PMMA film casting problem
tiberius
> Hi,
> have you tried to add some drops of di-water after the solvent has
> evaporated? I do this with solvent cast films of PHB and it works really
> good. The hydrophobic surfaces of the film and the glass are separated
> because the capillary pressure gets the water in between.
> HIH
> Marcus
>
> "Lucky" <lucky...@hotmail.com> schrieb im Newsbeitrag
> news:5b5a925a.02080...@posting.google.com...
> > I am trying to cast polymer-organic solution
> > (PMMA-toluene) in a container with flat
> > surface. After the solvent evaporized I need
> > the dried film be peeled off easily.
> > I have tried glass petri dish and metal dish
> > they did not work well. In fact I know any
> > PVC or PTFE dish or tray or cap will be good
> > for me. But I cant find the vendor.
> > So I appreciate if anyone can give me any suggestion
> > or reference.
> >
> > THANKS
You might also consider using a solid billet of PMMA and pressing out
a film between two solid, heated plates coated with PTFE. PMMA is
thermoplastic, and you can control the thickness more precisely than
with solvent evaporation, and also avoid the hassles associated with
solvent(emissions, flammability, etc.). This solution should work for
small area films, the cost and engineering difficulties go up
exponentially the bigger your sizes.
For continuous production, you might seek out a firm that produces
polymer sheets off of hot rollers.-Tiberius
Lucky
the casting film things! In fact I am preparing a type
of composite which should go through the solution-casting-
drying procedure. The casted films are subject to DMA
or mechanical test, so the thickness and thickness regularity
should be decent. And the dried films should be easily
be peeled off from the substrate. I tried the DI-Water,
but the films were still stick on the bottom of glass
petri dish. The concentration of the solution I am working
with is just 2wt% polymer in organic solvent so the
viscosity of the solution is very low. So I guess only PTFE
or PVC dish could work.
By the way I have tried to put some solution on the PVC
sheet and left it in hood, after it dried the film was
in ripply shape. I guess that was because the air flow
in the hood made the solution surface not dried homogeneously.
So I may need to put the sheet in a box or oven before
the solution dried, am I right?
THANKS
Marcus Wollenweber
> I tried the DI-Water,
> but the films were still stick on the bottom of glass
> petri dish.[...] viscosity of the solution is very low. So I guess only
PTFE
> or PVC dish could work.
It's worth a try. Perhaps you could also try something like in the float
glass process and cast the solution on another liquid surface. This at least
should generate very smooth surfaces.
> By the way I have tried to put some solution on the PVC
> sheet and left it in hood, after it dried the film was
> in ripply shape. I guess that was because the air flow
> in the hood made the solution surface not dried homogeneously.
I observed the same ripples. I think it's due to the rapid and turbulent
evaporation in the hood. Now I cover the dishes and leave only a little slit
for the solvent to evaporate. These films are quite smooth and have no
rippled surface structure.
Regards
Marcus
Frank Logullo
> > sheet and left it in hood, after it dried the film was
> > in ripply shape. I guess that was because the air flow
> > in the hood made the solution surface not dried homogeneously.
>
> I observed the same ripples. I think it's due to the rapid and turbulent
> evaporation in the hood. Now I cover the dishes and leave only a little
slit
> for the solvent to evaporate. These films are quite smooth and have no
> rippled surface structure.
> Regards
> Marcus
>
should be quite viscous and will stay in place when spread. Liquid can be
used but not in manner described. There are films cast from solution by
continuous extrusion from a slit like cellophane but here the liquid
extracts the solvent. You can do the same thing in the melt which is most
common.
Frank