[lgalla]

Here is a comparison of some materials we are looking at.
Solid glass spheres:
Crush strength 30,000psi
Mohs 6
Density 2.5g/cc
Zeeospheres
Crush strength 60,000psi
Mohs 7
Density 2.1g/cc
Granite
compressive strength 19,000 to 29,000psi
Mohs 7
density 2.75g/cc
E/G
compressive strength 18,000psi
Density 2.3g/cc
Is crush strength the same as compressive strength?If so Zeeospheres look good.We are fooling around with different materials and additives.E/G from the manfactures is simply sand and aggregates for vibration damping.Changing the materials or upping the properties will not guarante vibra damp properties.Zeeospheres are looking good.Patent anyone?
Walter did some Zeo only in epoxy.Walter any news?
Larry

[walter]

I just finished reading on Silane, this gas autoignites at 21deg C.

That's room temperature!!

I could use a bonding agent.. Do they sell it online?
_

[ckelloug]

<h5> Silane vs. Polymers made from Silane</h5>
First off, let me clarify my remark about silane coupling agents. Silane proper is a gas which is chemically similar to natural gas except that that it contains silicon where natural gas contains carbon. It in and of itself is not overly useful to us. It's also definitely not something we want around the shop due to autoignition as brunog pointed out.

Silane based coupling agents are made from silane but it is a different chemical with a lot of additions that is in liquid form. The MSDS for a generic epoxy coupling agent is hazardous but it looks like the major hazard from the Dow datasheet attached is methyl alcohol (lacquer thinner/ steam engine fuel). Dow also lists the ability to get 60ml samples. The stuff is mixed up with water and the mix is applied the the inorganic material. Maybe it's why I'm crazy and spending my sabbatical engineering machine parts, but I played with enough methyl alcohol as a kid that I'm not ready to concede major danger from that component.

Ironically, for many of these materials, they will not sell you any but will instead give you more than you could ever use. . . I have two one pound jars of carbon black that arrived today as a gift from Cabot.

<h5>Conclusion 1: Silane coupling agent danger probably not too high</h5>
While we may have trouble obtaining silane based coupling agents or decide they are too hazardous ultimately for a general purpose recipe, my general opinion is that they aren't too bad in small quantities if treated with slightly more care than you would oil based paint. Gaseous silane on the other hand sounds about as pleasant as Arsine and I don't don't think I'd want to be near the 10 foot pole that touched the 10 foot pole that touched either of them.

<h5>Mechanisms of Composite Reinforcement and spheres as reinforcement</h5>
Spheres are a fine reinforcing agent. They provide an isotropic material which means that it is the same strength in all directions. The graph I posted some posts back about the rule of mixtures applies to composites reinforced with materials like glass spheres or sand.

There are several types of materials for reinforcing composites and the mechanisms and governing principles are different between them. Composities made from a matrix filled with spheres or objects that are approximated by spheres (like concrete and E/G) are governed by the rules large particle composites.

Composites reinforced with fibers are governed by the rules of fiber composites which are and are generally higher strength but anisotropic (different strengths in different directions).

Finally composites reinforced with nanoparticles are dispersion hardened composites and I've not found any governing equations for them other than that more is better up to 14% by volume though 10 percent by volume is the point where additional nanoparticles seem to have a small effect.

<h5>Conclusion: Spheres are a fine reinforcement and their isotropic nature is not a hinderance for making large particle composites</h5>

<h5>Fill percentage of a box of spheres</h5>

The fill rate of particles in a box (considered spheres for engineering purposes) varies between 5% and 75% and probably depends on how much they are shaken etc. Walter's data seem to indicate that the fill rate goes up as particles sizes go down. It is a physical and mathematical impossibility to get the fill rate above 75% when you have only one size of particle. In general, the packing rate of various mixtures of different sized spheres appears to be not well defined in the literature although some of the references in the stuff posted by brunog indicate that theoretical results do exist for groups of only 3 different sizes. Even zeospheres have size variation so anything we come up with is only a guideline.

Fulton's equation from the Sahmenko PHD thesis brunog posted seems like it is the most oldschool method for cases where sieved aggregates are being used.

<h5>Conclusion: More data is needed to determine what the proper ratios are for this though I personally believe my suggestion from my last post is not a horrible starting point.</h5>

<h5>Zeospheres</h5>

The crush strength is most likely the ultimate compressive strength which for the smaller spheres is much better than granite and quartz. Due to their spherical nature and extreme quality control, I believe zeospheres are like to produce the most repeatable possible E/G E/Q E/Z. In that sense, I think Zeospheres might also prove to be the E/Z'est to use. They're not as cheap as other materials but they're not unreasonably expensive. Since they are spheres, they will also tend to behave more closely to theoretical performance equations.

