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#21
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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 |
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#22
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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. |
#23
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Elmer's Rubber Cement is not the vulcanizing kind!
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#25
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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
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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
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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
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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
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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
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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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