Anyone have any idea how to fuse rubber?

[Kimsey0]

Hey you guys, just trying to figure this out... great thing to know for making your own dive equip... unfortunely it doesn't work?
Sure thought it would be easy after i heard rubber has a melting point of 250 deg F, man was i ever wrong... i must be overlooking something, here's what keeps happening:
As a test i take two rectangular pieces of EPDM that are about 1/8" thick and clamp them down to where the pieces are right up against eachother, forming an unwelded "seam", i tried heating up the seam @ 250 deg f with a heat gun, and after about 15 minutes... it did nothing, just smoked a bit.... ok so then i took the gun, put it on 1200 deg f, did the same thing, it smoked and turned white.
Then i took a butane torch to it.... it smoked, turned white, then caught on fire... it didn't really matter wheither i held the heat gun/torch close, or far away it would do the same thing just take shorter/longer.... i just don't get it... i see rubber products with, what obviously appears to be welded seams all the time, so.....?
Whats even odder is there is *no* info on the net i could find about this at all...
/shrug
Anyway has anyone here ever successfully welded rubber? What am i overlooking?
(on a side note, the pvc pipes i tried to weld earlier behaved very simularly, but thats a different story)

 

[mike_s]

have you tried Aquaseal?

 

[Kimsey0]

Well, thats glueing... i'm not really talking about that, i'm talking about actual fusion. i really didn't want to have to resort to glue, but i probably will have to, eventually.

 

[cool_hardware52]

Hey you guys, just trying to figure this out... great thing to know for making your own dive equip... unfortunely it doesn't work?
Sure thought it would be easy after i heard rubber has a melting point of 250 deg F, man was i ever wrong... i must be overlooking something, here's what keeps happening:
As a test i take two rectangular pieces of EPDM that are about 1/8" thick and clamp them down to where the pieces are right up against eachother, forming an unwelded "seam", i tried heating up the seam @ 250 deg f with a heat gun, and after about 15 minutes... it did nothing, just smoked a bit.... ok so then i took the gun, put it on 1200 deg f, did the same thing, it smoked and turned white.
Then i took a butane torch to it.... it smoked, turned white, then caught on fire... it didn't really matter wheither i held the heat gun/torch close, or far away it would do the same thing just take shorter/longer.... i just don't get it... i see rubber products with, what obviously appears to be welded seams all the time, so.....?
Whats even odder is there is *no* info on the net i could find about this at all...
/shrug
Anyway has anyone here ever successfully welded rubber? What am i overlooking?
(on a side note, the pvc pipes i tried to weld earlier behaved very simularly, but thats a different story)

Most "rubbers" are thermosets. Google "thermoset"

Tobin

 

[Kimsey0]

Most "rubbers" are thermosets. Google "thermoset"

Tobin

Ohh. Ok that explains everything... i was beginning to wonder if rubber had that "cast iron" principle, as in once it's been cast, if you want to manipulate it again, you pretty much cant - only re cast it. Yeah, that would explain the rubber burning/dissolving whilte trying to remelt it.
Strange thing is i remember reading on the one website i did manage to find while back about roofers using a torch to weld rubber, they must not have meant it like i thought they did, though.
Thanks

 

[Bottomfeeder Brodie]

I have very successfully welded thin plastics with a soldering iron. Not sure wait it would do with rubber if that helps.

 

[spectrum]

I have very successfully welded thin plastics with a soldering iron. Not sure wait it would do with rubber if that helps.

Plastics remain.... plastics.

When going from virgin resin pellets to a molded shape they are only warmed and softened enough to let them it be injected into a mold, the shape of which they assume. The material has not gone through a conversion.

With the soldering iron your are locally remolding the material.

Pete

 

[spectrum]

Have you considered urethanes or maybe vinyl sheeting?

 

[cool_hardware52]

Ohh. Ok that explains everything... i was beginning to wonder if rubber had that "cast iron" principle, as in once it's been cast, if you want to manipulate it again, you pretty much cant - only re cast it. Yeah, that would explain the rubber burning/dissolving whilte trying to remelt it.

I wouldn't use the cast iron as an analogy for a thermoset. Cast iron can be remelted and recast and remelted and recast, much like a thermoplastic can.

Thermosets crosslink once, a better analogy would be Plaster of Paris, i.e. mix it, mold it once and any excess is scrap.

Keep in mind that some elastomerics are thermosets, but today many are thermoplastics.

In general the high temperature elastomerics (think silicone ignition wires for example) are thermosets.

The economics of processsing thermoplastics into finished parts is much better than most thermosets. In the last ~25 years there have been great advances in the properties of thermoplastic elastomers, and these newer materials have replaced thermosets in many applications.

Tobin

 

[captain]

I believe once rubber has been vulcanized the only way to join it is with some type of glue

Vulcanization - Wikipedia, the free encyclopedia