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Elmer's Rubber Cement is not the vulcanizing kind!



 
 
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  #21  
Old April 26th 09, 06:13 PM posted to rec.bicycles.misc,rec.bicycles.tech
Tom Keats
external usenet poster
 
Posts: 3,193
Default Elmer's Rubber Cement is not the vulcanizing kind!

In article ,
jim beam writes:

"Vulcanizing fluid has two primary functions. First, it contains
chemical accelerators which vulcanize the repair to the tire. Second,
when dry, it leaves the prepared surface tacky, which helps hold the
repair in place until vulcanization occurs."
http://www.premaproducts.com/Technic...3c9abed.0.html

Cheers,

Carl Fogel



when do we get the review of loctite 404's effectiveness?


When do we get the review of how prune juice and a feed of
sauerkraut plus a couple of fruit smoothies improves an
old-fart sourpuss's outlook, maintains his regularity, and
generally cheers him up, as well as putting a lively glow
in his cheeks?

I love you, too. You remind me of my mom's first in-laws.
They're dead now, and have returned to the flint from which
they were made.


cheers,
Tom

--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca
Ads
  #22  
Old April 26th 09, 06:21 PM posted to rec.bicycles.misc,rec.bicycles.tech
jim beam[_4_]
external usenet poster
 
Posts: 318
Default Elmer's Rubber Cement is not the vulcanizing kind!

Tom Keats wrote:
In article ,
jim beam writes:

"Vulcanizing fluid has two primary functions. First, it contains
chemical accelerators which vulcanize the repair to the tire. Second,
when dry, it leaves the prepared surface tacky, which helps hold the
repair in place until vulcanization occurs."
http://www.premaproducts.com/Technic...3c9abed.0.html

Cheers,

Carl Fogel


when do we get the review of loctite 404's effectiveness?


When do we get the review of how prune juice and a feed of
sauerkraut plus a couple of fruit smoothies improves an
old-fart sourpuss's outlook, maintains his regularity, and
generally cheers him up, as well as putting a lively glow
in his cheeks?

I love you, too. You remind me of my mom's first in-laws.
They're dead now, and have returned to the flint from which
they were made.


cheers,
Tom


i get it. you and chalo. you can't belly up to the facts, so you bleat
some bull**** irrelevance because your freakin' mouth still needs to
work, but you have nothing to actually say.

good luck tom. way to contribute.
  #25  
Old April 27th 09, 12:33 AM posted to rec.bicycles.misc,rec.bicycles.tech
Michael Press
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Posts: 9,202
Default Elmer's Rubber Cement is not the vulcanizing kind!

In article ,
(Tom Keats) wrote:

In article ,
writes:

"When rubber cement is used to bond rubber to itself, the solvent in
the cement swells the substrates somewhat and facilitates the
interdigitation process. After the solvent evaporates, it is hard to
distinguish just where the joint lies.


Okay, but I still nevertheless perceive something going on
that intimates a patch together with the inner tube to
which it is applied.

The bonding force is not a
chemical bond -- no bonds are made or broken; the strength of the bond
is purely a physical phenomenon involving van der Walls and London
forces between two intimately mixed and chemically similar non-polar
hydrocarbon rubber molecules."
http://www.madsci.org/posts/archives...3004.Ch.r.html

I intuit there's something further happening. The
patch doesn't just lie there on the tube like a
flapjack; it's as if the tube is sucking the patch
onto itself. The patch & tube aren't just holding
hands and interdigitating -- they're really cleaving
unto each other and becoming one flesh, like Adam & Eve.

And with that imagery, I think I'll forego this line
of curiosity. It's enough to know how to successfully
patch a tube, without getting into all the messy,
gruesome details. Some things in life are best
left as wonderments. As long as one gets away with
not getting the patch kit instruction sheet inextricably
stuck to their thumb, life is good.


Remove a well adhered patch. You will see no indication
of chemical bond formation.

--
Michael Press
  #26  
Old April 27th 09, 12:37 AM posted to rec.bicycles.misc,rec.bicycles.tech
Nick L Plate
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Posts: 1,114
Default Elmer's Rubber Cement is not the vulcanizing kind!

On 26 Apr, 05:37, " wrote:
On Apr 24, 8:58*pm, (Tom Keats) wrote:



* * * * Tom Sherman writes:


Where can I buy (in bulk) a large amount of the vulcanizing cement
from at the best price?


I was under the impression that vulcanizing requires heat and a curative
to produce cross-linking of the polymers, and "vulcanizing fluid" is a
marketing term.


As I understand it, so-called "vulcanizing" rubber cement
chemically integrates with the existing rubber to which
it is applied. *This effect should be desirable with
regard to tire repairs, since holes in tires are external
and thereby exposed to all kinds of stresses and tensions.


I've long been under the impression that patch kit cement
is of the vulcanizing kind, but upon further research I'm
prepared to admit to error on my part.


