[christina]

Hwk Q

A water pipe has burst in your home. Being a poor college student and a good organic laboratory student you decide to fix the pipe yourself keeping in mind that a simple patch will not work. You will have to construct your own piping. your are able to order any chemicals needed. Describe what polymer you would make, why, and how.

 
seriously....not sure which polymer to use or what chemicals I need to do the experiment if I did it to create a pipe.

I was thinking of making polyethylene (after some reasearch)

with I think (I may be missing some components and if so please help me out with what I'm missing)

ethylene +

Ziegler-Natta catalyst (TiCl4)+

alluminum based co-catalyst  Al(C2H5)3

Other than that I'm not sure how I'd put them together to do the polymerization rxn.

I need help on this Please 

Thank you very much

[agrobert]

Thats an idea.  What about PVC.

http://en.wikipedia.org/wiki/Polyvinyl_chloride

How involved is your synthesis supposed to be.

ethylene -(Chlorination)-> vinyl chloride -(*Activation-light or catalyst)-> PVC

[ARGOS++]

Dear ~Christina~;

Would you allow to have a different Idea, because all three, LDPE, HDPE, and PVC have several disadvantages?

I think one requirement should be that you have not to fix it every ~3 - 5 years, so a few properties of the plastic pipe must be kept in mind:

• a.)  The pipe should be rugged enough to hold during summer and a cold winter too, because if a part may be also on the outer side of the house.
• b.) If it should be used for drinking water then it should not contaminate the water in any way.
• c.) If for waist water, it should resist against strong bases and also against acids and oxidiser as Bleach.
• d.) You may think of others too, but that’s already enough to put all three out of the race.

LDPE and HDPE get “very” hard at cold temperature because their Cristallinity, and are therefore very fragile during winter time.
PVC requires a Lot of “Plasticizer”, because PVC is by its nature very brittle, and that’s a real disadvantage for drinking water, but also for waist water, because with oxygen and other chemicals PVC turns with time back to its brittle state.

IMHO I would use/synthesize PP, and maybe mix it later with another Thermoplastic to avoid Cristallinity as much as possible too.
PP doesn’t need “Plasticizer” and has a quite excellent resistance against almost all chemicals.
As a Thermoplastic it is also easier to form and bring into shape.
It has also other good properties as you can see on:   "Polypropylene”.

I hope my small idea may be of help to you.
(In our streets we use recycled PP for waist water.)


Good Luck!
                    ARGOS⁺⁺

[christina]

Thats an idea.  What about PVC.

http://en.wikipedia.org/wiki/Polyvinyl_chloride

How involved is your synthesis supposed to be.

ethylene -(Chlorination)-> vinyl chloride -(*Activation-light or catalyst)-> PVC

I'm sorry but I'm confused as to how this could ACTUALLY be reacted by a "poor college student" that this Hwk Q assumes we are since:

1) isn't vinyl chloride a gas at room temp?
problem with that: it would be in a tube and technically you wouldn't heat it right?
since the boiling point of vinyl chloride is -13.9 C ...


And there are harmful fumes which need to be concerned about...but the most important thing is the temperature....which I don't think you would be able to keep it at to do the rxn in a non lab setting.


plus they want the "how" to actually go about doing the rxn so I would need to list the solvents and type of catalyst I'd use.
Thanks

[DrCMS]

The whole question is stupid, and your teacher is a fool.

Making 1kg or so of PVC, PE or PP require a lot equipment to do it safely, as the monomers are flamable gases and in the case of VC toxic as well.

You might be able to make enought nylon using standard lab equipment but then you have to form your lump of polymer into a pipe which you are not going to be able to do in the lab.

Even just the cost of the raw materials for a small batch of any of these polymers in the lab would be 10's of times the price of buying a length of PVC pipe from a plumbing supply shop.

[Arkcon]

The whole question is stupid, and your teacher is a fool.

Your other statements are true, but this is a common type of question in an organic chem text.  The water pipe bulidup is just to make it "real" for the student, while they go and look up plastic fabrication formulas.

[ARGOS++]

Dear Arkcon;

I fully agree with you!, ─   
Chemistry should have also an Eye  &  Ear for Properties and others, then only juggling with Reactions/Likelihoods and dealing with Moles.

Good Luck!
                    ARGOS⁺⁺

[DrCMS]

The whole question is stupid, and your teacher is a fool.

Your other statements are true, but this is a common type of question in an organic chem text.  The water pipe bulidup is just to make it "real" for the student, while they go and look up plastic fabrication formulas.

Well that just shows how little teachers know about the real world.  It doesn't make it feel "real" to me it is patronising rubbish and should be treated as such.  If the teachers wants a "real" answer why not ask why its easier to buy the pipe from a plumbing shop than try to make a pipe yourself

[Transmutation]

The question assumes that you know how to turn off the water, fit pipes, etc.  It also assumes that you have a suitable mold and suitable lab equipment to do the job.  The question of course does not make sense, but for intellectual satisfaction, why not assume that some strange set of circumstances causes it to make sense?  Say for instance that you have ready access to a large store of chemicals on campus, but due to nuclear war/Hurricane Katrina/killer virus you are unable to just go out and buy new pipe.  Perhaps the campus is under quarantine, and if you want water, you have to make yourself a pipe for it!

Fortunately, you have at least one thing to go on- the broken piece of pipe.  You can probably argue that enough of the pipe would survive that you can keep the two ends of the broken piece, and just cast the new pipe around the old one.  for this, you will need something thermoplastic like nylon.  Nylon can be safely made from liquids without a fume hood.  It is stable in water and low-melting.  If cast sufficiently thick, and if the section of pipe to be replaced is short enough, it should be adequately rigid.  You will need some kind of tools to cast the pipe.  At the very least, you will need a thick dowel rod.  Or a curtain rod.  You also need some way to melt and pour the nylon.  Teflon cookware should be adequate for this, I think.  By placing your dowel rod inside the broken pipe (repaired for use as a casting mold with duct tape), you can form the mold for a crude nylon pipe.  All you have to do is pour molten nylon in with a funnel or some such.  You might want to have another dowel rod to push the newly formed pipe out of the mold.  This method will reduce the diameter of the pipe, which may not bode well for the water pressure situation.

Anyway, that's what I would try.  Nylon is easy and safe to make without safety equipment, can probably be melted in a Teflon skillet for casting, and has good enough properties for the jerry-rigged application.