Sciencemadness Discussion Board - Synth help for a "Plastic"

Synth help for a "Plastic"

YT2095 - 28-3-2008 at 01:51

do anyone remember or know of a synth for making a "Plastic" that uses fliter paper, ammonia, copper sulphate and I think it used sulphuric acid too?

that`s about all I remember about it, I know it was some early type of plastic and it`s pretty straightforward to make, but for the life of me I cannot remember how it was done

Google isn`t much help, but then I`m no Google-Meister either.

I`m pretty sure it was some sort of Cellulose plastic that used the plain fliter paper fibers as the majority structural element in this "polymer", and it was all Wet Chemistry too.

any help would be great

not_important - 28-3-2008 at 02:32

Rayon via the cuprammonium method, used before the viscose method took over around WW-I. Dissolve high grade cellulose in tetraamminecopper dihydroxide solution, force that through narrow openings into an acid bath which destroyes the cuprammonium complex and precipitates the cellulose in the form of a thread.

YT2095 - 28-3-2008 at 03:00

Rayon, Perfect! Thank you Very much for that

Now my searches will be a little more fruitful.

chemkid - 28-3-2008 at 05:02

I read that that required strong ammonia. Does anyone know if it can be done using a weak ammonia solution and just more of it?

Chemkid

YT2095 - 28-3-2008 at 05:11

my thinking would be that if the copper hydroxide reacts with your soln of X% then all`s good, I read that once made it can be crystalised also, so that`s a nice Plus.

"Schweizer's reagent is the common name for the complex tetra-aminecopper dihydroxide, [Cu(NH3)4][OH]2. It is prepared by precipitating copper(II) hydroxide from an aqueous solution of copper sulfate using sodium hydroxide, then dissolving the precipitate in a solution of ammonium hydroxide. It forms a deep azure solution. If the solution is evaporated, it leaves blue, needle-like crystals."

taken from: http://en.wikipedia.org/wiki/Schweizer%27s_reagent

I think this will be a nice experiment to do with my Daughter, lots of color changes and "strange" materials made, and nothing Exceptionally Toxic involved.

[Edited on 28-3-2008 by YT2095]

YT2095 - 28-3-2008 at 07:42

I found this too, after my atempt at making Copper Hydroxide Totally failed!

"Copper(II) hydroxide reacts with a solution of ammonia to form a deep blue solution consisting of the [Cu(NH3)4]2+ complex ion, but the hydroxide is reformed when the solution is diluted with water. Copper(II) hydroxide in ammonia solution, known as Schweizer's reagent, possesses the interesting ability to dissolve cellulose. This property led to it being used in the production of rayon, a cellulosic fiber."

taken from: http://en.wikipedia.org/wiki/Copper(II)_hydroxide

I think the problem I had as I ended up with a dark green/black Gel was using to strong a soln of both the CuSO4 and NaOH.

"Copper(II) hydroxide can be produced by adding a small amount of sodium hydroxide to a dilute solution of copper(II) sulfate (CuSO4 · 5H2O). The precipitate produced in this manner"

underline "Small Amount" and "Dilute".

taken from same site.

not_important - 28-3-2008 at 08:14

Quote:

Originally posted by chemkid
I read that that required strong ammonia. Does anyone know if it can be done using a weak ammonia solution and just more of it?

If the ammonia is too dilute then some of the cupric hydroxide will not dissolve, if too dilute then almost none of it will. Diluting concentrated solution of the complex results in the precipitation of cupric hydroxide.

Similarly diluting a solution of cellulose in the complex will give at first a precipitate of cellulose, then of cupric hydroxide.

YT2095 - 29-3-2008 at 03:51

this seems to be a simple enough synth:

"PROCEDURE:

1. Dissolve 25.0 g of CuSO4.5H2O in 100 mL distilled water. Heat the water to accelerate the dissolving process.
2. Dissolve 8.0 g of NaOH in 200 mL of distilled water.
3. Mix the cooled NaOH solution with the copper sulfate solution. Collect the resultant gelatinous precipitate of Cu(OH)2 by filtration. Wash the precipitate with three 10-mL portions of distilled water. If using 11.0 cm filter paper, several filtrations will be required because of the large amount of precipitate produced.
4. Measure 70-mL concentrated NH3 (aq) into a 250-mL Erlenmeyer flask. Shred four pieces of 11.0-cm filter paper. Add the Cu(OH)2 precipitate carefully along with the filter paper to this flask and stir. This should result in a deep purplish-blue solution of tetraaminecopper (II) hydroxide, referred to as Schweizer's reagent. Stopper the flask and stir periodically for 24 hours. Use a magnetic stirrer, if available.
5. Take up the contents of the 250-mL Erlenmeyer flask in 10-mL increments in a 10-mL or 50-mL syringe. Squeeze out the contents into a 1000-mL beaker contained 300 mL of 1.6 M sulfuric acid. Be sure that the tip of the syringe or pipet is under the surface of the acid. A crude 'thread' should form.
6. The clumps of threads can be washed free of the solution to show the white color of rayon. "

taken from: http://www1.umn.edu/ships/modules/scimath/polymer2.htm

I have my reagent made now, and I`m letting it sit for the 24 hours with plain filter paper and a little pure cotton wool (I want to see which is affected the fastest).

I will be trying the Above method, later on, although I would like to know what Exactly is "Concentrated NH3 (aq)" in a Percent?
although it Would seem that the ammonia soln I have here is sufficient to make the correct clear Blue color.

not_important - 29-3-2008 at 05:04

Concentrated ammonia solution generally means a concentration of 13 M / 25% or above; this is a density of 0.90 or less.

YT2095 - 29-3-2008 at 05:41

Hmmm... I don`t think mine is anywhere near that, it`s about 10% to my estimate, in that case I expect my Rayon reaction will take much longer.

I DO have the lovely blue solution, and can indeed verify your comment: "If the ammonia is too dilute then some of the cupric hydroxide will not dissolve".
not all of mine did dissolve in proportion to the amount of ammonia I had to use.

however, I expect there will be Some result given enough time, ideal or otherwise.

oddly, I tried to evaporate a little of this soln, I didn`t get a Blue needle like crystal, rather the few drops I put in the petri dish formed a "skin" on the top with a strange effect like petrol on water rainbow with a slight metalic sheen.
now that it`s Dry, one side has the deep blue solid and the other is closer to the Hydroxide color (turquoise).

YT2095 - 31-3-2008 at 01:24

well something`s gone wrong, it`s been 2 days now and there is No sign at all of the cellulose dissolving in any way.

I set up an alternative experiment to make the tetraaminecopper (II) hydroxide but simply putting copper metal directly into the ammonia soln, it`s gone a very deep blue now and is equally in color density as the one trying to dissolve the cellulose.

I have a feeling that my ammonia soln simply isn`t strong enough, and having the right Color may not necessarily mean I have a working reagent.

Time to get the Ammonium Nitrate and NaOH out I think.

not_important - 31-3-2008 at 06:35

Or you could "distill" ammonia from some of the 10% solution into another portion of the 10%. This was how I procured saturated ammonia when I was quite young, using simple flasks, cork stopper, and aquarium air hose to turn a liter of household ammonia into 150 ml of very strong ammonia and a lot of very weak ammonia that I used to make a little NH4Cl.

When you evaporate it, if there's to little ammonia the complex will lose ammonia along with the evaporating water. When there is much excess ammonia the complex will hold together. Also by using concentrate ammonia you can use less liquid overall, meaning there is less water to evaporate.