Ways of joining two different polymers

  • #1

Main Question or Discussion Point

Hello everyone!
I am currently working in the field of polymer composite materials.I was wondering what are all the possible ways to join two different polymers together? For example, Ultra-high-molecular-weight polyethylene (UHMWPE) and Polycaprolactone. I know that welding is process that joins materials together, but I would like to know more about the other ways. I would be very grateful if you could provide me with any information.
Best regards
 

Answers and Replies

  • #2
jrmichler
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Two companies that specialize on bonding almost anything to almost anything are Loctite, www.loctite.com, and Master Bond, www.masterbond.com. They can even bond UHMW.
 
  • #3
  • #4
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There is also the possibility to use something called "solvent bonding", which does not rely on an adhesive (third material layer between the two polymers).

For this approach, it is required to know a chemical that is a solvent for both polymers. When applying the solvent to one surface, and then putting the other polymer on top, will lead to the partial dissolution of the surface-layers of the polymers. The polymer chains of the different polymers will entangle each other. When the solvent has evaporated the two polymers will be joined better than using any adhesive.

However, this approach is a more research heavy approach, as it does not rely on ready-made adhesives. So using it is mostly for special purpose applications.

/Rune
 
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  • #5
Tom.G
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it is required to know a chemical that is a solvent for both polymers.
Or perhaps a mixture of an appropriate solvent for each material? Both the solvents and the base materials would probably have to be misciple though.
 
  • #6
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Or perhaps a mixture of an appropriate solvent for each material? Both the solvents and the base materials would probably have to be misciple though.
The funny thing is actually that a mixture of solvents will behave as a single solvent which either dissolves either or both of the polymers, or not.

This can all be investigated using Hansen Solubility Parameters, which turns the problem into a geometric problem. The polymers will be represented by ellipsoids in a 3D "solubility" space, and solvents are represented by points. If the polymer ellipsoids have an overlap it is theoretically possible to find a solvent, or solvent mixture, which dissolves both polymers :-)

https://www.hansen-solubility.com/HSP-science/sphere.php
 
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  • #7
Baluncore
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There are also mechanical ways where the different items are made to key together.
One example is the angular dovetail joint, or rounded like the lobes used in jigsaw puzzles. A zipper is also a solution.
Another is a helical thread such as a screw.
 
  • #8
CWatters
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The car industry has done a lot of work on adhesives. Not my field really. I've only just recently discovered how good some polyurethane adhesives are at sticking metal and plastic. Think the car industry has used them for decades. There are also super glue variants that retain flexibility when set, useful if you have vibration or flexing substrates.

If you do work with laminating composites and resins or concrete floor screeds, you sometimes run into issues with surface effects such as waxy layers forming. Special treatments are used/needed before you can use adhesives to join such materials (chemical etching, gas plasma treatment etc).

I'm sure whole books must be written on the subject.
 
  • #9
Tom.G
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Another company that does a lot of adhesive work is 3M.

Also, the automotive parts stores sell Weather Strip Adhesive that is *very* tenacious.
 
  • #10
Thank you very much! I really appreciate your help! I'll try to find an appropriate solvent!
What about 3D printing? Do you think it could be possible to join two polymers -UHMWPE(the base) and Polyurethane/Polycaprolactone/Polylactide that way?
 
  • #11
CWatters
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What do you mean by "join"? Would a mechanical joint be acceptable? For example bolts and nuts? I can imagine it might be possible to 3D print rivets or similar.
 
  • #12
I have to investigate the structure and mechanical properties of transition layer between two different massive polymers.
 
  • #13
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Your base polymer has melting range far below other mentioned. This makes possible to use very spacific variant of welding: attach your PE material to the other, heated to temperature higher than Mp of PE, but lower than the second material. PE probe should be also hot, but below its MP. Both materials should be fresh removed from thermostats or furmaces. Surfaces to be contacted should be strictly parallel, so some machinery would be halpful. Just keep them in contact (light pressing should be helpful) and wait for cooling.
Many years ago I had similar joining problem, solved by technicians from my Institute's workshop. They used self-made installation providing a narrow (about 2 mm in diameter) and wide (many centimeters) microwave field. Both polymeric parts were slowly inserted into the field and keep contacted for some minutes. I heard about similar instruments using ultrasonic field instead of microwave one.
Best regards,
zbikraw
 

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