I want to basically have a mixture of 95% granulated glass and 5% adhesive. The adhesive needs to bond the glass together and must also bond the glass to a wood substrate. An epoxy that bonds to wood and this epoxy would work too (like a glass/epoxy mix, epoxy, wood sandwich) I have little chemistry experience but if you could point me in the right direction I would appreciate it.
gluing silicon dioxide
- Thread starter TheoPetro
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PottedMeat
Lifer
- Apr 17, 2002
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Is this some sort of sanding block?
Sandpaper
Getting down to the nitty-gritty of the ubiquitous abrasive
http://pubs.acs.org/cen/whatstuff/85/8530sci2.html
Sounds like you can just see if it works.
Its not going to be a sanding block but I want to be able to spread the glass/adhesive mixture like frosting but have it set up hard. The problem is that there must be less than 5% adhesive in the mixture for it to work properly.
herm0016
Diamond Member
- Feb 26, 2005
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what are you building? this may help us out.
if it does not have to be uv resistant i recommend west system epoxy www.westsystem.com. i have used this with great success for many projects including adding different solid fillers to it to make it thick and light weight. it will stick to anything.
if it does not have to be uv resistant i recommend west system epoxy www.westsystem.com. i have used this with great success for many projects including adding different solid fillers to it to make it thick and light weight. it will stick to anything.
I cant go into details of what im building because its proprietary at the moment. It does not need to be UV resistant. I was actually thinking of some type of emulsifier that we could spread it on the wood and hit it with a UV light for 5 min and have it set up that way. This mixture will be sitting in a dark place that should be dry for the most part but if it does get exposed to moisture it has to hold up fairly well. AKA it cant be a gooy mess on the floor after it gets some condensation on it.
Sorry but I cant go into details of what it actually is yet. Once the product goes public I can talk about it freely.
Sorry but I cant go into details of what it actually is yet. Once the product goes public I can talk about it freely.
PottedMeat
Lifer
- Apr 17, 2002
- 12,363
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Can you tell us the grain size - I was going to suggest one of those 3M spray adhesive things and sift the grains on the surface, but I don't know if they set up hard and you said you want a frosting type goo.
grain size at this stage is roughly 2mm in diameter. I think its possible to go as small as .2-.5mm and still get the effect were looking for.
I'm not sure what to recommend for an adhesive (still learning about that area myself), but I do have a comment on your need for <5%. If you consider the problem of maximum packing density of non-spherical particles in a continuous medium (epoxy in your case), you typically find numbers around 70%. This number varies quite a bit and affected by such things as particle size distribution, particle shape, and method of preparing the suspension, but I think, even tweaking these things, you would find it quite difficult to pack in more than 75-80% by volume sand in epoxy and still have it be a liquid like frosting.
While non-spherical particles actually pack best, lets illustrate this with spherical packing. Imagine a 2-dimensional array of spheres at close packing. Each sphere has 6 nearest neighbors, leading to a hexagonally packed array. In 3-dimensions, you take multiple of these same 2-D layers and offset them so that the spheres of one layer sit in the gaps of the adjacent layer. This gives you a maximum packed volume fraction of 74%. But note that this is essentially a crystalline solid and will not flow. Now imagine that you add another set of smaller spheres to the mix. These are small enough to flow in the gaps left by the first set. These will be able to increase the volume fraction more, although they can not pack as efficiently as the first set (unless they are much smaller) due to the irregular volume they have to fill. Of course, if you put on your fractal sunglasses, you see that you can continue this process over a variety of sizes to further increase the volume fraction. Of course, making it flow in a suspension wil lget increasingly harder.
So essentially, I think the chances of you getting a flowing suspension of glass particles at 95% by volume is pretty much nil. Of course, if you really only need <5% binder and not necessarily 95% glass, there may be other options. I imagine there are methods that would bind the spheres together without fully filling in the gaps between them leading to a glass/binder/air mixture something like 70/5/25. If that would work, let us know and maybe we can think about how to do that, since it definitely getting more complicated than your original plan.
Good luck with your product.
