sanjay - 12-8-2004 at 10:41
i want making a vinyle eraser and what type compound i use?
i try this compound=
poly vinyle cloride
dop
calsium carbonet
stabiliger
if any one know tell me
thank you
Esplosivo - 12-8-2004 at 11:41
Not to critisize you or anything, far from that, but could you please explain yourself better (and in better english if possible). I cannot understand
exactly what you're after, is it a compound or a mixture of chemicals?
Geomancer - 12-8-2004 at 16:53
Yes, your post is well nigh incomprehensible. As I interpret, you're trying to make a plastic pencil eraser using a formulation of PVC, Dioctyl
Phthalate, calcium carbonate, and a "stabilizer" (what's that for?). This should work out, although maybe not in line with commercial
offerings. Googling "pencil eraser formulation" gives one interesting (though cryptic) result. Apparently, you might want to try a different
plasticiser, although I can't tell if this was suggested for performance or toxicity reasons (toxicity I think).
IvX - 12-8-2004 at 21:31
You want to make something from PVC? You think your gonna do this by adding PVC,calcium carbonate and some stabilizer? Better luck to just melt/shape
the PVC.
sanjay - 12-8-2004 at 21:46
that is called pvc compound not a mixture.I trying to make a plastic pencil eraser using a formulation of PVC, Dioctyl Phthalate, calcium carbonate,
and a "stabilizer".
Geomancer - 13-8-2004 at 15:10
IvX: He's using a "plastisol" process. The polymer powder is mixed with a plasticizer, and then the stuff is heated. The plasticizer
particles swell/dissolve, and form a gel upon cooling.
On a related note, I'm currently experimenting with starch plastisols using plasticizers other than water. So far I've made a weak gel
with glycerine. Any ideas?
IvX - 14-8-2004 at 00:36
Uhh thanks I get that but I'm still confused by what a 'plastic pncil erasor' is.
Freaky idea but you could try ground rice with a little water or milk.Theyre used for making some (crapy)herbal glues.
Starch Plastisol
Geomancer - 21-8-2004 at 12:00
I did another experiment with starch based gels today. The purpose was to determine the "gelatinization" temperature of corn starch in
glycerol as compared to water. Both liquid samples were mixed with 1/2 the volume of starch, and heated in a sand bath over the stove. Unfortunately,
my heating technique leaves a bit to be desired, resulting in very uneven heating. This makes it very difficult to determine the desired temperature
with any precision. Anyhoo, I figure gelatinization occurs at about 80-90C in water, 150-170C in glycerol. Due to the uneven heating, both gels began
to boil before the mass was fully cooked, and the glycerol gel showed some signs of decomposition (presumably of the starch, since no one started
crying).
The completed water-gel is translucent, moderately stiff but not very strong. The glycerol gel is slightly softer, maybe stronger, sticky and
pretty much transparent. It's hard to describe, certainly stronger than Jello but less strong than most jellied candies.
I would like to be able to use the product as a binder for rocket propellant, but it's still a bit weak. How to get stonger gel without using
more starch? Special high-amylose starches are a possibility, but are not (to my knowledge) available retail. Cross linking might help, but how?
JohnWW - 21-8-2004 at 13:25
Nitroglycerine, also known as glycerol trinitrate (it is a true nitrate ester, not a nitro-compound with C-N bonds), has a melting point of only
13.3ºC. It deteriorates if stored for prolonged periods at high temperatures, due to auto-oxidation and its becoming a runny liquid. This is why it
is sold as dynamite in which it is absorbed into diatomaceous earth or powdered pumice or talc or sawdust, and in liquid-proof containers. You should
store it in a refrigerator.
John W.
Geomancer - 21-8-2004 at 18:37
JohnWW: I'm using plain glycerol, not the nitro-ester. If I can obtain decent physical properties, the gel would be used to bind potassium
nitrate, hopefully giving similar ballistic properties to existing sugar/KNO<sub>3</sub> propellants, with improved handling and lower
elastic modulus. You may be getting confused with double base rocket propellants, made with a nitrocellulose plastisol process, where nitroglycerine
serves as the plasticiser.