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Elmer's Rubber Cement is not the vulcanizing kind!
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 |
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#13
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Elmer's Rubber Cement is not the vulcanizing kind!
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. Cheers, Carl Fogel |
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Elmer's Rubber Cement is not the vulcanizing kind!
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Elmer's Rubber Cement is not the vulcanizing kind!
On Apr 24, 10:58*pm, (Tom Keats) wrote:
In article , * * * * Tom Sherman writes: Ablang ? wrote: I bought a 4oz jar (UPC 0 269050 8) of this stuff from Home Depot last year for about $2.50. *Pretty cheap stuff. I finally got a chance to use these on my inner tubes for my 27" x 1-1/4" tires (100 psi) and found out that they don't really stick permanently. *The next day I discover that some part of the patch has breached. In trying to figure out what I did wrong (I have successfully patched other tires before using the glue from patch kits), I figure it's that I'm either using too thick of a layer of Elmer's or that this rubber cement really isn't the vulcanizing kind. What do you guys think? 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. I might be wrong about that, too -- I'm just guessing. Maybe Jobst will set us all straight. Maybe it's better to patch inner tubes during a rainy day, when the air pressure is higher? *Surface tension, 'n all that. cheers, * * * * Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca I believe with respect to bicycle tire tube patch adhesive “Cold vulcanizing” is a misnomer in so far as it implies that a chemical reaction is facilitated. Here the “accelerators” – common commercial organic solvents that under normal conditions do not chemically react with rubber – function only as a solvent system for both the rubber dissolved in the so called “cold vulcanizing fluid” and a partial solvent system for the tube and the patch. This partial solvation allows for the integration and fusion of the rubber particles of the tube, adhesive, and the patch into a more or less homogeneous whole. If these solvents are not allowed to volatilize sufficiently, say for a period of twenty four hours, the tire rubber and patch rubber may remain sufficiently solvated to allow for their easy separation. The dissolved rubber of the tire patch adhesive – the so called “cold vulcanizing fluid” – retains and thus slows the volatilization of its solvents allowing for the partial solvation of the patch and tube rubber by these solvents. There are a myriad of other rubber based adhesives for different and specialized applications; many certainly do undergo chemical reactions, and some of these may additionally be termed “cold vulcanizing”. ___ Spike |
#16
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Elmer's Rubber Cement is not the vulcanizing kind!
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. cheers, Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca |
#17
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Elmer's Rubber Cement is not the vulcanizing kind!
On Apr 26, 3:44*am, wrote:
On Apr 24, 10:58*pm, (Tom Keats) wrote: In article , * * * * Tom Sherman writes: Ablang ? wrote: I bought a 4oz jar (UPC 0 269050 8) of this stuff from Home Depot last year for about $2.50. *Pretty cheap stuff. I finally got a chance to use these on my inner tubes for my 27" x 1-1/4" tires (100 psi) and found out that they don't really stick permanently. *The next day I discover that some part of the patch has breached. In trying to figure out what I did wrong (I have successfully patched other tires before using the glue from patch kits), I figure it's that I'm either using too thick of a layer of Elmer's or that this rubber cement really isn't the vulcanizing kind. What do you guys think? 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. I might be wrong about that, too -- I'm just guessing. Maybe Jobst will set us all straight. Maybe it's better to patch inner tubes during a rainy day, when the air pressure is higher? *Surface tension, 'n all that. cheers, * * * * Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca I believe with respect to bicycle tire tube patch adhesive “Cold vulcanizing” is a misnomer in so far as it implies that a chemical reaction is facilitated. *Here the “accelerators” – common commercial organic solvents that under normal conditions do not chemically react with rubber – *function only as a solvent system for both the rubber dissolved in the so called “cold vulcanizing fluid” and a partial solvent system for the tube and the patch. This partial solvation allows for the integration and fusion of the rubber particles of the tube, adhesive, and the patch into a more or less homogeneous whole. If these solvents are not allowed to volatilize sufficiently, say for a period of twenty four hours, the tire rubber and patch rubber may remain sufficiently solvated *to allow for their easy separation. The dissolved rubber of the tire *patch adhesive – the so called “cold vulcanizing fluid” – retains and thus slows the volatilization of its solvents allowing for the partial solvation of the patch and tube rubber by these solvents. There are a myriad of other rubber based adhesives for different and specialized applications; many certainly do undergo chemical reactions, and some of these may additionally be termed “cold vulcanizing”. ___ Spike 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. ___ Spike |
#18
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Elmer's Rubber Cement is not the vulcanizing kind!