I'd probably try a mixture of G3150, G850 and G600 in the 1: 0.414 : 0.086 even though the crush strength of the 3150 is low. By this ratio, I mean that the second is .414 times the first and the third is .086 times the first. The material in the zeospheres has similar density so I'd imagine these ratios by weight are not too bad. Like I said before, this is a ratio that won't interfere with the body centered cubic structure which is optimal. Nothing says we will get BCC structure but making the second aggregate bigger guarantees we won't. This is still guessing because zeospheres aren't just one size. . .

The low strength of the G3150 is most likely due to the larger spheres being too large to avoid the critical flaw size and I think they should have similar modulus as the others even if they cannot sustain the same load: loads we probably won't come close to.


SO, for zeospheres, I'd try the recipe G3150, G850 and G600 in the 1: 0.414 : 0.086 with 3% by weight TS-0530, 3% Silane-based coupling agent treated carbon black, and the right amount of nanopox to get 10% of the regular epoxy volume as nanospheres. I'd combine this with 1% BYK-A525 deairing agent for epoxy granite some dow z6040 coupling agent to pretreat the zeospheres and voila. I feel like the healer in the movie the Princess Bride. . .

I'd probably mix the resin and all the additives together for quite a while then add the hardener and continue mixing. I've been wondering if we can't hack together something like a mixing extruder by twisting a flat long thing piece of metal a few times and then sticking it in a piece of pvc pipe and adding a shaft to turn the piece such that it forces the epoxy mixture to recirculate up and down in the pipe.

I gotta get back to writing the software I need to be writing so I hope this is moderately helpful.

[walter]

I've got 2 samples with 60% zeeospheres and 40% superfine quartz.

One has 4 layers of fiberglass.

Testing apparatus should be ready in a few days.

[ckelloug]

What kind of testing apparatus are you looking at?

[walter]

What others suggested: improvised screw press jig with a torque wrench.

I might also visit a local granite supplier to see if I can borrow a sample.

[Zumba]

Walter, any details on the screw press jig?

The problem with a torque wrench is that you're measuring the total force required including friction. Do you think belleville disc springs would be more accurate?

[brunog]

Guys,
I found all my aggregates:

700 micron washed and dry play sand

2mm granite pool sand

3-5mm washed quartz found in a loca quarry 4 miles away from home

I think of using a 1: 0.53: .69 ratio this is based on Fuller's parabola as a first test.


Cameron,
Mixpack make great mixers:

http://www.mixpacequipment.com/

Best regards

Bruno

[ckelloug]

Bruno,

Please make sure to post your results! This sounds like it will be rather interesting and ought to work pretty darn well from all the theory I've read. It'll be a month before I can start to do any testing

[brunog]

It'll be a month before I can start to do any testing

Cameron,
I still need to find a local epoxy distributor in the Montreal area.I am starting to run out of spare time, however, If everything goes well, I should be casting a first sample in a couple of weeks.

I will for sure post my results

Best regards

Bruno

[ckelloug]

Zumba,

Can you elaborate about what you mean? I have not seen a belleville spring so I am visualizing that your idea is to measure linear deflection in the spring instead of torque.

--Cameron

[lgalla]

Bruno US Composites is still a good choice,UPS will charge an additional 50 bucks for customs brokerage and GST.

[Zumba]

Cameron,

A belleville disc bring is a conical washer that requires a set amount of force to compress it flat. Basically in a jig, you'd use it as a washer. If your belleville has a "flat" rating of 400 lbs, that means when you torque down the nut such that the belleville has compressed about 90%, it will effectively be applying 400 lbs of linear force. Friction in the threads won't affect it.

You want to leave about 10% from totally flat so that you don't overtorque the nut by mistake.

[walter]

Thanks Zumba, that is pretty cool.
I see if I can find it in my local store.

[lgalla]

Bruno a Canadian epoxy formulator is [url]www.crosslinktech.com
Larry

[lgalla]

Turbulant mixers.
Turbulant mixers are a great invention,but of no use with highly vicious materials like Sid Vicious or my vicious dog.They have a high viscosity and would require huge psi to be or not to be effective.The vicious os ity of 10% epoxy is too dry a mix to effectively benifit from turbulant mixing.:cheers:
If you do not understand the post it is not important to E/G as it is a dead end.Peroid

[lgalla]

Sorry Bruno, I forgot,L.V.Lomas has Epotuf.Don't know if they sell small quantities.
Larry

[brunog]

Thanks for the info Larry.

Best regards

Bruno

[brunog]

Turbulant mixers.
Turbulant mixers are a great invention,but of no use with highly vicious materials like Sid Vicious or my vicious dog.They have a high viscosity and would require huge psi to be or not to be effective.The vicious os ity of 10% epoxy is too dry a mix to effectively benifit from turbulant mixing.:cheers:
If you do not understand the post it is not important to E/G as it is a dead end.Peroid

Larry,
Couldn't turbulent mixers be used to mix the epoxy only?

[BobWarfield]

Thanks Zumba, that is pretty cool.
I see if I can find it in my local store.

Try McMaster-Carr. They're not very expensive and available in a variety of sizes.

Best,

BW