PVC Fabrication 1

[RichGeoffroy]

I heard from someone that you can grind PVC into a powder and combine it with PVC solvent to make a PVC epoxy that can bond PVC together and you can sand it like it's solid counterpart, PVC. I am trying to bond together PVC forms I make from PVC pipe. It would be great if I could make an epoxy to bond these pieces together as if they were manufactured that way. It would make what I do so much easier. Can this be done or is there a better way to go about it. One reason I need to do this, is because when I heat up the PVC to change its shape, I can only bend it in limited ways or flatten it out, if that's what I need to do, but it always tries to go back to its original shape when I heat it so I can only do basic shapes. With an epoxy I can do much more. Let me know what to do, if you have anything to offer, in the form of advice. Thank you.

First of all, the process will not make an epoxy, but it will make a PVC solvent cement. Secondly, why go through all that work when you can purchase it at any hardware store. The joint, however, will not be as strong as the PVC sheet itself. It will very likely break at the bond if you attempt to bend it when it’s too cold; and will come apart if you attempt to shape it when it’s too hot. But it might work at just the right temperature --- but it will take some experimenting to find it.

You can get PVC shapes, other than pipe, from plastics distributors. You can get bar stock, sheet stock, even blocks up to several inches thick for machining.

While PVC solvent cement is the easiest and most common way to join PVC, you can also butt fuse with hot plates, or weld with a hot gas gun and PVC welding rod (this method is not as strong as one might expect; so be careful).

As far as the assembly always trying to go back to its original shape, that’s because your method of fabricating is inducing residual stress --- it’s like stretching a rubber band; it wants to get back to its original shape. You can diminish this effect by annealing the part after fabrication using the following temperature schedule:

1 Hour at 80°C
1 Hour at 70°C
1 Day at 60°C
3 Days at 50°C
7 Days at 40°C
7 Days at 23°C​

Hope this helps.



Rich Geoffroy
Polymer Services Group
POLYSERV@aol.com

 

[daveshoes]

Try "Weld-On #16" thickened solvent cement from the IPS Corporation. This is actually designed for acrylic, but will work with other thermoplastics. IPS makes a whole line of adhesives designed for use with plastics.

Dave

 

[patprimmer]

Dave

Why bother looking for specialist suppliers for a special "Acrylic" solvent cement when (as Rich Geoffroy has already suggested) one designed specifically for PVC is available at any hardware store or plumbers supply house.

It is about as difficult as buying a loaf of bread. I guess that's why the original question was deleted, as this is supposed to be a site for professional engineers regarding their work.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CalculatorDave]

Yes, PVC pipe cement is the most available solvent cement for PVC.

I mentioned the Weld-On solvent cements from IPS because they are available in a variety of viscosities, for filling a variety of gaps.

(Geez, it was only a suggestion).

Dave