If patch kit rubber cement truly is non-vulcanizing, it
nevertheless works for inner tube patches when it's properly
applied, the layers of cement are allowed to set ("cure")
for a few minutes before applying patch to hole, and the
patched tube is rested overnight before inflating.


I suspect the reason for letting the cement dry for a
few minutes before sticking the patch on, is to let it
become more viscous so that Surface Tension pulls (pushes?)
the patch more firmly into place against the tube. *I think
the "good" rubber cement for tube patching has a solvent
in it, like acetone or some kind of pentane or other volatile
solvent who's job is to *keep it storable & fluid enough
to spread it, and that's the solvent's only purpose. *Once
the cement is applied, the next step is to let that solvent
evaporate so the remaining cement can do it's job.


What is vulcanizing? *From

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

"Vulcanization or vulcanisation refers to a specific curing process
of rubber involving high heat and the addition of sulfur or other
equivalent
curatives. It is a chemical process in which polymer molecules are
linked
to other polymer molecules by atomic bridges composed of sulfur atoms
or carbon to carbon bonds. The end result is that the springy rubber
molecules become cross-linked to a greater or lesser extent. This
makes
the bulk material harder, much more durable and also more resistant
to
chemical attack. It also makes the surface of the material smoother
and
prevents it from sticking to metal or plastic chemical catalysts."

And so on. *It should be apparent that patch cement
does not "vulcanize." *It's a sales term.

I patch tubes with rubber cement out of a jar. *My
current jar is Elmer's. *I don't have problems with
patches coming off or failing. *I've even patched cuts
without an official patch, using rubber cement from
the jar and a piece of old inner tube. *You have to be
very scrupulous about removing the mold release
for this to work. *I did it as a challenge to see if
I could fix a cut without putting in a very large
stiff patch.

I let the cement dry pretty thoroughly before
applying patches. *I also rub them on with a
tire lever end or similar. *Contrary to your speculation
about humidity and pressure (the pressure
difference is small and couldn't be significant),
I do most of my patching in low humidity
since I live in a dry place.

IMO, most patch failures are due to improper
preparation or rushing.


Of which, ready prepared patches should help to aleviate, although
some think the solution is the solution and do no preperation.
  #27  
Old April 27th 09, 12:43 AM posted to rec.bicycles.misc,rec.bicycles.tech
Nick L Plate
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Posts: 1,114
Default Elmer's Rubber Cement is not the vulcanizing kind!

On 26 Apr, 05:49, wrote:
On Sat, 25 Apr 2009 21:37:09 -0700 (PDT), "



wrote:
On Apr 24, 8:58*pm, (Tom Keats) wrote:
* * * * Tom Sherman writes:


Where can I buy (in bulk) a large amount of the vulcanizing cement
from at the best price?


I was under the impression that vulcanizing requires heat and a curative
to produce cross-linking of the polymers, and "vulcanizing fluid" is a
marketing term.


As I understand it, so-called "vulcanizing" rubber cement
chemically integrates with the existing rubber to which
it is applied. *This effect should be desirable with
regard to tire repairs, since holes in tires are external
and thereby exposed to all kinds of stresses and tensions.


I've long been under the impression that patch kit cement
is of the vulcanizing kind, but upon further research I'm
prepared to admit to error on my part.


If patch kit rubber cement truly is non-vulcanizing, it
nevertheless works for inner tube patches when it's properly
applied, the layers of cement are allowed to set ("cure")
for a few minutes before applying patch to hole, and the
patched tube is rested overnight before inflating.


I suspect the reason for letting the cement dry for a
few minutes before sticking the patch on, is to let it
become more viscous so that Surface Tension pulls (pushes?)
the patch more firmly into place against the tube. *I think
the "good" rubber cement for tube patching has a solvent
in it, like acetone or some kind of pentane or other volatile
solvent who's job is to *keep it storable & fluid enough
to spread it, and that's the solvent's only purpose. *Once
the cement is applied, the next step is to let that solvent
evaporate so the remaining cement can do it's job.


What is vulcanizing? *From


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


"Vulcanization or vulcanisation refers to a specific curing process
of rubber involving high heat and the addition of sulfur or other
equivalent
curatives. It is a chemical process in which polymer molecules are
linked
to other polymer molecules by atomic bridges composed of sulfur atoms
or carbon to carbon bonds. The end result is that the springy rubber
molecules become cross-linked to a greater or lesser extent. This
makes
the bulk material harder, much more durable and also more resistant
to
chemical attack. It also makes the surface of the material smoother
and
prevents it from sticking to metal or plastic chemical catalysts."


And so on. *It should be apparent that patch cement
does not "vulcanize." *It's a sales term.


