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Need a solution to bond PE to itself

We have some polyethylene sheets that we are trying to bond together at the seam (overlapping them), we have tried various ways to make it stick to itself but have had no luck. We were told that it can only stick to itself and nothing else is that true, or is there a glue or some sort of adhesive to bond this material? We have tried using an appropriate heat gun and rods of PE and we find that the sheets curl way before the rod melts, the sheet is 1/16 inch thick and the rod is not much larger that the sheets. Can you please help? 

Thank you,

Albert De Leon
Cold storage warehouse - Lamont , California, United States
2004

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If you search the earlier letters you will see that it has generally been felt that PE cannot be glued, but there are some replies claiming it now can be glued under the right conditions. I am confused about your statement that the sheets curl before the rod melts; these rods are meant to be used in an electric heat gun that preheats/pre-melts the rods before they touch the sheets. But 1/16" is quite thin.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

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First of two simultaneous responses -- 2004

Hi Albert,

Firstly, you are trying to weld l/l6" thick material ... and that, even for an expert, needs some care and know how.

Secondly, when you weld Pe, it is advisable to clean (scour, sand, scratch) the surface to be welded. Why? Because Pe seems to build up a micro thin oxidized surface layer and doing this allows one to get/achieve a better weld. This is not so critical with thicker sheets but, I would have thought, essential with l/l6".

Thirdly, re the sheets buckling, it sounds like you are using excessive heat ... also, those sheets might be stressed, ie. not stress relieved.

I like your idea of overlapping the sheets ... but try again but SCOUR the to-be-welded surface first of all.

Laramy have a good little booklet on How To Weld ... maybe you might think I'm trying to teach you how to suck eggs, but thermoplastic welding is an art.

Fourthly, there is no 'glue' for Pe or PP. There is a process, a sort of ionization process, whereby the surface can be prepared to allow it to be plated or cemented but that is not feasible for you.

Lastly, are you SURE that your weld rod is Pe? Heck, I've seen people weld Pe to PP and swear that the weld rod is PP ... in fact I tried this out myself, a perfect weld (so I thought) and showed this to the shop foreman, Canada's first trained German thermoplastic welder, (Alcore Fabricating in 1962) who quickly educated me by just pulling it apart. .... and CLEAN the weld rod, too, s.v.p.

I hope that this helps.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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Second of two simultaneous responses --

I have welded PE that thin, but it tends to have a warp or unevenness because of the heat distortion. You may need to go to a special rod and special made tip. I assume that you are using a speed tip and not a regular "tube" tip and that you are using inert gas. If not, you will find it extremely difficult to do.

James Watts
- Navarre, Florida
2004