-Tim
While non-spherical particles actually pack best, lets illustrate this with spherical packing. Imagine a 2-dimensional array of spheres at close packing. Each sphere has 6 nearest neighbors, leading to a hexagonally packed array. In 3-dimensions, you take multiple of these same 2-D layers and offset them so that the spheres of one layer sit in the gaps of the adjacent layer. This gives you a maximum packed volume fraction of 74%. But note that this is essentially a crystalline solid and will not flow. Now imagine that you add another set of smaller spheres to the mix. These are small enough to flow in the gaps left by the first set. These will be able to increase the volume fraction more, although they can not pack as efficiently as the first set (unless they are much smaller) due to the irregular volume they have to fill. Of course, if you put on your fractal sunglasses, you see that you can continue this process over a variety of sizes to further increase the volume fraction. Of course, making it flow in a suspension wil lget increasingly harder.
So essentially, I think the chances of you getting a flowing suspension of glass particles at 95% by volume is pretty much nil. Of course, if you really only need <5% binder and not necessarily 95% glass, there may be other options. I imagine there are methods that would bind the spheres together without fully filling in the gaps between them leading to a glass/binder/air mixture something like 70/5/25. If that would work, let us know and maybe we can think about how to do that, since it definitely getting more complicated than your original plan.
Good luck with your product.
-Tim
I think Tim is right. Getting down to less than 5% will be difficult. What's wrong with the epoxy they use for fiberglass?
PolymerTim is right about packing densities, etc, and mentions other methods that end up including air. I work in the coated paper business and that's what we get in a coating.
In our business, the coating contains granular pigments, adhesives, minor additives, and water as a dispersing medium. As applied in a wet slurry that looks exactly like white paint, it is about 67% to 70% dry solids and the rest is water. Once it is spread out evenly it is dried quickly to evaporate the water. When enough water is removed (typically less than 80% dry solids), the water no longer fills all the spaces between the solid particles, and we have the "point of immobolization"; from here on up to completely dry, the solid particles cannot move past each other. Drying continues until the final target, typically about 95% dry solids. As the water evaporates it leaves behind very small empty spaces filled with air. The final coating layer is about 86% pigment, 9% adhesive and 5% water in most of the papers I have made, but some grades are made with less adhesive.
In your case I suspect you do not want to be using a water-based adhesive system. But if you use an adhesive that is soluble in a volatile organic solvent you can make a slurry of pigment (glass particles), adhesive and solvent which is fluid enough to handle and apply, then evaporate the solvent and get what you want. BUT it will have small air voids in the structure.
There are a lot of important subtleties in this business around solids levels, low- and high-shear viscosity of the fluid coating, penetration of the dispersing medium into the substrate, and the selective movement with the liquid medium of pigment fines and adhesive particles, but that's well beyond this discussion.
In our business, the coating contains granular pigments, adhesives, minor additives, and water as a dispersing medium. As applied in a wet slurry that looks exactly like white paint, it is about 67% to 70% dry solids and the rest is water. Once it is spread out evenly it is dried quickly to evaporate the water. When enough water is removed (typically less than 80% dry solids), the water no longer fills all the spaces between the solid particles, and we have the "point of immobolization"; from here on up to completely dry, the solid particles cannot move past each other. Drying continues until the final target, typically about 95% dry solids. As the water evaporates it leaves behind very small empty spaces filled with air. The final coating layer is about 86% pigment, 9% adhesive and 5% water in most of the papers I have made, but some grades are made with less adhesive.
In your case I suspect you do not want to be using a water-based adhesive system. But if you use an adhesive that is soluble in a volatile organic solvent you can make a slurry of pigment (glass particles), adhesive and solvent which is fluid enough to handle and apply, then evaporate the solvent and get what you want. BUT it will have small air voids in the structure.
There are a lot of important subtleties in this business around solids levels, low- and high-shear viscosity of the fluid coating, penetration of the dispersing medium into the substrate, and the selective movement with the liquid medium of pigment fines and adhesive particles, but that's well beyond this discussion.
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