I patch tubes with rubber cement out of a jar. *My
current jar is Elmer's. *I don't have problems with
patches coming off or failing. *I've even patched cuts
without an official patch, using rubber cement from
the jar and a piece of old inner tube. *You have to be
very scrupulous about removing the mold release
for this to work. *I did it as a challenge to see if
I could fix a cut without putting in a very large
stiff patch.


I let the cement dry pretty thoroughly before
applying patches. *I also rub them on with a
tire lever end or similar. *Contrary to your speculation
about humidity and pressure (the pressure
difference is small and couldn't be significant),
I do most of my patching in low humidity
since I live in a dry place.


IMO, most patch failures are due to improper
preparation or rushing.


Ben


Dear Ben,

Google for "cold vulcanizing fluid"--it's a widely used term in the
industrial belt industry.

Cold vulcanizing fluid simply uses chemicals that produce the
cross-linking that's one of features of hot vulcanization.

In contrast, plain rubber cement works by interdigitation without the
chemical changes of cross-linking--rubber cement isn't cold
vulcanizing fluid.


No it's just rubber. Plain old rubber. A high shear strength contact
adhesive which may be suitable for booting tyre casings is a synthetic
formulation, I think I have just removed a tub's basetape which had
been manufactured using the synthetic to b0ond the tape to the rubber
on the casing. Definitely stronger than the usual contact bond.
  #28  
Old April 27th 09, 12:47 AM posted to rec.bicycles.misc,rec.bicycles.tech
Nick L Plate
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Posts: 1,114
Default Elmer's Rubber Cement is not the vulcanizing kind!

On 26 Apr, 15:15, Still Just Me
wrote:
On Sun, 26 Apr 2009 04:51:06 -0700 (PDT),
wrote:

On further investigation it seems that some bicycle tire tube patch
adhesives may indeed contain rubber vulcanization accelerators. For
example the MSDS(Material Data Safety Sheet) for REMA Tip Top
Vulcanizing Fluid CFC Free indicates that it contains 1.0 – 2.5 %Wt of
N-Ethylcyclohexylamine, an amine having a *number of commercial
applications including use in rubber formulations. The general
mechanism of tube patch adhesion remains, I believe, as indicated
above.


So, bottom line what are the recommended glues?

I don't use patch kits, I've always just used a piece of tube to
patch. Patch kits always seemed like a very expensive way to get a
very small tube of cement and some precut rubber in a small box.

What's a suggested glue for tube on tube patching?


What have you?
  #29  
Old April 27th 09, 01:10 AM posted to rec.bicycles.misc,rec.bicycles.tech
Tom Keats
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Posts: 3,193
Default Elmer's Rubber Cement is not the vulcanizing kind!

In article ,
Michael Press writes:
In article ,
(Tom Keats) wrote:

Now I'm wondering
how those long polymers find their ways into their holes
or ruts or whatever allows them to interdigitate -- do
they just fall in when a hole opens up beneath them,
or do they just randomly flow around until they drop
into a hole/rut/whatever? If they're electrically drawn
in, could that arguably be a chemical process?


Physically it is similar to interleaving the pages of
two books.


Interleaving the pages of two books requires thought
and intention and maybe a little cleverness, if the
job is to be done neatly, without collisions.

What forces are at work with this interdigitation/
interleaving? What downright ~makes~ polymers
first agree to interdigitate, and then move around
to align themselves accordingly? Or is this just
another one of those axiomatic things?

Adjacent books don't suddenly decide to interleave
their pages, neither does a jumbled pile of bricks
decide to form a chimney. So I'm having difficulty
with the concept of molecular chains somehow elegantly
and neatly (but non-chemically) organizing themselves
by dint of their proximity to each other.

We're being told one substance somehow molecularly
intimates and intermingles itself with another
similar substance, and yet the process is not
chemical.

BTW, as a preemptive afterthought: Jim Beam and the
horse he rode into town on can both enjoy precious
moments with their respective selves.

Or each other, if they're into that.



cheers,
Tom


--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca
  #30  
Old April 27th 09, 01:19 AM posted to rec.bicycles.misc,rec.bicycles.tech
Nick L Plate
external usenet poster
 
Posts: 1,114
Default Elmer's Rubber Cement is not the vulcanizing kind!

On 27 Apr, 01:10, (Tom Keats) wrote:

What forces are at work with this interdigitation/
interleaving? *What downright ~makes~ polymers
first agree to interdigitate, and then move around
to align themselves accordingly? *Or is this just
another one of those axiomatic things?


Lower the surface tension by heat or chemical.

Adjacent books don't suddenly decide to interleave
their pages, neither does a jumbled pile of bricks
decide to form a chimney. *So I'm having difficulty
with the concept of molecular chains somehow elegantly
and neatly (but non-chemically) organizing themselves
by dint of their proximity to each other.


make 'em wet and jiggle a little. The proximity and movement enables
the cross bonding. They'll come right in the end.

 




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