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. oh, for ****'s sake. The patch & tube aren't just holding hands and interdigitating -- they're really cleaving unto each other and becoming one flesh, like Adam & Eve. get thine dumb religious ass off to school will ya? learn math. learn chemistry. then quit posting this kind of crap. 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. cheers, Tom -- Nothing is safe from me. nothing is safe /for/ the incurably incurious. I'm really at: tkeats curlicue vcn dot bc dot ca |
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Elmer's Rubber Cement is not the vulcanizing kind!
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? are you for real? how can you read a post that just tells you mechanism and application, yet still utterly fail to comprehend what it means? [rhetorical] |
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Elmer's Rubber Cement is not the vulcanizing kind!
wrote:
On Sat, 25 Apr 2009 10:14:44 -0700, (Tom Keats) wrote: In article , writes: On Fri, 24 Apr 2009 20:58:24 -0700, l (Tom Keats) wrote: In article , Tom Sherman writes: Ablang ? wrote: I bought a 4oz jar (UPC 0 269050 8) of this stuff from Home Depot last year for about $2.50. Pretty cheap stuff. I finally got a chance to use these on my inner tubes for my 27" x 1-1/4" tires (100 psi) and found out that they don't really stick permanently. The next day I discover that some part of the patch has breached. In trying to figure out what I did wrong (I have successfully patched other tires before using the glue from patch kits), I figure it's that I'm either using too thick of a layer of Elmer's or that this rubber cement really isn't the vulcanizing kind. What do you guys think? 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. I might be wrong about that, too -- I'm just guessing. Maybe Jobst will set us all straight. Maybe it's better to patch inner tubes during a rainy day, when the air pressure is higher? Surface tension, 'n all that. cheers, Tom Dear Tom, "Rubber cement works by a mechanism of cohesion [also called autohesion, or 'self-sticking-to-self] but this is true both for the paper gluing example and the rubber gluing example, provided there is cement on both pieces of paper." "Cohesion occurs when the long polymer chains of the adhesive material are able to penetrate and mix with the polymer chains of the adherend [the substrate]. This process is also called 'interdigitation' in reference to the simile of fingers of opposite hands interlaced, as if in prayer. It is much harder to separate hands with interlaced fingers than when the hands simply lay one on the other." "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. 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 Thanks, Carl. I'm now edified. I have for a long time noted how patches seem to be either pulled or pushed onto the surfaces to which they're adhered, and I've casually wondered about whatever processes might be at work, but I've never actually gotten around to verbially articulating my puzzlement. 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? I am nevertheless still mystified by how a properly applied patch seems to be either pushed or pulled into place, as if an invisible thumb had been pressing on it all night long. The patch doesn't just lie there like a fillet of sole or a postage stamp -- some force has snuggled it intimately right up to the inner tube, as if patch & tube are spooning. If it's those long polymer thingies, they must act like an octopus's tentacles drawing its prey to its beak. But to the best of my limited knlowledge, molecules don't possess volition. I guess the clue lies in whatever keeps an improperly applied patch from working. But I have another poser for you, if you're inclined to spend even more time in response: what does so-called "vulcanizing" rubber cement do, that non-vulcanizing rubber cement doesn't? During my more austere days, I found that vulcanizing rubber cement works better than non-vulcanizing rubber cement (or contact cement for that matter) for minor, external ~tire~ repairs. A swatch of jeans denim slathered with contact cement makes a fairly usable internal boot, but you can feel the lump with each wheel rotation. cheers, Tom Dear Tom, Rubber cement works by interdigitation, with no chemical changes. It doesn't vulcanize the rubber pieces, meaning that no cross-links are formed and no chemical changes occur. Cold vulcanizing fluid contains chemicals (the "accelerators" below) that do produce cross-links between the rubber molecules, just as hot vulcanizing (heat plus sulphur) changes the chemical structure of rubber. The wait-until-tacky prescription for cold vulcanizing fluid has a surprisingly simple explanation: "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? |
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