Checkpoint #2 - 4/14/17]
Results and Discussion

For the second test, we wanted to test out better mold designs, find ways of inhibiting clumping (squeeze bottles should mean a bigger nozzle hole) and testing different syrup viscosity.
 

TEST RESULTS & OBSERVATIONS:
 

Syrups Used:

• Thinner syrup: same syrup used in test 1 (Checkpoint 1)

• Thicker syrup: syrup from test 1 boiled for 1 minute

  • Waited for syrup to boil, timed it 1 minute after it
    started to boil
     

Carbon Used:

• % carbon used was visually estimated. The exact %
  carbon is not crucial in the current tests while we
  determine the proper injection methods.The % carbon
  used was significantly less than what will be used in the
  final sample using epoxy

• 10 mm fibers produced the best results in these samples. We decided to use mostly 10 mm fibers because the other fiber sample was difficult to squeeze out of the bottle. The squeeze bottle was not
  appropriate for the other mixture.

• The 5 mm and 20 mm mixtures got mixed up in one of the tests by accident. The results do not provide much data on these due to air leakages. Too many variables were involved.
   

Vacuum Pump: 1/6th atm pressure, was weak so the flow was really slow
 

3 Channels:

• All were leaking air, so we could not vacuum pump

• Thicker Syrup with 10mm fibers: Syrup exited the
  channels before the carbon, so the carbon became
  more concentrated as more of the mixture came out
  of the channel

• Air pockets between the channel exits, though fairly
  small
   

2 Channels:

• Thicker Syrup with 10 mm fibers: Similar to 3 channel
  case

• Thinner Syrup with 10 mm fibers: Carbon clogged in
  the fork and the channels with a more extreme
  gradient then the thicker syrup case

• Air pocket between the two channel entries, much
  larger than the ones in 3 channels
   

1 Thin Channel:

• Thicker Syrup with 10mm fibers: Carbon concentrated
  in the funnel, similar gradient as before

• Thinner Syrup with 10mm fibers: Carbon clogged
  much more than the thicker syrup. Clear chunks in the thin strip
   

1 Wide, Thin Channel:

• Wider channel with 10mm fibers: the concentration was uniform throughout, the fibers oriented perpendicular to the flow. This may be due to the sudden change in width as the channel ends.

• Thinner channel with 5mm and 20mm fibers (we mixed them up by accident: was leaking air, so the pump did not work very well. The results were not as clean as the wider channel, but the fibers were still roughly perpendicular to the flow
   

Squeeze Bottles:

• Difficult to use, could not squeeze things easily. Difficult to close the air gaps, and squeeze the bottle after the initial squeezes.

• Need to look for syringes with right tip type/opening hole
   

Difficulties:

• Determining exact % carbon in the mixture

• Attempted to use a 100 g scale with .01 g precision. The carbon was too light for the scale to read at the volumes we were testing. For the final test, we will need to get a more precise scale for accurate measurements

• Discovered that when we glued with 5-minute epoxy, we put too much, so some of the channels got filled and  

OBSERVATION: 

• We discovered that the a bottle didn't work as well as a syringe because not enough pressure could be applied

• Centrifuging helped with the air bubbles but there are still other problems

• Spreading the mix into channels and then having it meet showed that the fibers aligned in the direction of fiber flow, around sharp edges, there was a pattern of the fibers curved around the edges.

• For a horizontal barriers, the fibers aligned randomly but more were observed to be horizontal. This could be that the fluid is pushed into a smaller channel and has a higher velocity but as it rich a larger channel, the flow slows which forces the back of the fiber to be pushed forward, which might cause the fibers to align horizontally past the barrier.

• When gluing the molds together, do not apply too much epoxy or use epoxy in general. It seems like superglue would be much easier and better.

​

RESULT: 
We discovered that the 10 mm length carbon fiber was best suited for most bottle tip openings, to pay more attention to manufacturing detail (although all of this was done in less than a week for checkpoint #2) and with the configurations that we were able to test, the thicker syrup seemed to work better in some cases. The less viscous the fluid, the more a difference there is between the speed of the fluid and the fibers. The fluid moves faster than the fibers (less adhered) and hence, there isn't a good mix.