Tube Manufacture
1 mold is assembled.
You should have 2 spare o-rings, spare (long) PTFE tubing, tygon tubing (which needs to be cut and dispensed with each mold)
1. Cut Tygon tubing into two small pieces
2. Insert one piece of tygon tubing into the end of the PTFE tube.
3. If not in place already (I think they are), put o-ring into the groove cut on the FEP-coated stainless steel tube.
4. Insert the s/steel tube (o-ring close to you) into the PTFE tube and place tube through the hole in the tygon tubing (which should be at the far end)(Fig).
5. Push the s/steel rod into the PTFE tube fully. A large length of this rod is now sitting on the other side, supported by the tygon tubing (Fig) .
6. Place the other tygon tubing piece into other end, and then push the FEP rod through this. Have the o-ring sitting close to the tubing, with the FEP-coating exposed on the outside at both ends (Fig).
7. Using two 30-gauge needles, push one through the tygon tubing near the o-ring to permit air to escape, and attach the other needle to your monomer mixture (Fig).
8. Holding the mold upright, inject the monomer so that all air is removed.
9. Remove the top needle, then the lower one, still injecting so that air doesn’t come in to replace the volume of the needle tip as it is removed.
10. The cast tube will be of similar dimensions to the tygon tubing.
To remove:
1. Use tweezers to pull off the tygon tubing from both ends.
2. Pull from the non o-ring end to remove the cast tube.
3. Either leave on or pull off the FEP-coated s/steel tube.
Purposes:
O-ring: To assist in removal of the cast tube from the mold. Pull from the non o-ring end to remove the cast tube.
Tygon tubing: To maintain symmetry of the central rod, and the resulting cast material. Also allows injection through it.
PTFE tube: ID forms the OD of the cast tube. Should release the cast tube easily.
FEP-coated s/steel tube. FEP-coating permits the easy release of the cast tube – s/steel provides rigidity and straightness for symmetrical casting of a tube. Don’t damage the FEP-surface.
35wt% H2O
65wt% HEMA
0.25% EDMA
0.5% APS
0.5% TEMED
Note: This will polymerize FAST. Only do one mold per monomer mix. Suggest splitting your monomer mixture into the number of molds you will have (ie. 4 molds, split into four) after you add the APS. In this instance, the TEMED is added last, and you have 3-4 minutes to get it into the mold. Do this one mold per monomer mix.
1. Prepare the mold ready for injection.
2. Add the TEMED last – start a stopwatch now!!
3. Cast for 20 minutes (from when the TEMED was added). You may wish to vary this time to get different effects.
4. Remove from mold, and add (with FEP-coated s/steel tube still attached) to H2O, or a 98:2 ratio of H2O: HEMA. Once again this ratio can be varied. Different effects will be seen.
5. After one hour place in water, or exchange water present.
6. After 5 hours remove the tube and take off the FEP-coated s/steel tube.
7. Soxhlet/treat as any device.
Clean components after each use (soak in water) Do not roughen the FEP-coating. Use new PTFE tubing if release becomes difficult.
Monomer Composition:
There has been no morphological investigation into the nature of the porous coating of such cast tubes, only that a white material forms over the tube, and is bound to it.
Monomer composition: